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AN ENQUIRY CONCERNING HUMAN UNDERSTANDING.

BY DAVID HUME

Extracted from:
Enquiries Concerning the Human Understanding, and Concerning the
Principles of Morals, By David Hume.

Reprinted from The Posthumous Edition of 1777, and Edited with
Introduction, Comparative Tables of Contents, and Analytical Index
by L.A. Selby-Bigge, M.A., Late Fellow of University College, Oxford.

Second Edition, 1902

CONTENTS

I. Of the different Species of Philosophy
II. Of the Origin of Ideas
III. Of the Association of Ideas
IV. Sceptical Doubts concerning the Operations of the Understanding
V. Sceptical Solution of these Doubts
VI. Of Probability
VII. Of the Idea of necessary Connexion
VIII. Of Liberty and Necessity
IX. Of the Reason of Animals
X. Of Miracles
XI. Of a particular Providence and of a future State
XII. Of the academical or sceptical Philosophy

INDEX

SECTION I.

OF THE DIFFERENT SPECIES OF PHILOSOPHY.

1. Moral philosophy, or the science of human nature, may be treated
after two different manners; each of which has its peculiar merit, and
may contribute to the entertainment, instruction, and reformation of
mankind. The one considers man chiefly as born for action; and as
influenced in his measures by taste and sentiment; pursuing one object,
and avoiding another, according to the value which these objects seem to
possess, and according to the light in which they present themselves. As
virtue, of all objects, is allowed to be the most valuable, this species
of philosophers paint her in the most amiable colours; borrowing all
helps from poetry and eloquence, and treating their subject in an easy
and obvious manner, and such as is best fitted to please the
imagination, and engage the affections. They select the most striking
observations and instances from common life; place opposite characters
in a proper contrast; and alluring us into the paths of virtue by the
views of glory and happiness, direct our steps in these paths by the
soundest precepts and most illustrious examples. They make us _feel_ the
difference between vice and virtue; they excite and regulate our
sentiments; and so they can but bend our hearts to the love of probity
and true honour, they think, that they have fully attained the end of
all their labours.

2. The other species of philosophers consider man in the light of a
reasonable rather than an active being, and endeavour to form his
understanding more than cultivate his manners. They regard human nature
as a subject of speculation; and with a narrow scrutiny examine it, in
order to find those principles, which regulate our understanding, excite
our sentiments, and make us approve or blame any particular object,
action, or behaviour. They think it a reproach to all literature, that
philosophy should not yet have fixed, beyond controversy, the foundation
of morals, reasoning, and criticism; and should for ever talk of truth
and falsehood, vice and virtue, beauty and deformity, without being able
to determine the source of these distinctions. While they attempt this
arduous task, they are deterred by no difficulties; but proceeding from
particular instances to general principles, they still push on their
enquiries to principles more general, and rest not satisfied till they
arrive at those original principles, by which, in every science, all
human curiosity must be bounded. Though their speculations seem
abstract, and even unintelligible to common readers, they aim at the
approbation of the learned and the wise; and think themselves
sufficiently compensated for the labour of their whole lives, if they
can discover some hidden truths, which may contribute to the instruction
of posterity.

3. It is certain that the easy and obvious philosophy will always, with
the generality of mankind, have the preference above the accurate and
abstruse; and by many will be recommended, not only as more agreeable,
but more useful than the other. It enters more into common life; moulds
the heart and affections; and, by touching those principles which
actuate men, reforms their conduct, and brings them nearer to that model
of perfection which it describes. On the contrary, the abstruse
philosophy, being founded on a turn of mind, which cannot enter into
business and action, vanishes when the philosopher leaves the shade, and
comes into open day; nor can its principles easily retain any influence
over our conduct and behaviour. The feelings of our heart, the agitation
of our passions, the vehemence of our affections, dissipate all its
conclusions, and reduce the profound philosopher to a mere plebeian.

4. This also must be confessed, that the most durable, as well as
justest fame, has been acquired by the easy philosophy, and that
abstract reasoners seem hitherto to have enjoyed only a momentary
reputation, from the caprice or ignorance of their own age, but have not
been able to support their renown with more equitable posterity. It is
easy for a profound philosopher to commit a mistake in his subtile
reasonings; and one mistake is the necessary parent of another, while he
pushes on his consequences, and is not deterred from embracing any
conclusion, by its unusual appearance, or its contradiction to popular
opinion. But a philosopher, who purposes only to represent the common
sense of mankind in more beautiful and more engaging colours, if by
accident he falls into error, goes no farther; but renewing his appeal
to common sense, and the natural sentiments of the mind, returns into
the right path, and secures himself from any dangerous illusions. The
fame of Cicero flourishes at present; but that of Aristotle is utterly
decayed. La Bruyere passes the seas, and still maintains his reputation:
But the glory of Malebranche is confined to his own nation, and to his
own age. And Addison, perhaps, will be read with pleasure, when Locke
shall be entirely forgotten.

The mere philosopher is a character, which is commonly but little
acceptable in the world, as being supposed to contribute nothing either
to the advantage or pleasure of society; while he lives remote from
communication with mankind, and is wrapped up in principles and notions
equally remote from their comprehension. On the other hand, the mere
ignorant is still more despised; nor is any thing deemed a surer sign of
an illiberal genius in an age and nation where the sciences flourish,
than to be entirely destitute of all relish for those noble
entertainments. The most perfect character is supposed to lie between
those extremes; retaining an equal ability and taste for books, company,
and business; preserving in conversation that discernment and delicacy
which arise from polite letters; and in business, that probity and
accuracy which are the natural result of a just philosophy. In order to
diffuse and cultivate so accomplished a character, nothing can be more
useful than compositions of the easy style and manner, which draw not
too much from life, require no deep application or retreat to be
comprehended, and send back the student among mankind full of noble
sentiments and wise precepts, applicable to every exigence of human
life. By means of such compositions, virtue becomes amiable, science
agreeable, company instructive, and retirement entertaining.

Man is a reasonable being; and as such, receives from science his proper
food and nourishment: But so narrow are the bounds of human
understanding, that little satisfaction can be hoped for in this
particular, either from the extent of security or his acquisitions. Man
is a sociable, no less than a reasonable being: But neither can he
always enjoy company agreeable and amusing, or preserve the proper
relish for them. Man is also an active being; and from that disposition,
as well as from the various necessities of human life, must submit to
business and occupation: But the mind requires some relaxation, and
cannot always support its bent to care and industry. It seems, then,
that nature has pointed out a mixed kind of life as most suitable to the
human race, and secretly admonished them to allow none of these biasses
to _draw_ too much, so as to incapacitate them for other occupations and
entertainments. Indulge your passion for science, says she, but let your
science be human, and such as may have a direct reference to action and
society. Abstruse thought and profound researches I prohibit, and will
severely punish, by the pensive melancholy which they introduce, by the
endless uncertainty in which they involve you, and by the cold reception
which your pretended discoveries shall meet with, when communicated. Be
a philosopher; but, amidst all your philosophy, be still a man.

5. Were the generality of mankind contented to prefer the easy
philosophy to the abstract and profound, without throwing any blame or
contempt on the latter, it might not be improper, perhaps, to comply
with this general opinion, and allow every man to enjoy, without
opposition, his own taste and sentiment. But as the matter is often
carried farther, even to the absolute rejecting of all profound
reasonings, or what is commonly called _metaphysics_, we shall now
proceed to consider what can reasonably be pleaded in their behalf.

We may begin with observing, that one considerable advantage, which
results from the accurate and abstract philosophy, is, its subserviency
to the easy and humane; which, without the former, can never attain a
sufficient degree of exactness in its sentiments, precepts, or
reasonings. All polite letters are nothing but pictures of human life in
various attitudes and situations; and inspire us with different
sentiments, of praise or blame, admiration or ridicule, according to the
qualities of the object, which they set before us. An artist must be
better qualified to succeed in this undertaking, who, besides a delicate
taste and a quick apprehension, possesses an accurate knowledge of the
internal fabric, the operations of the understanding, the workings of
the passions, and the various species of sentiment which discriminate
vice and virtue. How painful soever this inward search or enquiry may
appear, it becomes, in some measure, requisite to those, who would
describe with success the obvious and outward appearances of life and
manners. The anatomist presents to the eye the most hideous and
disagreeable objects; but his science is useful to the painter in
delineating even a Venus or an Helen. While the latter employs all the
richest colours of his art, and gives his figures the most graceful and
engaging airs; he must still carry his attention to the inward structure
of the human body, the position of the muscles, the fabric of the bones,
and the use and figure of every part or organ. Accuracy is, in every
case, advantageous to beauty, and just reasoning to delicate sentiment.
In vain would we exalt the one by depreciating the other.

Besides, we may observe, in every art or profession, even those which
most concern life or action, that a spirit of accuracy, however
acquired, carries all of them nearer their perfection, and renders them
more subservient to the interests of society. And though a philosopher
may live remote from business, the genius of philosophy, if carefully
cultivated by several, must gradually diffuse itself throughout the
whole society, and bestow a similar correctness on every art and
calling. The politician will acquire greater foresight and subtility, in
the subdividing and balancing of power; the lawyer more method and finer
principles in his reasonings; and the general more regularity in his
discipline, and more caution in his plans and operations. The stability
of modern governments above the ancient, and the accuracy of modern
philosophy, have improved, and probably will still improve, by similar
gradations.

6. Were there no advantage to be reaped from these studies, beyond the
gratification of an innocent curiosity, yet ought not even this to be
despised; as being one accession to those few safe and harmless
pleasures, which are bestowed on human race. The sweetest and most
inoffensive path of life leads through the avenues of science and
learning; and whoever can either remove any obstructions in this way, or
open up any new prospect, ought so far to be esteemed a benefactor to
mankind. And though these researches may appear painful and fatiguing,
it is with some minds as with some bodies, which being endowed with
vigorous and florid health, require severe exercise, and reap a pleasure
from what, to the generality of mankind, may seem burdensome and
laborious. Obscurity, indeed, is painful to the mind as well as to the
eye; but to bring light from obscurity, by whatever labour, must needs
be delightful and rejoicing.

But this obscurity in the profound and abstract philosophy, is objected
to, not only as painful and fatiguing, but as the inevitable source of
uncertainty and error. Here indeed lies the justest and most plausible
objection against a considerable part of metaphysics, that they are not
properly a science; but arise either from the fruitless efforts of human
vanity, which would penetrate into subjects utterly inaccessible to the
understanding, or from the craft of popular superstitions, which, being
unable to defend themselves on fair ground, raise these intangling
brambles to cover and protect their weakness. Chaced from the open
country, these robbers fly into the forest, and lie in wait to break in
upon every unguarded avenue of the mind, and overwhelm it with religious
fears and prejudices. The stoutest antagonist, if he remit his watch a
moment, is oppressed. And many, through cowardice and folly, open the
gates to the enemies, and willingly receive them with reverence and
submission, as their legal sovereigns.

7. But is this a sufficient reason, why philosophers should desist from
such researches, and leave superstition still in possession of her
retreat? Is it not proper to draw an opposite conclusion, and perceive
the necessity of carrying the war into the most secret recesses of the
enemy? In vain do we hope, that men, from frequent disappointment, will
at last abandon such airy sciences, and discover the proper province of
human reason. For, besides, that many persons find too sensible an
interest in perpetually recalling such topics; besides this, I say, the
motive of blind despair can never reasonably have place in the sciences;
since, however unsuccessful former attempts may have proved, there is
still room to hope, that the industry, good fortune, or improved
sagacity of succeeding generations may reach discoveries unknown to
former ages. Each adventurous genius will still leap at the arduous
prize, and find himself stimulated, rather that discouraged, by the
failures of his predecessors; while he hopes that the glory of achieving
so hard an adventure is reserved for him alone. The only method of
freeing learning, at once, from these abstruse questions, is to enquire
seriously into the nature of human understanding, and show, from an
exact analysis of its powers and capacity, that it is by no means fitted
for such remote and abstruse subjects. We must submit to this fatigue,
in order to live at ease ever after: And must cultivate true metaphysics
with some care, in order to destroy the false and adulterate. Indolence,
which, to some persons, affords a safeguard against this deceitful
philosophy, is, with others, overbalanced by curiosity; and despair,
which, at some moments, prevails, may give place afterwards to sanguine
hopes and expectations. Accurate and just reasoning is the only catholic
remedy, fitted for all persons and all dispositions; and is alone able
to subvert that abstruse philosophy and metaphysical jargon, which,
being mixed up with popular superstition, renders it in a manner
impenetrable to careless reasoners, and gives it the air of science
and wisdom.

8. Besides this advantage of rejecting, after deliberate enquiry, the
most uncertain and disagreeable part of learning, there are many
positive advantages, which result from an accurate scrutiny into the
powers and faculties of human nature. It is remarkable concerning the
operations of the mind, that, though most intimately present to us, yet,
whenever they become the object of reflexion, they seem involved in
obscurity; nor can the eye readily find those lines and boundaries,
which discriminate and distinguish them. The objects are too fine to
remain long in the same aspect or situation; and must be apprehended in
an instant, by a superior penetration, derived from nature, and improved
by habit and reflexion. It becomes, therefore, no inconsiderable part of
science barely to know the different operations of the mind, to separate
them from each other, to class them under their proper heads, and to
correct all that seeming disorder, in which they lie involved, when made
the object of reflexion and enquiry. This talk of ordering and
distinguishing, which has no merit, when performed with regard to
external bodies, the objects of our senses, rises in its value, when
directed towards the operations of the mind, in proportion to the
difficulty and labour, which we meet with in performing it. And if we
can go no farther than this mental geography, or delineation of the
distinct parts and powers of the mind, it is at least a satisfaction to
go so far; and the more obvious this science may appear (and it is by no
means obvious) the more contemptible still must the ignorance of it be
esteemed, in all pretenders to learning and philosophy.

Nor can there remain any suspicion, that this science is uncertain and
chimerical; unless we should entertain such a scepticism as is entirely
subversive of all speculation, and even action. It cannot be doubted,
that the mind is endowed with several powers and faculties, that these
powers are distinct from each other, that what is really distinct to the
immediate perception may be distinguished by reflexion; and
consequently, that there is a truth and falsehood in all propositions on
this subject, and a truth and falsehood, which lie not beyond the
compass of human understanding. There are many obvious distinctions of
this kind, such as those between the will and understanding, the
imagination and passions, which fall within the comprehension of every
human creature; and the finer and more philosophical distinctions are no
less real and certain, though more difficult to be comprehended. Some
instances, especially late ones, of success in these enquiries, may give
us a juster notion of the certainty and solidity of this branch of
learning. And shall we esteem it worthy the labour of a philosopher to
give us a true system of the planets, and adjust the position and order
of those remote bodies; while we affect to overlook those, who, with so
much success, delineate the parts of the mind, in which we are so
intimately concerned?

9. But may we not hope, that philosophy, if cultivated with care, and
encouraged by the attention of the public, may carry its researches
still farther, and discover, at least in some degree, the secret springs
and principles, by which the human mind is actuated in its operations?
Astronomers had long contented themselves with proving, from the
phaenomena, the true motions, order, and magnitude of the heavenly
bodies: Till a philosopher, at last, arose, who seems, from the happiest
reasoning, to have also determined the laws and forces, by which the
revolutions of the planets are governed and directed. The like has been
performed with regard to other parts of nature. And there is no reason
to despair of equal success in our enquiries concerning the mental
powers and economy, if prosecuted with equal capacity and caution. It is
probable, that one operation and principle of the mind depends on
another; which, again, may be resolved into one more general and
universal: And how far these researches may possibly be carried, it will
be difficult for us, before, or even after, a careful trial, exactly to
determine. This is certain, that attempts of this kind are every day
made even by those who philosophize the most negligently: And nothing
can be more requisite than to enter upon the enterprize with thorough
care and attention; that, if it lie within the compass of human
understanding, it may at last be happily achieved; if not, it may,
however, be rejected with some confidence and security. This last
conclusion, surely, is not desirable; nor ought it to be embraced too
rashly. For how much must we diminish from the beauty and value of this
species of philosophy, upon such a supposition? Moralists have hitherto
been accustomed, when they considered the vast multitude and diversity
of those actions that excite our approbation or dislike, to search for
some common principle, on which this variety of sentiments might depend.
And though they have sometimes carried the matter too far, by their
passion for some one general principle; it must, however, be confessed,
that they are excusable in expecting to find some general principles,
into which all the vices and virtues were justly to be resolved. The
like has been the endeavour of critics, logicians, and even politicians:
Nor have their attempts been wholly unsuccessful; though perhaps longer
time, greater accuracy, and more ardent application may bring these
sciences still nearer their perfection. To throw up at once all
pretensions of this kind may justly be deemed more rash, precipitate,
and dogmatical, than even the boldest and most affirmative philosophy,
that has ever attempted to impose its crude dictates and principles
on mankind.

10. What though these reasonings concerning human nature seem abstract,
and of difficult comprehension? This affords no presumption of their
falsehood. On the contrary, it seems impossible, that what has hitherto
escaped so many wise and profound philosophers can be very obvious and
easy. And whatever pains these researches may cost us, we may think
ourselves sufficiently rewarded, not only in point of profit but of
pleasure, if, by that means, we can make any addition to our stock of
knowledge, in subjects of such unspeakable importance.

But as, after all, the abstractedness of these speculations is no
recommendation, but rather a disadvantage to them, and as this
difficulty may perhaps be surmounted by care and art, and the avoiding
of all unnecessary detail, we have, in the following enquiry, attempted
to throw some light upon subjects, from which uncertainty has hitherto
deterred the wise, and obscurity the ignorant. Happy, if we can unite
the boundaries of the different species of philosophy, by reconciling
profound enquiry with clearness, and truth with novelty! And still more
happy, if, reasoning in this easy manner, we can undermine the
foundations of an abstruse philosophy, which seems to have hitherto
served only as a shelter to superstition, and a cover to absurdity
and error!

SECTION II.

OF THE ORIGIN OF IDEAS.

11. Every one will readily allow, that there is a considerable
difference between the perceptions of the mind, when a man feels the
pain of excessive heat, or the pleasure of moderate warmth, and when he
afterwards recalls to his memory this sensation, or anticipates it by
his imagination. These faculties may mimic or copy the perceptions of
the senses; but they never can entirely reach the force and vivacity of
the original sentiment. The utmost we say of them, even when they
operate with greatest vigour, is, that they represent their object in so
lively a manner, that we could _almost_ say we feel or see it: But,
except the mind be disordered by disease or madness, they never can
arrive at such a pitch of vivacity, as to render these perceptions
altogether undistinguishable. All the colours of poetry, however
splendid, can never paint natural objects in such a manner as to make
the description be taken for a real landskip. The most lively thought is
still inferior to the dullest sensation.

We may observe a like distinction to run through all the other
perceptions of the mind. A man in a fit of anger, is actuated in a very
different manner from one who only thinks of that emotion. If you tell
me, that any person is in love, I easily understand your meaning, and
form a just conception of his situation; but never can mistake that
conception for the real disorders and agitations of the passion. When we
reflect on our past sentiments and affections, our thought is a faithful
mirror, and copies its objects truly; but the colours which it employs
are faint and dull, in comparison of those in which our original
perceptions were clothed. It requires no nice discernment or
metaphysical head to mark the distinction between them.

12. Here therefore we may divide all the perceptions of the mind into
two classes or species, which are distinguished by their different
degrees of force and vivacity. The less forcible and lively are commonly
denominated _Thoughts_ or _Ideas_. The other species want a name in our
language, and in most others; I suppose, because it was not requisite
for any, but philosophical purposes, to rank them under a general term
or appellation. Let us, therefore, use a little freedom, and call them
_Impressions_; employing that word in a sense somewhat different from
the usual. By the term _impression_, then, I mean all our more lively
perceptions, when we hear, or see, or feel, or love, or hate, or desire,
or will. And impressions are distinguished from ideas, which are the
less lively perceptions, of which we are conscious, when we reflect on
any of those sensations or movements above mentioned.

13. Nothing, at first view, may seem more unbounded than the thought of
man, which not only escapes all human power and authority, but is not
even restrained within the limits of nature and reality. To form
monsters, and join incongruous shapes and appearances, costs the
imagination no more trouble than to conceive the most natural and
familiar objects. And while the body is confined to one planet, along
which it creeps with pain and difficulty; the thought can in an instant
transport us into the most distant regions of the universe; or even
beyond the universe, into the unbounded chaos, where nature is supposed
to lie in total confusion. What never was seen, or heard of, may yet be
conceived; nor is any thing beyond the power of thought, except what
implies an absolute contradiction.

But though our thought seems to possess this unbounded liberty, we shall
find, upon a nearer examination, that it is really confined within very
narrow limits, and that all this creative power of the mind amounts to
no more than the faculty of compounding, transposing, augmenting, or
diminishing the materials afforded us by the senses and experience. When
we think of a golden mountain, we only join two consistent ideas,
_gold_, and _mountain_, with which we were formerly acquainted. A
virtuous horse we can conceive; because, from our own feeling, we can
conceive virtue; and this we may unite to the figure and shape of a
horse, which is an animal familiar to us. In short, all the materials of
thinking are derived either from our outward or inward sentiment: the
mixture and composition of these belongs alone to the mind and will. Or,
to express myself in philosophical language, all our ideas or more
feeble perceptions are copies of our impressions or more lively ones.

14. To prove this, the two following arguments will, I hope, be
sufficient. First, when we analyze our thoughts or ideas however
compounded or sublime, we always find that they resolve themselves into
such simple ideas as were copied from a precedent feeling or sentiment.
Even those ideas, which, at first view, seem the most wide of this
origin, are found, upon a nearer scrutiny, to be derived from it. The
idea of God, as meaning an infinitely intelligent, wise, and good Being,
arises from reflecting on the operations of our own mind, and
augmenting, without limit, those qualities of goodness and wisdom. We
may prosecute this enquiry to what length we please; where we shall
always find, that every idea which we examine is copied from a similar
impression. Those who would assert that this position is not universally
true nor without exception, have only one, and that an easy method of
refuting it; by producing that idea, which, in their opinion, is not
derived from this source. It will then be incumbent on us, if we would
maintain our doctrine, to produce the impression, or lively perception,
which corresponds to it.

15. Secondly. If it happen, from a defect of the organ, that a man is
not susceptible of any species of sensation, we always find that he is
as little susceptible of the correspondent ideas. A blind man can form
no notion of colours; a deaf man of sounds. Restore either of them that
sense in which he is deficient; by opening this new inlet for his
sensations, you also open an inlet for the ideas; and he finds no
difficulty in conceiving these objects. The case is the same, if the
object, proper for exciting any sensation, has never been applied to the
organ. A Laplander or Negro has no notion of the relish of wine. And
though there are few or no instances of a like deficiency in the mind,
where a person has never felt or is wholly incapable of a sentiment or
passion that belongs to his species; yet we find the same observation to
take place in a less degree. A man of mild manners can form no idea of
inveterate revenge or cruelty; nor can a selfish heart easily conceive
the heights of friendship and generosity. It is readily allowed, that
other beings may possess many senses of which we can have no conception;
because the ideas of them have never been introduced to us in the only
manner by which an idea can have access to the mind, to wit, by the
actual feeling and sensation.

16. There is, however, one contradictory phenomenon, which may prove
that it is not absolutely impossible for ideas to arise, independent of
their correspondent impressions. I believe it will readily be allowed,
that the several distinct ideas of colour, which enter by the eye, or
those of sound, which are conveyed by the ear, are really different from
each other; though, at the same time, resembling. Now if this be true of
different colours, it must be no less so of the different shades of the
same colour; and each shade produces a distinct idea, independent of the
rest. For if this should be denied, it is possible, by the continual
gradation of shades, to run a colour insensibly into what is most remote
from it; and if you will not allow any of the means to be different, you
cannot, without absurdity, deny the extremes to be the same. Suppose,
therefore, a person to have enjoyed his sight for thirty years, and to
have become perfectly acquainted with colours of all kinds except one
particular shade of blue, for instance, which it never has been his
fortune to meet with. Let all the different shades of that colour,
except that single one, be placed before him, descending gradually from
the deepest to the lightest; it is plain that he will perceive a blank,
where that shade is wanting, and will be sensible that there is a
greater distance in that place between the contiguous colours than in
any other. Now I ask, whether it be possible for him, from his own
imagination, to supply this deficiency, and raise up to himself the idea
of that particular shade, though it had never been conveyed to him by
his senses? I believe there are few but will be of opinion that he can:
and this may serve as a proof that the simple ideas are not always, in
every instance, derived from the correspondent impressions; though this
instance is so singular, that it is scarcely worth our observing, and
does not merit that for it alone we should alter our general maxim.

17. Here, therefore, is a proposition, which not only seems, in itself,
simple and intelligible; but, if a proper use were made of it, might
render every dispute equally intelligible, and banish all that jargon,
which has so long taken possession of metaphysical reasonings, and drawn
disgrace upon them. All ideas, especially abstract ones, are, naturally
faint and obscure: the mind has but a slender hold of them: they are apt
to be confounded with other resembling ideas; and when we have often
employed any term, though without a distinct meaning, we are apt to
imagine it has a determinate idea annexed to it. On the contrary, all
impressions, that is, all sensations, either outward or inward, are
strong and vivid: the limits between them are more exactly determined:
nor is it easy to fall into any error or mistake with regard to them.
When we entertain, therefore, any suspicion that a philosophical term is
employed without any meaning or idea (as is but too frequent), we need
but enquire, _from what impression is that supposed idea derived_? And
if it be impossible to assign any, this will serve to confirm our
suspicion. By bringing ideas into so clear a light we may reasonably
hope to remove all dispute, which may arise, concerning their nature and
reality.[1]

[1] It is probable that no more was meant by those, who denied
innate ideas, than that all ideas were copies of our
impressions; though it must be confessed, that the terms, which
they employed, were not chosen with such caution, nor so
exactly defined, as to prevent all mistakes about their
doctrine. For what is meant by _innate_? If innate be
equivalent to natural, then all the perceptions and ideas of
the mind must be allowed to be innate or natural, in whatever
sense we take the latter word, whether in opposition to what is
uncommon, artificial, or miraculous. If by innate be meant,
contemporary to our birth, the dispute seems to be frivolous;
nor is it worth while to enquire at what time thinking begins,
whether before, at, or after our birth. Again, the word _idea_,
seems to be commonly taken in a very loose sense, by LOCKE and
others; as standing for any of our perceptions, our sensations
and passions, as well as thoughts. Now in this sense, I should
desire to know, what can be meant by asserting, that self-love,
or resentment of injuries, or the passion between the sexes is
not innate!

But admitting these terms, _impressions_ and _ideas_, in the
sense above explained, and understanding by _innate_, what is
original or copied from no precedent perception, then may we
assert that all our impressions are innate, and our ideas
not innate.

To be ingenuous, I must own it to be my opinion, that LOCKE was
betrayed into this question by the schoolmen, who, making use
of undefined terms, draw out their disputes to a tedious
length, without ever touching the point in question. A like
ambiguity and circumlocution seem to run through that
philosopher's reasonings on this as well as most other
subjects.

SECTION III.

OF THE ASSOCIATION OF IDEAS.

18. It is evident that there is a principle of connexion between the
different thoughts or ideas of the mind, and that, in their appearance
to the memory or imagination, they introduce each other with a certain
degree of method and regularity. In our more serious thinking or
discourse this is so observable that any particular thought, which
breaks in upon the regular tract or chain of ideas, is immediately
remarked and rejected. And even in our wildest and most wandering
reveries, nay in our very dreams, we shall find, if we reflect, that the
imagination ran not altogether at adventures, but that there was still a
connexion upheld among the different ideas, which succeeded each other.
Were the loosest and freest conversation to be transcribed, there would
immediately be observed something which connected it in all its
transitions. Or where this is wanting, the person who broke the thread
of discourse might still inform you, that there had secretly revolved in
his mind a succession of thought, which had gradually led him from the
subject of conversation. Among different languages, even where we cannot
suspect the least connexion or communication, it is found, that the
words, expressive of ideas, the most compounded, do yet nearly
correspond to each other: a certain proof that the simple ideas,
comprehended in the compound ones, were bound together by some universal
principle, which had an equal influence on all mankind.

19. Though it be too obvious to escape observation, that different ideas
are connected together; I do not find that any philosopher has attempted
to enumerate or class all the principles of association; a subject,
however, that seems worthy of curiosity. To me, there appear to be only
three principles of connexion among ideas, namely, _Resemblance_,
_Contiguity_ in time or place, and _Cause or Effect_.

That these principles serve to connect ideas will not, I believe, be
much doubted. A picture naturally leads our thoughts to the original[2]:
the mention of one apartment in a building naturally introduces an
enquiry or discourse concerning the others[3]: and if we think of a
wound, we can scarcely forbear reflecting on the pain which follows
it[4]. But that this enumeration is complete, and that there are no
other principles of association except these, may be difficult to prove
to the satisfaction of the reader, or even to a man's own satisfaction.
All we can do, in such cases, is to run over several instances, and
examine carefully the principle which binds the different thoughts to
each other, never stopping till we render the principle as general as
possible[5]. The more instances we examine, and the more care we employ,
the more assurance shall we acquire, that the enumeration, which we form
from the whole, is complete and entire.

[2] Resemblance.

[3] Contiguity.

[4] Cause and effect.

[5] For instance, Contrast or Contrariety is also a connexion
among Ideas: but it may, perhaps, be considered as a mixture of
_Causation_ and _Resemblance_. Where two objects are contrary,
the one destroys the other; that is, the cause of its
annihilation, and the idea of the annihilation of an object,
implies the idea of its former existence.

SECTION IV.

SCEPTICAL DOUBTS CONCERNING THE OPERATIONS OF THE UNDERSTANDING.

PART I.

20. All the objects of human reason or enquiry may naturally be divided
into two kinds, to wit, _Relations of Ideas_, and _Matters of Fact_. Of
the first kind are the sciences of Geometry, Algebra, and Arithmetic;
and in short, every affirmation which is either intuitively or
demonstratively certain. _That the square of the hypothenuse is equal to
the square of the two sides_, is a proposition which expresses a
relation between these figures. _That three times five is equal to the
half of thirty_, expresses a relation between these numbers.
Propositions of this kind are discoverable by the mere operation of
thought, without dependence on what is anywhere existent in the
universe. Though there never were a circle or triangle in nature, the
truths demonstrated by Euclid would for ever retain their certainty
and evidence.

21. Matters of fact, which are the second objects of human reason, are
not ascertained in the same manner; nor is our evidence of their truth,
however great, of a like nature with the foregoing. The contrary of
every matter of fact is still possible; because it can never imply a
contradiction, and is conceived by the mind with the same facility and
distinctness, as if ever so conformable to reality. _That the sun will
not rise to-morrow_ is no less intelligible a proposition, and implies
no more contradiction than the affirmation, _that it will rise_. We
should in vain, therefore, attempt to demonstrate its falsehood. Were it
demonstratively false, it would imply a contradiction, and could never
be distinctly conceived by the mind.

It may, therefore, be a subject worthy of curiosity, to enquire what is
the nature of that evidence which assures us of any real existence and
matter of fact, beyond the present testimony of our senses, or the
records of our memory. This part of philosophy, it is observable, has
been little cultivated, either by the ancients or moderns; and therefore
our doubts and errors, in the prosecution of so important an enquiry,
may be the more excusable; while we march through such difficult paths
without any guide or direction. They may even prove useful, by exciting
curiosity, and destroying that implicit faith and security, which is the
bane of all reasoning and free enquiry. The discovery of defects in the
common philosophy, if any such there be, will not, I presume, be a
discouragement, but rather an incitement, as is usual, to attempt
something more full and satisfactory than has yet been proposed to
the public.

22. All reasonings concerning matter of fact seem to be founded on the
relation of _Cause and Effect_. By means of that relation alone we can
go beyond the evidence of our memory and senses. If you were to ask a
man, why he believes any matter of fact, which is absent; for instance,
that his friend is in the country, or in France; he would give you a
reason; and this reason would be some other fact; as a letter received
from him, or the knowledge of his former resolutions and promises. A man
finding a watch or any other machine in a desert island, would conclude
that there had once been men in that island. All our reasonings
concerning fact are of the same nature. And here it is constantly
supposed that there is a connexion between the present fact and that
which is inferred from it. Were there nothing to bind them together, the
inference would be entirely precarious. The hearing of an articulate
voice and rational discourse in the dark assures us of the presence of
some person: Why? because these are the effects of the human make and
fabric, and closely connected with it. If we anatomize all the other
reasonings of this nature, we shall find that they are founded on the
relation of cause and effect, and that this relation is either near or
remote, direct or collateral. Heat and light are collateral effects of
fire, and the one effect may justly be inferred from the other.

23. If we would satisfy ourselves, therefore, concerning the nature of
that evidence, which assures us of matters of fact, we must enquire how
we arrive at the knowledge of cause and effect.

I shall venture to affirm, as a general proposition, which admits of no
exception, that the knowledge of this relation is not, in any instance,
attained by reasonings _a priori_; but arises entirely from experience,
when we find that any particular objects are constantly conjoined with
each other. Let an object be presented to a man of ever so strong
natural reason and abilities; if that object be entirely new to him, he
will not be able, by the most accurate examination of its sensible
qualities, to discover any of its causes or effects. Adam, though his
rational faculties be supposed, at the very first, entirely perfect,
could not have inferred from the fluidity and transparency of water that
it would suffocate him, or from the light and warmth of fire that it
would consume him. No object ever discovers, by the qualities which
appear to the senses, either the causes which produced it, or the
effects which will arise from it; nor can our reason, unassisted by
experience, ever draw any inference concerning real existence and
matter of fact.

24. This proposition, _that causes and effects are discoverable, not by
reason but by experience_, will readily be admitted with regard to such
objects, as we remember to have once been altogether unknown to us;
since we must be conscious of the utter inability, which we then lay
under, of foretelling what would arise from them. Present two smooth
pieces of marble to a man who has no tincture of natural philosophy; he
will never discover that they will adhere together in such a manner as
to require great force to separate them in a direct line, while they
make so small a resistance to a lateral pressure. Such events, as bear
little analogy to the common course of nature, are also readily
confessed to be known only by experience; nor does any man imagine that
the explosion of gunpowder, or the attraction of a loadstone, could ever
be discovered by arguments _a priori_. In like manner, when an effect is
supposed to depend upon an intricate machinery or secret structure of
parts, we make no difficulty in attributing all our knowledge of it to
experience. Who will assert that he can give the ultimate reason, why
milk or bread is proper nourishment for a man, not for a lion or
a tiger?

But the same truth may not appear, at first sight, to have the same
evidence with regard to events, which have become familiar to us from
our first appearance in the world, which bear a close analogy to the
whole course of nature, and which are supposed to depend on the simple
qualities of objects, without any secret structure of parts. We are apt
to imagine that we could discover these effects by the mere operation of
our reason, without experience. We fancy, that were we brought on a
sudden into this world, we could at first have inferred that one
Billiard-ball would communicate motion to another upon impulse; and that
we needed not to have waited for the event, in order to pronounce with
certainty concerning it. Such is the influence of custom, that, where it
is strongest, it not only covers our natural ignorance, but even
conceals itself, and seems not to take place, merely because it is found
in the highest degree.

25. But to convince us that all the laws of nature, and all the
operations of bodies without exception, are known only by experience,
the following reflections may, perhaps, suffice. Were any object
presented to us, and were we required to pronounce concerning the
effect, which will result from it, without consulting past observation;
after what manner, I beseech you, must the mind proceed in this
operation? It must invent or imagine some event, which it ascribes to
the object as its effect; and it is plain that this invention must be
entirely arbitrary. The mind can never possibly find the effect in the
supposed cause, by the most accurate scrutiny and examination. For the
effect is totally different from the cause, and consequently can never
be discovered in it. Motion in the second Billiard-ball is a quite
distinct event from motion in the first; nor is there anything in the
one to suggest the smallest hint of the other. A stone or piece of metal
raised into the air, and left without any support, immediately falls:
but to consider the matter _a priori_, is there anything we discover in
this situation which can beget the idea of a downward, rather than an
upward, or any other motion, in the stone or metal? And as the first
imagination or invention of a particular effect, in all natural
operations, is arbitrary, where we consult not experience; so must we
also esteem the supposed tie or connexion between the cause and effect,
which binds them together, and renders it impossible that any other
effect could result from the operation of that cause. When I see, for
instance, a Billiard-ball moving in a straight line towards another;
even suppose motion in the second ball should by accident be suggested
to me, as the result of their contact or impulse; may I not conceive,
that a hundred different events might as well follow from that cause?
May not both these balls remain at absolute rest? May not the first ball
return in a straight line, or leap off from the second in any line or
direction? All these suppositions are consistent and conceivable. Why
then should we give the preference to one, which is no more consistent
or conceivable than the rest? All our reasonings _a priori_ will never
be able to show us any foundation for this preference.

In a word, then, every effect is a distinct event from its cause. It
could not, therefore, be discovered in the cause, and the first
invention or conception of it, _a priori_, must be entirely arbitrary.
And even after it is suggested, the conjunction of it with the cause
must appear equally arbitrary; since there are always many other
effects, which, to reason, must seem fully as consistent and natural. In
vain, therefore, should we pretend to determine any single event, or
infer any cause or effect, without the assistance of observation and
experience.

26. Hence we may discover the reason why no philosopher, who is rational
and modest, has ever pretended to assign the ultimate cause of any
natural operation, or to show distinctly the action of that power, which
produces any single effect in the universe. It is confessed, that the
utmost effort of human reason is to reduce the principles, productive of
natural phenomena, to a greater simplicity, and to resolve the many
particular effects into a few general causes, by means of reasonings
from analogy, experience, and observation. But as to the causes of these
general causes, we should in vain attempt their discovery; nor shall we
ever be able to satisfy ourselves, by any particular explication of
them. These ultimate springs and principles are totally shut up from
human curiosity and enquiry. Elasticity, gravity, cohesion of parts,
communication of motion by impulse; these are probably the ultimate
causes and principles which we shall ever discover in nature; and we may
esteem ourselves sufficiently happy, if, by accurate enquiry and
reasoning, we can trace up the particular phenomena to, or near to,
these general principles. The most perfect philosophy of the natural
kind only staves off our ignorance a little longer: as perhaps the most
perfect philosophy of the moral or metaphysical kind serves only to
discover larger portions of it. Thus the observation of human blindness
and weakness is the result of all philosophy, and meets us at every
turn, in spite of our endeavours to elude or avoid it.

27. Nor is geometry, when taken into the assistance of natural
philosophy, ever able to remedy this defect, or lead us into the
knowledge of ultimate causes, by all that accuracy of reasoning for
which it is so justly celebrated. Every part of mixed mathematics
proceeds upon the supposition that certain laws are established by
nature in her operations; and abstract reasonings are employed, either
to assist experience in the discovery of these laws, or to determine
their influence in particular instances, where it depends upon any
precise degree of distance and quantity. Thus, it is a law of motion,
discovered by experience, that the moment or force of any body in motion
is in the compound ratio or proportion of its solid contents and its
velocity; and consequently, that a small force may remove the greatest
obstacle or raise the greatest weight, if, by any contrivance or
machinery, we can increase the velocity of that force, so as to make it
an overmatch for its antagonist. Geometry assists us in the application
of this law, by giving us the just dimensions of all the parts and
figures which can enter into any species of machine; but still the
discovery of the law itself is owing merely to experience, and all the
abstract reasonings in the world could never lead us one step towards
the knowledge of it. When we reason _a priori_, and consider merely any
object or cause, as it appears to the mind, independent of all
observation, it never could suggest to us the notion of any distinct
object, such as its effect; much less, show us the inseparable and
inviolable connexion between them. A man must be very sagacious who
could discover by reasoning that crystal is the effect of heat, and ice
of cold, without being previously acquainted with the operation of these
qualities.

PART II.

28. But we have not yet attained any tolerable satisfaction with regard
to the question first proposed. Each solution still gives rise to a new
question as difficult as the foregoing, and leads us on to farther
enquiries. When it is asked, _What is the nature of all our reasonings
concerning matter of fact?_ the proper answer seems to be, that they are
founded on the relation of cause and effect. When again it is asked,
_What is the foundation of all our reasonings and conclusions concerning
that relation?_ it may be replied in one word, Experience. But if we
still carry on our sifting humour, and ask, _What is the foundation of
all conclusions from experience?_ this implies a new question, which may
be of more difficult solution and explication. Philosophers, that give
themselves airs of superior wisdom and sufficiency, have a hard task
when they encounter persons of inquisitive dispositions, who push them
from every corner to which they retreat, and who are sure at last to
bring them to some dangerous dilemma. The best expedient to prevent this
confusion, is to be modest in our pretensions; and even to discover the
difficulty ourselves before it is objected to us. By this means, we may
make a kind of merit of our very ignorance.

I shall content myself, in this section, with an easy task, and shall
pretend only to give a negative answer to the question here proposed. I
say then, that, even after we have experience of the operations of cause
and effect, our conclusions from that experience are _not_ founded on
reasoning, or any process of the understanding. This answer we must
endeavour both to explain and to defend.

29. It must certainly be allowed, that nature has kept us at a great
distance from all her secrets, and has afforded us only the knowledge of
a few superficial qualities of objects; while she conceals from us those
powers and principles on which the influence of those objects entirely
depends. Our senses inform us of the colour, weight, and consistence of
bread; but neither sense nor reason can ever inform us of those
qualities which fit it for the nourishment and support of a human body.
Sight or feeling conveys an idea of the actual motion of bodies; but as
to that wonderful force or power, which would carry on a moving body for
ever in a continued change of place, and which bodies never lose but by
communicating it to others; of this we cannot form the most distant
conception. But notwithstanding this ignorance of natural powers[6] and
principles, we always presume, when we see like sensible qualities, that
they have like secret powers, and expect that effects, similar to those
which we have experienced, will follow from them. If a body of like
colour and consistence with that bread, which we have formerly eat, be
presented to us, we make no scruple of repeating the experiment, and
foresee, with certainty, like nourishment and support. Now this is a
process of the mind or thought, of which I would willingly know the
foundation. It is allowed on all hands that there is no known connexion
between the sensible qualities and the secret powers; and consequently,
that the mind is not led to form such a conclusion concerning their
constant and regular conjunction, by anything which it knows of their
nature. As to past _Experience_, it can be allowed to give _direct_ and
_certain_ information of those precise objects only, and that precise
period of time, which fell under its cognizance: but why this experience
should be extended to future times, and to other objects, which for
aught we know, may be only in appearance similar; this is the main
question on which I would insist. The bread, which I formerly eat,
nourished me; that is, a body of such sensible qualities was, at that
time, endued with such secret powers: but does it follow, that other
bread must also nourish me at another time, and that like sensible
qualities must always be attended with like secret powers? The
consequence seems nowise necessary. At least, it must be acknowledged
that there is here a consequence drawn by the mind; that there is a
certain step taken; a process of thought, and an inference, which wants
to be explained. These two propositions are far from being the same, _I
have found that such an object has always been attended with such an
effect_, and _I foresee, that other objects, which are, in appearance,
similar, will be attended with similar effects_. I shall allow, if you
please, that the one proposition may justly be inferred from the other:
I know, in fact, that it always is inferred. But if you insist that the
inference is made by a chain of reasoning, I desire you to produce that
reasoning. The connexion between these propositions is not intuitive.
There is required a medium, which may enable the mind to draw such an
inference, if indeed it be drawn by reasoning and argument. What that
medium is, I must confess, passes my comprehension; and it is incumbent
on those to produce it, who assert that it really exists, and is the
origin of all our conclusions concerning matter of fact.

[6] The word, Power, is here used in a loose and popular sense.
The more accurate explication of it would give additional
evidence to this argument. See Sect. 7.

30. This negative argument must certainly, in process of time, become
altogether convincing, if many penetrating and able philosophers shall
turn their enquiries this way and no one be ever able to discover any
connecting proposition or intermediate step, which supports the
understanding in this conclusion. But as the question is yet new, every
reader may not trust so far to his own penetration, as to conclude,
because an argument escapes his enquiry, that therefore it does not
really exist. For this reason it may be requisite to venture upon a more
difficult task; and enumerating all the branches of human knowledge,
endeavour to show that none of them can afford such an argument.

All reasonings may be divided into two kinds, namely, demonstrative
reasoning, or that concerning relations of ideas, and moral reasoning,
or that concerning matter of tact and existence. That there are no
demonstrative arguments in the case seems evident; since it implies no
contradiction that the course of nature may change, and that an object,
seemingly like those which we have experienced, may be attended with
different or contrary effects. May I not clearly and distinctly conceive
that a body, falling from the clouds, and which, in all other respects,
resembles snow, has yet the taste of salt or feeling of fire? Is there
any more intelligible proposition than to affirm, that all the trees
will flourish in December and January, and decay in May and June? Now
whatever is intelligible, and can be distinctly conceived, implies no
contradiction, and can never be proved false by any demonstrative
argument or abstract reasoning _ priori_.

If we be, therefore, engaged by arguments to put trust in past
experience, and make it the standard of our future judgement, these
arguments must be probable only, or such as regard matter of fact and
real existence, according to the division above mentioned. But that
there is no argument of this kind, must appear, if our explication of
that species of reasoning be admitted as solid and satisfactory. We have
said that all arguments concerning existence are founded on the relation
of cause and effect; that our knowledge of that relation is derived
entirely from experience; and that all our experimental conclusions
proceed upon the supposition that the future will be conformable to the
past. To endeavour, therefore, the proof of this last supposition by
probable arguments, or arguments regarding existence, must be evidently
going in a circle, and taking that for granted, which is the very point
in question.

31. In reality, all arguments from experience are founded on the
similarity which we discover among natural objects, and by which we are
induced to expect effects similar to those which we have found to follow
from such objects. And though none but a fool or madman will ever
pretend to dispute the authority of experience, or to reject that great
guide of human life, it may surely be allowed a philosopher to have so
much curiosity at least as to examine the principle of human nature,
which gives this mighty authority to experience, and makes us draw
advantage from that similarity which nature has placed among different
objects. From causes which appear _similar_ we expect similar effects.
This is the sum of all our experimental conclusions. Now it seems
evident that, if this conclusion were formed by reason, it would be as
perfect at first, and upon one instance, as after ever so long a course
of experience. But the case is far otherwise. Nothing so like as eggs;
yet no one, on account of this appearing similarity, expects the same
taste and relish in all of them. It is only after a long course of
uniform experiments in any kind, that we attain a firm reliance and
security with regard to a particular event. Now where is that process of
reasoning which, from one instance, draws a conclusion, so different
from that which it infers from a hundred instances that are nowise
different from that single one? This question I propose as much for the
sake of information, as with an intention of raising difficulties. I
cannot find, I cannot imagine any such reasoning. But I keep my mind
still open to instruction, if any one will vouchsafe to bestow it on me.

32. Should it be said that, from a number of uniform experiments, we
_infer_ a connexion between the sensible qualities and the secret
powers; this, I must confess, seems the same difficulty, couched in
different terms. The question still recurs, on what process of argument
this _inference_ is founded? Where is the medium, the interposing ideas,
which join propositions so very wide of each other? It is confessed that
the colour, consistence, and other sensible qualities of bread appear
not, of themselves, to have any connexion with the secret powers of
nourishment and support. For otherwise we could infer these secret
powers from the first appearance of these sensible qualities, without
the aid of experience; contrary to the sentiment of all philosophers,
and contrary to plain matter of fact. Here, then, is our natural state
of ignorance with regard to the powers and influence of all objects. How
is this remedied by experience? It only shows us a number of uniform
effects, resulting from certain objects, and teaches us that those
particular objects, at that particular time, were endowed with such
powers and forces. When a new object, endowed with similar sensible
qualities, is produced, we expect similar powers and forces, and look
for a like effect. From a body of like colour and consistence with bread
we expect like nourishment and support. But this surely is a step or
progress of the mind, which wants to be explained. When a man says, _I
have found, in all past instances, such sensible qualities conjoined
with such secret powers_. And when he says, _Similar sensible qualities
will always be conjoined with similar secret powers_, he is not guilty
of a tautology, nor are these propositions in any respect the same. You
say that the one proposition is an inference from the other. But you
must confess that the inference is not intuitive; neither is it
demonstrative: Of what nature is it, then? To say it is experimental, is
begging the question. For all inferences from experience suppose, as
their foundation, that the future will resemble the past, and that
similar powers will be conjoined with similar sensible qualities. If
there be any suspicion that the course of nature may change, and that
the past may be no rule for the future, all experience becomes useless,
and can give rise to no inference or conclusion. It is impossible,
therefore, that any arguments from experience can prove this resemblance
of the past to the future; since all these arguments are founded on the
supposition of that resemblance. Let the course of things be allowed
hitherto ever so regular; that alone, without some new argument or
inference, proves not that, for the future, it will continue so. In vain
do you pretend to have learned the nature of bodies from your past
experience. Their secret nature, and consequently all their effects and
influence, may change, without any change in their sensible qualities.
This happens sometimes, and with regard to some objects: Why may it not
happen always, and with regard to all objects? What logic, what process
of argument secures you against this supposition? My practice, you say,
refutes my doubts. But you mistake the purport of my question. As an
agent, I am quite satisfied in the point; but as a philosopher, who has
some share of curiosity, I will not say scepticism, I want to learn the
foundation of this inference. No reading, no enquiry has yet been able
to remove my difficulty, or give me satisfaction in a matter of such
importance. Can I do better than propose the difficulty to the public,
even though, perhaps, I have small hopes of obtaining a solution? We
shall at least, by this means, be sensible of our ignorance, if we do
not augment our knowledge.

33. I must confess that a man is guilty of unpardonable arrogance who
concludes, because an argument has escaped his own investigation, that
therefore it does not really exist. I must also confess that, though all
the learned, for several ages, should have employed themselves in
fruitless search upon any subject, it may still, perhaps, be rash to
conclude positively that the subject must, therefore, pass all human
comprehension. Even though we examine all the sources of our knowledge,
and conclude them unfit for such a subject, there may still remain a
suspicion, that the enumeration is not complete, or the examination not
accurate. But with regard to the present subject, there are some
considerations which seem to remove all this accusation of arrogance or
suspicion of mistake.

It is certain that the most ignorant and stupid peasants--nay infants,
nay even brute beasts--improve by experience, and learn the qualities of
natural objects, by observing the effects which result from them. When a
child has felt the sensation of pain from touching the flame of a
candle, he will be careful not to put his hand near any candle; but will
expect a similar effect from a cause which is similar in its sensible
qualities and appearance. If you assert, therefore, that the
understanding of the child is led into this conclusion by any process of
argument or ratiocination, I may justly require you to produce that
argument; nor have you any pretence to refuse so equitable a demand. You
cannot say that the argument is abstruse, and may possibly escape your
enquiry; since you confess that it is obvious to the capacity of a mere
infant. If you hesitate, therefore, a moment, or if, after reflection,
you produce any intricate or profound argument, you, in a manner, give
up the question, and confess that it is not reasoning which engages us
to suppose the past resembling the future, and to expect similar effects
from causes which are, to appearance, similar. This is the proposition
which I intended to enforce in the present section. If I be right, I
pretend not to have made any mighty discovery. And if I be wrong, I must
acknowledge myself to be indeed a very backward scholar; since I cannot
now discover an argument which, it seems, was perfectly familiar to me
long before I was out of my cradle.

SECTION V.

SCEPTICAL SOLUTION OF THESE DOUBTS.

PART I.

34. The passion for philosophy, like that for religion, seems liable to
this inconvenience, that, though it aims at the correction of our
manners, and extirpation of our vices, it may only serve, by imprudent
management, to foster a predominant inclination, and push the mind, with
more determined resolution, towards that side which already _draws_ too
much, by the bias and propensity of the natural temper. It is certain
that, while we aspire to the magnanimous firmness of the philosophic
sage, and endeavour to confine our pleasures altogether within our own
minds, we may, at last, render our philosophy like that of Epictetus,
and other _Stoics_, only a more refined system of selfishness, and
reason ourselves out of all virtue as well as social enjoyment. While we
study with attention the vanity of human life, and turn all our thoughts
towards the empty and transitory nature of riches and honours, we are,
perhaps, all the while flattering our natural indolence, which, hating
the bustle of the world, and drudgery of business, seeks a pretence of
reason to give itself a full and uncontrolled indulgence. There is,
however, one species of philosophy which seems little liable to this
inconvenience, and that because it strikes in with no disorderly passion
of the human mind, nor can mingle itself with any natural affection or
propensity; and that is the Academic or Sceptical philosophy. The
academics always talk of doubt and suspense of judgement, of danger in
hasty determinations, of confining to very narrow bounds the enquiries
of the understanding, and of renouncing all speculations which lie not
within the limits of common life and practice. Nothing, therefore, can
be more contrary than such a philosophy to the supine indolence of the
mind, its rash arrogance, its lofty pretensions, and its superstitious
credulity. Every passion is mortified by it, except the love of truth;
and that passion never is, nor can be, carried to too high a degree. It
is surprising, therefore, that this philosophy, which, in almost every
instance, must be harmless and innocent, should be the subject of so
much groundless reproach and obloquy. But, perhaps, the very
circumstance which renders it so innocent is what chiefly exposes it to
the public hatred and resentment. By flattering no irregular passion, it
gains few partizans: By opposing so many vices and follies, it raises to
itself abundance of enemies, who stigmatize it as libertine profane, and
irreligious.

Nor need we fear that this philosophy, while it endeavours to limit our
enquiries to common life, should ever undermine the reasonings of common
life, and carry its doubts so far as to destroy all action, as well as
speculation. Nature will always maintain her rights, and prevail in the
end over any abstract reasoning whatsoever. Though we should conclude,
for instance, as in the foregoing section, that, in all reasonings from
experience, there is a step taken by the mind which is not supported by
any argument or process of the understanding; there is no danger that
these reasonings, on which almost all knowledge depends, will ever be
affected by such a discovery. If the mind be not engaged by argument to
make this step, it must be induced by some other principle of equal
weight and authority; and that principle will preserve its influence as
long as human nature remains the same. What that principle is may well
be worth the pains of enquiry.

35. Suppose a person, though endowed with the strongest faculties of
reason and reflection, to be brought on a sudden into this world; he
would, indeed, immediately observe a continual succession of objects,
and one event following another; but he would not be able to discover
anything farther. He would not, at first, by any reasoning, be able to
reach the idea of cause and effect; since the particular powers, by
which all natural operations are performed, never appear to the senses;
nor is it reasonable to conclude, merely because one event, in one
instance, precedes another, that therefore the one is the cause, the
other the effect. Their conjunction may be arbitrary and casual. There
may be no reason to infer the existence of one from the appearance of
the other. And in a word, such a person, without more experience, could
never employ his conjecture or reasoning concerning any matter of fact,
or be assured of anything beyond what was immediately present to his
memory and senses.

Suppose, again, that he has acquired more experience, and has lived so
long in the world as to have observed familiar objects or events to be
constantly conjoined together; what is the consequence of this
experience? He immediately infers the existence of one object from the
appearance of the other. Yet he has not, by all his experience, acquired
any idea or knowledge of the secret power by which the one object
produces the other; nor is it, by any process of reasoning, he is
engaged to draw this inference. But still he finds himself determined to
draw it: And though he should be convinced that his understanding has no
part in the operation, he would nevertheless continue in the same course
of thinking. There is some other principle which determines him to form
such a conclusion.

36. This principle is Custom or Habit. For wherever the repetition of
any particular act or operation produces a propensity to renew the same
act or operation, without being impelled by any reasoning or process of
the understanding, we always say, that this propensity is the effect of
_Custom_. By employing that word, we pretend not to have given the
ultimate reason of such a propensity. We only point out a principle of
human nature, which is universally acknowledged, and which is well known
by its effects. Perhaps we can push our enquiries no farther, or pretend
to give the cause of this cause; but must rest contented with it as the
ultimate principle, which we can assign, of all our conclusions from
experience. It is sufficient satisfaction, that we can go so far,
without repining at the narrowness of our faculties because they will
carry us no farther. And it is certain we here advance a very
intelligible proposition at least, if not a true one, when we assert
that, after the constant conjunction of two objects--heat and flame, for
instance, weight and solidity--we are determined by custom alone to
expect the one from the appearance of the other. This hypothesis seems
even the only one which explains the difficulty, why we draw, from a
thousand instances, an inference which we are not able to draw from one
instance, that is, in no respect, different from them. Reason is
incapable of any such variation. The conclusions which it draws from
considering one circle are the same which it would form upon surveying
all the circles in the universe. But no man, having seen only one body
move after being impelled by another, could infer that every other body
will move after a like impulse. All inferences from experience,
therefore, are effects of custom, not of reasoning[7].

[7] Nothing is more useful than for writers, even, on _moral_,
_political_, or _physical_ subjects, to distinguish between
_reason_ and _experience_, and to suppose, that these species
of argumentation are entirely different from each other. The
former are taken for the mere result of our intellectual
faculties, which, by considering _ priori_ the nature of
things, and examining the effects, that must follow from their
operation, establish particular principles of science and
philosophy. The latter are supposed to be derived entirely from
sense and observation, by which we learn what has actually
resulted from the operation of particular objects, and are
thence able to infer, what will, for the future, result from
them. Thus, for instance, the limitations and restraints of
civil government, and a legal constitution, may be defended,
either from _reason_, which reflecting on the great frailty and
corruption of human nature, teaches, that no man can safely be
trusted with unlimited authority; or from _experience_ and
history, which inform us of the enormous abuses, that ambition,
in every age and country, has been found to make of so
imprudent a confidence.

The same distinction between reason and experience is
maintained in all our deliberations concerning the conduct of
life; while the experienced statesman, general, physician, or
merchant is trusted and followed; and the unpractised novice,
with whatever natural talents endowed, neglected and despised.
Though it be allowed, that reason may form very plausible
conjectures with regard to the consequences of such a
particular conduct in such particular circumstances; it is
still supposed imperfect, without the assistance of experience,
which is alone able to give stability and certainty to the
maxims, derived from study and reflection.

But notwithstanding that this distinction be thus universally
received, both in the active speculative scenes of life, I
shall not scruple to pronounce, that it is, at bottom,
erroneous, at least, superficial.

If we examine those arguments, which, in any of the sciences
above mentioned, are supposed to be the mere effects of
reasoning and reflection, they will be found to terminate, at
last, in some general principle or conclusion, for which we can
assign no reason but observation and experience. The only
difference between them and those maxims, which are vulgarly
esteemed the result of pure experience, is, that the former
cannot be established without some process of thought, and some
reflection on what we have observed, in order to distinguish
its circumstances, and trace its consequences: Whereas in the
latter, the experienced event is exactly and fully familiar to
that which we infer as the result of any particular situation.
The history of a TIBERIUS or a NERO makes us dread a like
tyranny, were our monarchs freed from the restraints of laws
and senates: But the observation of any fraud or cruelty in
private life is sufficient, with the aid of a little thought,
to give us the same apprehension; while it serves as an
instance of the general corruption of human nature, and shows
us the danger which we must incur by reposing an entire
confidence in mankind. In both cases, it is experience which is
ultimately the foundation of our inference and conclusion.

There is no man so young and unexperienced, as not to have
formed, from observation, many general and just maxims
concerning human affairs and the conduct of life; but it must
be confessed, that, when a man comes to put these in practice,
he will be extremely liable to error, till time and farther
experience both enlarge these maxims, and teach him their
proper use and application. In every situation or incident,
there are many particular and seemingly minute circumstances,
which the man of greatest talent is, at first, apt to overlook,
though on them the justness of his conclusions, and
consequently the prudence of his conduct, entirely depend. Not
to mention, that, to a young beginner, the general observations
and maxims occur not always on the proper occasions, nor can be
immediately applied with due calmness and distinction. The
truth is, an unexperienced reasoner could be no reasoner at
all, were he absolutely unexperienced; and when we assign that
character to any one, we mean it only in a comparative sense,
and suppose him possessed of experience, in a smaller and more
imperfect degree.

Custom, then, is the great guide of human life. It is that principle
alone which renders our experience useful to us, and makes us expect,
for the future, a similar train of events with those which have appeared
in the past.

Without the influence of custom, we should be entirely ignorant of every
matter of fact beyond what is immediately present to the memory and
senses. We should never know how to adjust means to ends, or to employ
our natural powers in the production of any effect. There would be an
end at once of all action, as well as of the chief part of speculation.

37. But here it may be proper to remark, that though our conclusions
from experience carry us beyond our memory and senses, and assure us of
matters of fact which happened in the most distant places and most
remote ages, yet some fact must always be present to the senses or
memory, from which we may first proceed in drawing these conclusions. A
man, who should find in a desert country the remains of pompous
buildings, would conclude that the country had, in ancient times, been
cultivated by civilized inhabitants; but did nothing of this nature
occur to him, he could never form such an inference. We learn the events
of former ages from history; but then we must peruse the volumes in
which this instruction is contained, and thence carry up our inferences
from one testimony to another, till we arrive at the eyewitnesses and
spectators of these distant events. In a word, if we proceed not upon
some fact, present to the memory or senses, our reasonings would be
merely hypothetical; and however the particular links might be connected
with each other, the whole chain of inferences would have nothing to
support it, nor could we ever, by its means, arrive at the knowledge of
any real existence. If I ask why you believe any particular matter of
fact, which you relate, you must tell me some reason; and this reason
will be some other fact, connected with it. But as you cannot proceed
after this manner, _in infinitum_, you must at last terminate in some
fact, which is present to your memory or senses; or must allow that your
belief is entirely without foundation.

38. What, then, is the conclusion of the whole matter? A simple one;
though, it must be confessed, pretty remote from the common theories of
philosophy. All belief of matter of fact or real existence is derived
merely from some object, present to the memory or senses, and a
customary conjunction between that and some other object. Or in other
words; having found, in many instances, that any two kinds of
objects--flame and heat, snow and cold--have always been conjoined
together; if flame or snow be presented anew to the senses, the mind is
carried by custom to expect heat or cold, and to _believe_ that such a
quality does exist, and will discover itself upon a nearer approach.
This belief is the necessary result of placing the mind in such
circumstances. It is an operation of the soul, when we are so situated,
as unavoidable as to feel the passion of love, when we receive benefits;
or hatred, when we meet with injuries. All these operations are a
species of natural instincts, which no reasoning or process of the
thought and understanding is able either to produce or to prevent.

At this point, it would be very allowable for us to stop our
philosophical researches. In most questions we can never make a single
step farther; and in all questions we must terminate here at last, after
our most restless and curious enquiries. But still our curiosity will be
pardonable, perhaps commendable, if it carry us on to still farther
researches, and make us examine more accurately the nature of this
_belief_, and of the _customary conjunction_, whence it is derived. By
this means we may meet with some explications and analogies that will
give satisfaction; at least to such as love the abstract sciences, and
can be entertained with speculations, which, however accurate, may still
retain a degree of doubt and uncertainty. As to readers of a different
taste; the remaining part of this section is not calculated for them,
and the following enquiries may well be understood, though it be
neglected.

PART II.

39. Nothing is more free than the imagination of man; and though it
cannot exceed that original stock of ideas furnished by the internal and
external senses, it has unlimited power of mixing, compounding,
separating, and dividing these ideas, in all the varieties of fiction
and vision. It can feign a train of events, with all the appearance of
reality, ascribe to them a particular time and place, conceive them as
existent, and paint them out to itself with every circumstance, that
belongs to any historical fact, which it believes with the greatest
certainty. Wherein, therefore, consists the difference between such a
fiction and belief? It lies not merely in any peculiar idea, which is
annexed to such a conception as commands our assent, and which is
wanting to every known fiction. For as the mind has authority over all
its ideas, it could voluntarily annex this particular idea to any
fiction, and consequently be able to believe whatever it pleases;
contrary to what we find by daily experience. We can, in our conception,
join the head of a man to the body of a horse; but it is not in our
power to believe that such an animal has ever really existed.

It follows, therefore, that the difference between _fiction_ and
_belief_ lies in some sentiment or feeling, which is annexed to the
latter, not to the former, and which depends not on the will, nor can be
commanded at pleasure. It must be excited by nature, like all other
sentiments; and must arise from the particular situation, in which the
mind is placed at any particular juncture. Whenever any object is
presented to the memory or senses, it immediately, by the force of
custom, carries the imagination to conceive that object, which is
usually conjoined to it; and this conception is attended with a feeling
or sentiment, different from the loose reveries of the fancy. In this
consists the whole nature of belief. For as there is no matter of fact
which we believe so firmly that we cannot conceive the contrary, there
would be no difference between the conception assented to and that which
is rejected, were it not for some sentiment which distinguishes the one
from the other. If I see a billiard-ball moving towards another, on a
smooth table, I can easily conceive it to stop upon contact. This
conception implies no contradiction; but still it feels very differently
from that conception by which I represent to myself the impulse and the
communication of motion from one ball to another.

40. Were we to attempt a _definition_ of this sentiment, we should,
perhaps, find it a very difficult, if not an impossible task; in the
same manner as if we should endeavour to define the feeling of cold or
passion of anger, to a creature who never had any experience of these
sentiments. Belief is the true and proper name of this feeling; and no
one is ever at a loss to know the meaning of that term; because every
man is every moment conscious of the sentiment represented by it. It may
not, however, be improper to attempt a _description_ of this sentiment;
in hopes we may, by that means, arrive at some analogies, which may
afford a more perfect explication of it. I say, then, that belief is
nothing but a more vivid, lively, forcible, firm, steady conception of
an object, than what the imagination alone is ever able to attain. This
variety of terms, which may seem so unphilosophical, is intended only to
express that act of the mind, which renders realities, or what is taken
for such, more present to us than fictions, causes them to weigh more in
the thought, and gives them a superior influence on the passions and
imagination. Provided we agree about the thing, it is needless to
dispute about the terms. The imagination has the command over all its
ideas, and can join and mix and vary them, in all the ways possible. It
may conceive fictitious objects with all the circumstances of place and
time. It may set them, in a manner, before our eyes, in their true
colours, just as they might have existed. But as it is impossible that
this faculty of imagination can ever, of itself, reach belief, it is
evident that belief consists not in the peculiar nature or order of
ideas, but in the _manner_ of their conception, and in their _feeling_
to the mind. I confess, that it is impossible perfectly to explain this
feeling or manner of conception. We may make use of words which express
something near it. But its true and proper name, as we observed before,
is _belief_; which is a term that every one sufficiently understands in
common life. And in philosophy, we can go no farther than assert, that
_belief_ is something felt by the mind, which distinguishes the ideas of
the judgement from the fictions of the imagination. It gives them more
weight and influence; makes them appear of greater importance; enforces
them in the mind; and renders them the governing principle of our
actions. I hear at present, for instance, a person's voice, with whom I
am acquainted; and the sound comes as from the next room. This
impression of my senses immediately conveys my thought to the person,
together with all the surrounding objects. I paint them out to myself as
existing at present, with the same qualities and relations, of which I
formerly knew them possessed. These ideas take faster hold of my mind
than ideas of an enchanted castle. They are very different to the
feeling, and have a much greater influence of every kind, either to give
pleasure or pain, joy or sorrow.

Let us, then, take in the whole compass of this doctrine, and allow,
that the sentiment of belief is nothing but a conception more intense
and steady than what attends the mere fictions of the imagination, and
that this _manner_ of conception arises from a customary conjunction of
the object with something present to the memory or senses: I believe
that it will not be difficult, upon these suppositions, to find other
operations of the mind analogous to it, and to trace up these phenomena
to principles still more general.

41. We have already observed that nature has established connexions
among particular ideas, and that no sooner one idea occurs to our
thoughts than it introduces its correlative, and carries our attention
towards it, by a gentle and insensible movement. These principles of
connexion or association we have reduced to three, namely,
_Resemblance_, _Contiguity_ and _Causation_; which are the only bonds
that unite our thoughts together, and beget that regular train of
reflection or discourse, which, in a greater or less degree, takes place
among all mankind. Now here arises a question, on which the solution of
the present difficulty will depend. Does it happen, in all these
relations, that, when one of the objects is presented to the senses or
memory, the mind is not only carried to the conception of the
correlative, but reaches a steadier and stronger conception of it than
what otherwise it would have been able to attain? This seems to be the
case with that belief which arises from the relation of cause and
effect. And if the case be the same with the other relations or
principles of associations, this may be established as a general law,
which takes place in all the operations of the mind.

We may, therefore, observe, as the first experiment to our present
purpose, that, upon the appearance of the picture of an absent friend,
our idea of him is evidently enlivened by the _resemblance_, and that
every passion, which that idea occasions, whether of joy or sorrow,
acquires new force and vigour. In producing this effect, there concur
both a relation and a present impression. Where the picture bears him no
resemblance, at least was not intended for him, it never so much as
conveys our thought to him: And where it is absent, as well as the
person, though the mind may pass from the thought of the one to that of
the other, it feels its idea to be rather weakened than enlivened by
that transition. We take a pleasure in viewing the picture of a friend,
when it is set before us; but when it is removed, rather choose to
consider him directly than by reflection in an image, which is equally
distant and obscure.

The ceremonies of the Roman Catholic religion may be considered as
instances of the same nature. The devotees of that superstition usually
plead in excuse for the mummeries, with which they are upbraided, that
they feel the good effect of those external motions, and postures, and
actions, in enlivening their devotion and quickening their fervour,
which otherwise would decay, if directed entirely to distant and
immaterial objects. We shadow out the objects of our faith, say they, in
sensible types and images, and render them more present to us by the
immediate presence of these types, than it is possible for us to do
merely by an intellectual view and contemplation. Sensible objects have
always a greater influence on the fancy than any other; and this
influence they readily convey to those ideas to which they are related,
and which they resemble. I shall only infer from these practices, and
this reasoning, that the effect of resemblance in enlivening the ideas
is very common; and as in every case a resemblance and a present
impression must concur, we are abundantly supplied with experiments to
prove the reality of the foregoing principle.

42. We may add force to these experiments by others of a different kind,
in considering the effects of _contiguity_ as well as of _resemblance_.
It is certain that distance diminishes the force of every idea, and
that, upon our approach to any object; though it does not discover
itself to our senses; it operates upon the mind with an influence, which
imitates an immediate impression. The thinking on any object readily
transports the mind to what is contiguous; but it is only the actual
presence of an object, that transports it with a superior vivacity. When
I am a few miles from home, whatever relates to it touches me more
nearly than when I am two hundred leagues distant; though even at that
distance the reflecting on any thing in the neighbourhood of my friends
or family naturally produces an idea of them. But as in this latter
case, both the objects of the mind are ideas; notwithstanding there is
an easy transition between them; that transition alone is not able to
give a superior vivacity to any of the ideas, for want of some immediate
impression[8].

[8] 'Naturane nobis, inquit, datum dicam, an errore quodam, ut,
cum ea loca videamus, in quibus memoria dignos viros
acceperimus multum esse versatos, magis moveamur, quam siquando
eorum ipsorum aut facta audiamus aut scriptum aliquod legamus?
Velut ego nunc moveor. Venit enim mihi Plato in mentem, quera
accepimus primum hic disputare solitum: cuius etiam illi
hortuli propinqui non memoriam solum mihi afferunt, sed ipsum
videntur in conspectu meo hic ponere. Hic Speusippus, hic
Xenocrates, hic eius auditor Polemo; cuius ipsa illa sessio
fuit, quam videmus. Equidem etiam curiam nostram, Hostiliam
dico, non hanc novam, quae mihi minor esse videtur postquam est
maior, solebam intuens, Scipionem, Catonem, Laelium, nostrum
vero in primis avum cogitare. Tanta vis admonitionis est in
locis; ut non sine causa ex his memoriae deducta sit
disciplina.'

_Cicero de Finibus_. Lib. v.

43. No one can doubt but causation has the same influence as the other
two relations of resemblance and contiguity. Superstitious people are
fond of the reliques of saints and holy men, for the same reason, that
they seek after types or images, in order to enliven their devotion, and
give them a more intimate and strong conception of those exemplary
lives, which they desire to imitate. Now it is evident, that one of the
best reliques, which a devotee could procure, would be the handywork of
a saint; and if his cloaths and furniture are ever to be considered in
this light, it is because they were once at his disposal, and were moved
and affected by him; in which respect they are to be considered as
imperfect effects, and as connected with him by a shorter chain of
consequences than any of those, by which we learn the reality of his
existence.

Suppose, that the son of a friend, who had been long dead or absent,
were presented to us; it is evident, that this object would instantly
revive its correlative idea, and recal to our thoughts all past
intimacies and familiarities, in more lively colours than they would
otherwise have appeared to us. This is another phaenomenon, which seems
to prove the principle above mentioned.

44. We may observe, that, in these phaenomena, the belief of the
correlative object is always presupposed; without which the relation
could have no effect. The influence of the picture supposes, that we
_believe_ our friend to have once existed. Contiguity to home can never
excite our ideas of home, unless we _believe_ that it really exists. Now
I assert, that this belief, where it reaches beyond the memory or
senses, is of a similar nature, and arises from similar causes, with the
transition of thought and vivacity of conception here explained. When I
throw a piece of dry wood into a fire, my mind is immediately carried to
conceive, that it augments, not extinguishes the flame. This transition
of thought from the cause to the effect proceeds not from reason. It
derives its origin altogether from custom and experience. And as it
first begins from an object, present to the senses, it renders the idea
or conception of flame more strong and lively than any loose, floating
reverie of the imagination. That idea arises immediately. The thought
moves instantly towards it, and conveys to it all that force of
conception, which is derived from the impression present to the senses.
When a sword is levelled at my breast, does not the idea of wound and
pain strike me more strongly, than when a glass of wine is presented to
me, even though by accident this idea should occur after the appearance
of the latter object? But what is there in this whole matter to cause
such a strong conception, except only a present object and a customary
transition to the idea of another object, which we have been accustomed
to conjoin with the former? This is the whole operation of the mind, in
all our conclusions concerning matter of fact and existence; and it is a
satisfaction to find some analogies, by which it may be explained. The
transition from a present object does in all cases give strength and
solidity to the related idea.

Here, then, is a kind of pre-established harmony between the course of
nature and the succession of our ideas; and though the powers and
forces, by which the former is governed, be wholly unknown to us; yet
our thoughts and conceptions have still, we find, gone on in the same
train with the other works of nature. Custom is that principle, by which
this correspondence has been effected; so necessary to the subsistence
of our species, and the regulation of our conduct, in every circumstance
and occurrence of human life. Had not the presence of an object,
instantly excited the idea of those objects, commonly conjoined with it,
all our knowledge must have been limited to the narrow sphere of our
memory and senses; and we should never have been able to adjust means to
ends, or employ our natural powers, either to the producing of good, or
avoiding of evil. Those, who delight in the discovery and contemplation
of _final causes_, have here ample subject to employ their wonder and
admiration.

45. I shall add, for a further confirmation of the foregoing theory,
that, as this operation of the mind, by which we infer like effects from
like causes, and _vice versa_, is so essential to the subsistence of all
human creatures, it is not probable, that it could be trusted to the
fallacious deductions of our reason, which is slow in its operations;
appears not, in any degree, during the first years of infancy; and at
best is, in every age and period of human life, extremely liable to
error and mistake. It is more conformable to the ordinary wisdom of
nature to secure so necessary an act of the mind, by some instinct or
mechanical tendency, which may be infallible in its operations, may
discover itself at the first appearance of life and thought, and may be
independent of all the laboured deductions of the understanding. As
nature has taught us the use of our limbs, without giving us the
knowledge of the muscles and nerves, by which they are actuated; so has
she implanted in us an instinct, which carries forward the thought in a
correspondent course to that which she has established among external
objects; though we are ignorant of those powers and forces, on which
this regular course and succession of objects totally depends.

SECTION VI.

OF PROBABILITY[9].

[9] Mr. Locke divides all arguments into demonstrative and
probable. In this view, we must say, that it is only probable
all men must die, or that the sun will rise to-morrow. But to
conform our language more to common use, we ought to divide
arguments into _demonstrations_, _proofs_, and _probabilities_.
By proofs meaning such arguments from experience as leave no
room for doubt or opposition.

46. Though there be no such thing as _Chance_ in the world; our
ignorance of the real cause of any event has the same influence on the
understanding, and begets a like species of belief or opinion.

There is certainly a probability, which arises from a superiority of
chances on any side; and according as this superiority encreases, and
surpasses the opposite chances, the probability receives a
proportionable encrease, and begets still a higher degree of belief or
assent to that side, in which we discover the superiority. If a dye were
marked with one figure or number of spots on four sides, and with
another figure or number of spots on the two remaining sides, it would
be more probable, that the former would turn up than the latter; though,
if it had a thousand sides marked in the same manner, and only one side
different, the probability would be much higher, and our belief or
expectation of the event more steady and secure. This process of the
thought or reasoning may seem trivial and obvious; but to those who
consider it more narrowly, it may, perhaps, afford matter for curious
speculation.

It seems evident, that, when the mind looks forward to discover the
event, which may result from the throw of such a dye, it considers the
turning up of each particular side as alike probable; and this is the
very nature of chance, to render all the particular events, comprehended
in it, entirely equal. But finding a greater number of sides concur in
the one event than in the other, the mind is carried more frequently to
that event, and meets it oftener, in revolving the various possibilities
or chances, on which the ultimate result depends. This concurrence of
several views in one particular event begets immediately, by an
inexplicable contrivance of nature, the sentiment of belief, and gives
that event the advantage over its antagonist, which is supported by a
smaller number of views, and recurs less frequently to the mind. If we
allow, that belief is nothing but a firmer and stronger conception of an
object than what attends the mere fictions of the imagination, this
operation may, perhaps, in some measure, be accounted for. The
concurrence of these several views or glimpses imprints the idea more
strongly on the imagination; gives it superior force and vigour; renders
its influence on the passions and affections more sensible: and in a
word, begets that reliance or security, which constitutes the nature of
belief and opinion.

47. The case is the same with the probability of causes, as with that of
chance. There are some causes, which are entirely uniform and constant
in producing a particular effect; and no instance has ever yet been
found of any failure or irregularity in their operation. Fire has always
burned, and water suffocated every human creature: The production of
motion by impulse and gravity is an universal law, which has hitherto
admitted of no exception. But there are other causes, which have been
found more irregular and uncertain; nor has rhubarb always proved a
purge, or opium a soporific to every one, who has taken these medicines.
It is true, when any cause fails of producing its usual effect,
philosophers ascribe not this to any irregularity in nature; but
suppose, that some secret causes, in the particular structure of parts,
have prevented the operation. Our reasonings, however, and conclusions
concerning the event are the same as if this principle had no place.
Being determined by custom to transfer the past to the future, in all
our inferences; where the past has been entirely regular and uniform, we
expect the event with the greatest assurance, and leave no room for any
contrary supposition. But where different effects have been found to
follow from causes, which are to _appearance_ exactly similar, all these
various effects must occur to the mind in transferring the past to the
future, and enter into our consideration, when we determine the
probability of the event. Though we give the preference to that which
has been found most usual, and believe that this effect will exist, we
must not overlook the other effects, but must assign to each of them a
particular weight and authority, in proportion as we have found it to be
more or less frequent. It is more probable, in almost every country of
Europe, that there will be frost sometime in January, than that the
weather will continue open throughout that whole month; though this
probability varies according to the different climates, and approaches
to a certainty in the more northern kingdoms. Here then it seems
evident, that, when we transfer the past to the future, in order to
determine the effect, which will result from any cause, we transfer all
the different events, in the same proportion as they have appeared in
the past, and conceive one to have existed a hundred times, for
instance, another ten times, and another once. As a great number of
views do here concur in one event, they fortify and confirm it to the
imagination, beget that sentiment which we call _belief,_ and give its
object the preference above the contrary event, which is not supported
by an equal number of experiments, and recurs not so frequently to the
thought in transferring the past to the future. Let any one try to
account for this operation of the mind upon any of the received systems
of philosophy, and he will be sensible of the difficulty. For my part, I
shall think it sufficient, if the present hints excite the curiosity of
philosophers, and make them sensible how defective all common theories
are in treating of such curious and such sublime subjects.

SECTION VII.

OF THE IDEA OF NECESSARY CONNEXION.

PART I.

48. The great advantage of the mathematical sciences above the moral
consists in this, that the ideas of the former, being sensible, are
always clear and determinate, the smallest distinction between them is
immediately perceptible, and the same terms are still expressive of the
same ideas, without ambiguity or variation. An oval is never mistaken
for a circle, nor an hyperbola for an ellipsis. The isosceles and
scalenum are distinguished by boundaries more exact than vice and
virtue, right and wrong. If any term be defined in geometry, the mind
readily, of itself, substitutes, on all occasions, the definition for
the term defined: Or even when no definition is employed, the object
itself may be presented to the senses, and by that means be steadily and
clearly apprehended. But the finer sentiments of the mind, the
operations of the understanding, the various agitations of the passions,
though really in themselves distinct, easily escape us, when surveyed by
reflection; nor is it in our power to recal the original object, as
often as we have occasion to contemplate it. Ambiguity, by this means,
is gradually introduced into our reasonings: Similar objects are readily
taken to be the same: And the conclusion becomes at last very wide of
the premises.

One may safely, however, affirm, that, if we consider these sciences in
a proper light, their advantages and disadvantages nearly compensate
each other, and reduce both of them to a state of equality. If the mind,
with greater facility, retains the ideas of geometry clear and
determinate, it must carry on a much longer and more intricate chain of
reasoning, and compare ideas much wider of each other, in order to reach
the abstruser truths of that science. And if moral ideas are apt,
without extreme care, to fall into obscurity and confusion, the
inferences are always much shorter in these disquisitions, and the
intermediate steps, which lead to the conclusion, much fewer than in the
sciences which treat of quantity and number. In reality, there is
scarcely a proposition in Euclid so simple, as not to consist of more
parts, than are to be found in any moral reasoning which runs not into
chimera and conceit. Where we trace the principles of the human mind
through a few steps, we may be very well satisfied with our progress;
considering how soon nature throws a bar to all our enquiries concerning
causes, and reduces us to an acknowledgment of our ignorance. The chief
obstacle, therefore, to our improvement in the moral or metaphysical
sciences is the obscurity of the ideas, and ambiguity of the terms. The
principal difficulty in the mathematics is the length of inferences and
compass of thought, requisite to the forming of any conclusion. And,
perhaps, our progress in natural philosophy is chiefly retarded by the
want of proper experiments and phaenomena, which are often discovered by
chance, and cannot always be found, when requisite, even by the most
diligent and prudent enquiry. As moral philosophy seems hitherto to have
received less improvement than either geometry or physics, we may
conclude, that, if there be any difference in this respect among these
sciences, the difficulties, which obstruct the progress of the former,
require superior care and capacity to be surmounted.

49. There are no ideas, which occur in metaphysics, more obscure and
uncertain, than those of _power, force, energy_ or _necessary
connexion_, of which it is every moment necessary for us to treat in all
our disquisitions. We shall, therefore, endeavour, in this section, to
fix, if possible, the precise meaning of these terms, and thereby remove
some part of that obscurity, which is so much complained of in this
species of philosophy.

It seems a proposition, which will not admit of much dispute, that all
our ideas are nothing but copies of our impressions, or, in other words,
that it is impossible for us to _think_ of any thing, which we have not
antecedently _felt_, either by our external or internal senses. I have
endeavoured[10] to explain and prove this proposition, and have expressed
my hopes, that, by a proper application of it, men may reach a greater
clearness and precision in philosophical reasonings, than what they have
hitherto been able to attain. Complex ideas may, perhaps, be well known
by definition, which is nothing but an enumeration of those parts or
simple ideas, that compose them. But when we have pushed up definitions
to the most simple ideas, and find still some ambiguity and obscurity;
what resource are we then possessed of? By what invention can we throw
light upon these ideas, and render them altogether precise and
determinate to our intellectual view? Produce the impressions or
original sentiments, from which the ideas are copied. These impressions
are all strong and sensible. They admit not of ambiguity. They are not
only placed in a full light themselves, but may throw light on their
correspondent ideas, which lie in obscurity. And by this means, we may,
perhaps, attain a new microscope or species of optics, by which, in the
moral sciences, the most minute, and most simple ideas may be so
enlarged as to fall readily under our apprehension, and be equally known
with the grossest and most sensible ideas, that can be the object of
our enquiry.

[10] Section II.

50. To be fully acquainted, therefore, with the idea of power or
necessary connexion, let us examine its impression; and in order to find
the impression with greater certainty, let us search for it in all the
sources, from which it may possibly be derived.

When we look about us towards external objects, and consider the
operation of causes, we are never able, in a single instance, to
discover any power or necessary connexion; any quality, which binds the
effect to the cause, and renders the one an infallible consequence of
the other. We only find, that the one does actually, in fact, follow the
other. The impulse of one billiard-ball is attended with motion in the
second. This is the whole that appears to the _outward_ senses. The mind
feels no sentiment or _inward_ impression from this succession of
objects; Consequently, there is not, in any single, particular instance
of cause and effect, any thing which can suggest the idea of power or
necessary connexion.

From the first appearance of an object, we never can conjecture what
effect will result from it. But were the power or energy of any cause
discoverable by the mind, we could foresee the effect, even without
experience; and might, at first, pronounce with certainty concerning it,
by mere dint of thought and reasoning.

In reality, there is no part of matter, that does ever, by its sensible
qualities, discover any power or energy, or give us ground to imagine,
that it could produce any thing, or be followed by any other object,
which we could denominate its effect. Solidity, extension, motion; these
qualities are all complete in themselves, and never point out any other
event which may result from them. The scenes of the universe are
continually shifting, and one object follows another in an uninterrupted
succession; but the power of force, which actuates the whole machine, is
entirely concealed from us, and never discovers itself in any of the
sensible qualities of body. We know, that, in fact, heat is a constant
attendant of flame; but what is the connexion between them, we have no
room so much as to conjecture or imagine. It is impossible, therefore,
that the idea of power can be derived from the contemplation of bodies,
in single instances of their operation; because no bodies ever discover
any power, which can be the original of this idea.[11]

[11] Mr. Locke, in his chapter of power, says that, finding
from experience, that there are several new productions in
nature, and concluding that there must somewhere be a power
capable of producing them, we arrive at last by this reasoning
at the idea of power. But no reasoning can ever give us a new,
original, simple idea; as this philosopher himself confesses.
This, therefore, can never be the origin of that idea.

51. Since, therefore, external objects as they appear to the senses,
give us no idea of power or necessary connexion, by their operation in
particular instances, let us see, whether this idea be derived from
reflection on the operations of our own minds, and be copied from any
internal impression. It may be said, that we are every moment conscious
of internal power; while we feel, that, by the simple command of our
will, we can move the organs of our body, or direct the faculties of our
mind. An act of volition produces motion in our limbs, or raises a new
idea in our imagination. This influence of the will we know by
consciousness. Hence we acquire the idea of power or energy; and are
certain, that we ourselves and all other intelligent beings are
possessed of power. This idea, then, is an idea of reflection, since it
arises from reflecting on the operations of our own mind, and on the
command which is exercised by will, both over the organs of the body and
faculties of the soul.

52. We shall proceed to examine this pretension; and first with regard
to the influence of volition over the organs of the body. This
influence, we may observe, is a fact, which, like all other natural
events, can be known only by experience, and can never be foreseen from
any apparent energy or power in the cause, which connects it with the
effect, and renders the one an infallible consequence of the other. The
motion of our body follows upon the command of our will. Of this we are
every moment conscious. But the means, by which this is effected; the
energy, by which the will performs so extraordinary an operation; of
this we are so far from being immediately conscious, that it must for
ever escape our most diligent enquiry.

For _first_; is there any principle in all nature more mysterious than
the union of soul with body; by which a supposed spiritual substance
acquires such an influence over a material one, that the most refined
thought is able to actuate the grossest matter? Were we empowered, by a
secret wish, to remove mountains, or control the planets in their orbit;
this extensive authority would not be more extraordinary, nor more
beyond our comprehension. But if by consciousness we perceived any power
or energy in the will, we must know this power; we must know its
connexion with the effect; we must know the secret union of soul and
body, and the nature of both these substances; by which the one is able
to operate, in so many instances, upon the other.

_Secondly_, We are not able to move all the organs of the body with a
like authority; though we cannot assign any reason besides experience,
for so remarkable a difference between one and the other. Why has the
will an influence over the tongue and fingers, not over the heart or
liver? This question would never embarrass us, were we conscious of a
power in the former case, not in the latter. We should then perceive,
independent of experience, why the authority of will over the organs of
the body is circumscribed within such particular limits. Being in that
case fully acquainted with the power or force, by which it operates, we
should also know, why its influence reaches precisely to such
boundaries, and no farther.

A man, suddenly struck with palsy in the leg or arm, or who had newly
lost those members, frequently endeavours, at first to move them, and
employ them in their usual offices. Here he is as much conscious of
power to command such limbs, as a man in perfect health is conscious of
power to actuate any member which remains in its natural state and
condition. But consciousness never deceives. Consequently, neither in
the one case nor in the other, are we ever conscious of any power. We
learn the influence of our will from experience alone. And experience
only teaches us, how one event constantly follows another; without
instructing us in the secret connexion, which binds them together, and
renders them inseparable.

_Thirdly,_ We learn from anatomy, that the immediate object of power in
voluntary motion, is not the member itself which is moved, but certain
muscles, and nerves, and animal spirits, and, perhaps, something still
more minute and more unknown, through which the motion is successively
propagated, ere it reach the member itself whose motion is the immediate
object of volition. Can there be a more certain proof, that the power,
by which this whole operation is performed, so far from being directly
and fully known by an inward sentiment or consciousness, is, to the last
degree mysterious and unintelligible? Here the mind wills a certain
event: Immediately another event, unknown to ourselves, and totally
different from the one intended, is produced: This event produces
another, equally unknown: Till at last, through a long succession, the
desired event is produced. But if the original power were felt, it must
be known: Were it known, its effect also must be known; since all power
is relative to its effect. And _vice versa,_ if the effect be not known,
the power cannot be known nor felt. How indeed can we be conscious of a
power to move our limbs, when we have no such power; but only that to
move certain animal spirits, which, though they produce at last the
motion of our limbs, yet operate in such a manner as is wholly beyond
our comprehension?

We may, therefore, conclude from the whole, I hope, without any
temerity, though with assurance; that our idea of power is not copied
from any sentiment or consciousness of power within ourselves, when we
give rise to animal motion, or apply our limbs to their proper use and
office. That their motion follows the command of the will is a matter of
common experience, like other natural events: But the power or energy by
which this is effected, like that in other natural events, is unknown
and inconceivable.[12]

[12] It may be pretended, that the resistance which we meet
with in bodies, obliging us frequently to exert our force, and
call up all our power, this gives us the idea of force and
power. It is this _nisus_, or strong endeavour, of which we are
conscious, that is the original impression from which this idea
is copied. But, first, we attribute power to a vast number of
objects, where we never can suppose this resistance or exertion
of force to take place; to the Supreme Being, who never meets
with any resistance; to the mind in its command over its ideas
and limbs, in common thinking and motion, where the effect
follows immediately upon the will, without any exertion or

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