An Enquiry
Concerning
Human Understanding
David Hume
Contents
Sect. I. Of the different Species of Philosophy ................................... 5
Sect. II. Of the Origin of Ideas ......................................................... 13
Sect. III. Of the Association of Ideas ............................................... 17
Sect. IV. Sceptical Doubts concerning the Operations of the Understanding ..................................................................................... 18
Sect. V. Sceptical Solution of these Doubts ..................................... 29
Sect. VI. Of Probability9 ................................................................. 40
Sect. VII. Of the Idea of necessary Connexion ................................ 42
Sect. VIII. Of Liberty and Necessity ................................................ 55
Sect. IX. Of the Reason of Animals ................................................. 72
Sect. X. Of Miracles ........................................................................ 75
Sect. XI. Of a particular Providence and of a future State .............. 91
Sect. XII. Of the academical or sceptical Philosophy .................... 103
Notes ............................................................................................... 114
Sect. 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 considers man in the light of a
reasonable rather than an active being, and endeavours 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
6/David Hume
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
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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 anything 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
8/David Hume
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
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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 the 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. Chased 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
10/David Hume
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 dis-
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criminate 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
12/David Hume
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
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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!
Sect. 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
14/David Hume
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
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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 sensa-
16/David Hume
tion.
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
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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
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.
Sect. 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,
18/David Hume
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.
Sect. 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.
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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 tomorrow 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 realtion 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
20/David Hume
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
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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 billiardball 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;
22/David Hume
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.
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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
24/David Hume
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 powers6 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
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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.
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 fact 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
26/David Hume
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 a 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
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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 resem-
28/David Hume
blance 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
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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.
Sect. 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
30/David Hume
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
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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
32/David Hume
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 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 con-
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duct, 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.
34/David Hume
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 objectsflame 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
further; 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,
Enquiry Concerning Human Understanding/35
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 billiardball 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,
36/David Hume
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
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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
38/David Hume
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 anything 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
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 ap-
Enquiry Concerning Human Understanding/39
peared 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. Continguity 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
40/David Hume
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.
Sect. VI. Of Probability9
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 die 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
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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 die, it considers the
turning up of each particular side as alike probable; and this 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 alwa...
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