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• An Enquiry Concerning Human Understanding
• Section I.: Of the Different Species of Philosophy.
• Section II.: Of the Origin of Ideas.
• Section III.: Of the Association of Ideas.
• Section IV.: Sceptical Doubts Concerning the Operations of the Understanding.
• Section V.: Sceptical Solution of These Doubts.
• Section VI.: Of Probability1 .
• Section VII.: Of the Idea of Necessary Connexion.
• Section VIII.: Of Liberty and Necessity.
• Section IX.: Of the Reason of Animals.
• Section X.: Of Miracles.
• Section XI.: Of a Particular Providence and of a Future State.
• Section XII.: Of the Academical Or Sceptical Philosophy.
• An Enquiry Concerning the Principles of Morals
• Section I.: Of the General Principles of Morals.
• Section II.: Of Benevolence
• Section III.: Of Justice.
• Section IV.: Of Political Society.
• Section V.: Why Utility Pleases.
• Section VI.: Of Qualities Useful to Ourselves.
• Section VII.: Of Qualities Immediately Agreeable to Ourselves.
• Section VIII.: Of Qualities Immediately Agreeable to Others1 .
• Section IX.: Conclusion.
• Appendix I. Concerning Moral Sentiment.
• Appendix II. Of Self-love.
• Appendix III. Some Farther Considerations With Regard to Justice.
• Appendix IV. Of Some Verbal Disputes.
• A Dialogue.
• Additional Note to P. 125, L. 4.

NOTE TO THE FIRST EDITION

This edition is a reprint of the second volume of the posthumous edition of 1777, omitting ‘A Dissertation on the Passions,’ ‘A Dialogue,’ ‘The Natural History of Religion,’ and a long note (L) to § x. Of Miracles, in the ‘Enquiry concerning Human Understanding.’

The marginal sections have been introduced merely for convenience of reference, and for the clearer articulation of the argument, and do not correspond to anything in the original edition.

Three comparative tables of contents are given at the end of the Introduction, showing the relation of the two Enquiries and the Dissertation on the Passion to the three books of the Treatise.

In these tables, and also in the Index and Introduction, the references to the Enquiries are made by means of the marginal sections of the present edition, those to the Dissertation by means of the pages of the edition of 1777, and those to the Treatise by means of the pages of the Clarendon Press edition, Oxford, 1888.

NOTE TO THE SECOND EDITION

This edition contains ‘A Dialogue’ and the note to § x which were omitted in the first edition.

EDITOR’S INTRODUCTION

Hume’s philosophic writings are to be read with great caution. His pages, especially those of the Treatise, are so full of matter, he says so many different things in so many different ways and different connexions, and with so much indifference to what he has said before, that it is very hard to say positively that he taught, or did not teach, this or that particular doctrine. He applies the same principles to such a great variety of subjects that it is not surprising that many verbal, and some real inconsistencies can be found in his statements. He is ambitious rather than shy of saying the same thing in different ways, and at the same time he is often slovenly and indifferent about his words and formulae. This makes it easy to find all philosophies in Hume, or, by setting up one statement against another, none at all. Of Professor Green’s criticism of Hume it is impossible to speak, here in Oxford, without the greatest respect. Apart from its philosophic importance, it is always serious and legitimate; but it is also impossible not to feel that it would have been quite as important and a good deal shorter, if it had contained fewer of the verbal victories which are so easily won over Hume.

The question whether Hume’s philosophy is to be judged by his Treatise or his Enquiries is of some interest, and this Introduction aims chiefly at making clear the relation between them.

Hume composed his Treatise between the ages of twenty-one and twenty-five, finishing it in the year 1736. The first two books were published in 1739, and the third book in 1740. The first edition of the Enquiry into the Human Understanding appeared in 1748; the Enquiry concerning the Principles of Morals appeared in 1751, and the Dissertation on the Passions (corresponding to Bk. II of the Treatise) in 17571 .

Hume says himself that the Treatise ‘fell dead-born from the press without reaching such distinction as even to excite a murmur among the zealots.’ That distinction was, to the end of his life, particularly dear to Hume, and it will be seen that in the Enquiries he made a bold bid for it in his quite superfluous section on Miracles and a Particular Providence. He entertained the notion, however, that his want of success in publishing the Treatise ‘had proceeded more from the manner than the matter,’ and that he had been ‘guilty of a very usual indiscretion in going to the press too early.’ He therefore ‘cast the first part of that work anew in the Enquiry concerning the Human Understanding,’ and afterwards continued the same process in his Enquiry concerning the Principles of Morals, which, he says, ‘in my own opinion is of all my writings, historical, philosophical, or literary, incomparably the best.’ In the posthumous edition of his Collected Essays of 1777, the Advertisement, on which so much stress has been laid, first appeared. It is printed at the beginning of this reprint, and declares the author’s desire that ‘the following pieces may alone be regarded as containing his philosophical sentiments and principles.’

This declaration has not only been taken seriously by some writers, but they have even complied with it and duly ignored the Treatise. By others it has been treated as an interesting indication of the character of a man who had long ago given up philosophy, who always had a passion for applause, and little respect or generosity for his own failures. By Mr. Grose the Advertisement is regarded as ‘the posthumous utterance of a splenetic invalid,’ and Mr. Green’s elaborate criticism is directed almost entirely against the Treatise.

To discuss a question of literary justice would be out of place in an Introduction which aims at estimating philosophic importance. Two remarks, however, may be made before passing on.

The first is, that even in Hume’s philosophical writings the author’s personal character continually excites our interest. The Treatise, as was noticed at the time of its publication, is full of egoisms. Even in this severe work, together with a genuine ardour and enthusiasm, there is an occasional note of insincerity, arrogance or wantonness which strikes the serious student painfully. The following pages will perhaps show that Hume, in re-casting the Treatise into its new form, displayed the less admirable sides of his temper rather freely.

In the second place, it is undeniable that Hume’s own judgement on the style of his earlier work was quite correct. The Treatise was ill-proportioned, incoherent, ill-expressed. There are ambiguities and obscurities of expression in important passages which are most exasperating. Instead of the easy language, familiar and yet precise, of the Enquiries, we have an amount of verbal vagueness and slovenliness for which it is hard to excuse even ‘a solitary Scotchman.’ How far the difference between the two works is merely one of style is considered below, but whether it be due to matter or manner, it remains that the Enquiries are an easy book and the Treatise a very hard one. In the Treatise he revels in minutiae, in difficulties, in paradoxes: he heaps questions upon himself, and complicates argument by argument: he is pedantic and captious. In the Enquiry he ignores much with which he had formerly vexed his own and his readers’ souls, and like a man of the world takes the line of least resistance (except as touching the ‘zealots’). He gives us elegance, lucidity and proportion.

Perhaps it may be allowed the writer here to record his own adherence to those who judge Hume’s philosophy by his Treatise. Bk. I of the Treatise is beyond doubt a work of first-rate philosophic importance, and in some ways the most important work of philosophy in the English language. It would be impossible to say the same of the Enquiries, and although in one sense the Enquiry concerning the Principles of Morals is the best thing Hume ever wrote, to ignore the Treatise is to deprive him of his place among the great thinkers of Europe.

At the same time it is perhaps well worth while to examine rather closely the actual relations between the contents of the earlier and later works. The comparative tables of contents which are printed at the end of this Introduction may perhaps save the student some ungrateful labour, and show, in a graphic form, at all events the relative amount of space assigned to various subjects in the two works. The difference in the method of treatment, conclusions, and general tone can of course only be gathered by reading the different passages side by side. The results of such a reading are presented in the following pages.

Taking the Enquiry concerning the Human Understanding separately, we are at once struck by the entire omission of Bk. I, part ii of the Treatise. Space and time are not treated of at all in the Enquiry as independent subjects interesting in themselves; they are only introduced incidentally in §§ 124–5 of the Enquiry, as illustrating the absurdity of the abstract sciences and in support of a sceptical position.

We are also struck by the introduction of the two theological sections (x-xi) of the Enquiry, and by the very small space given to the general questions concerning knowledge and the relation of subject and object.

Sections 116–132, covering only seventeen pages in all, do duty in the Enquiry for the whole of Bk. I, part iv of the Treatise, where ninety-four pages are devoted to the same topics.

This wholesale omission and insertion cannot well be due to philosophical discontent with the positions or arguments, or to a general desire to fill up a gap in the system, but must be ascribed rather to a general desire to make the Enquiry readable. Parts ii and iv are certainly the hardest in the Treatise, and the least generally interesting to the habitués of coffee-houses, especially at a period when ‘the greatest part of men have agreed to convert reading into an amusement;’ whereas a lively and sceptical discussion of miracles and providence could hardly fail to find readers, attract attention, and excite that ‘murmur among the zealots’ by which the author desired to be distinguished.

Taking the two works rather more in detail, we find these notable differences:—

Psychology. Even in the Treatise we feel that the introductory psychology is rather meagre and short to serve as a foundation for so large a system, but in the Enquiry it is still more cut down.

Thus the Enquiry omits the distinction between simple and complex ideas; between impressions of sensation and reflexion, which is of importance afterwards for the explanation of the idea of necessary connexion; between ideas of memory and imagination: in the treatment of association little is said about causation as a principle of association, and the account of the products of association, the three classes of complex ideas, relations, modes and substances, and abstract ideas, disappears.

Thus the list of philosophic relations and the distinction between philosophic and natural relation are omitted, and do not appear at all in the Enquiry. The question of abstraction is only alluded to incidentally near the end of the Enquiry (§§ 122 and 125 n). Substance is passed over, as it is also in § xii of the Enquiry, probably both from the difficulty of the subject, and because in the Enquiry Hume is not nearly so anxious to show that the fundamental popular conceptions are fictitious. There is something solid to which the popular conception of causation can be reduced, but when substance and body are analyzed, as they are in the Treatise, the importance of the materials out of which they are said to be formed is out of all proportion to the place which the finished products occupy in thought and language.

The slight treatment of association again is quite characteristic of the temper of the Enquiry. The details of psychical mechanism, which are rather tiresomely paraded in the Treatise, are consistently passed over in the Enquiry, notably so in the case of sympathy.

Space and Time. It must be admitted that the subject of space and time, as treated in the Treatise, is not very attractive. There is nothing in the Enquiry corresponding to the forty-two pages of the Treatise, in which space and time are treated, except two pages in § xii.

Of the philosophical importance of Hume’s treatment of them in the Treatise it is unnecessary to speak; it is apparent from the large amount of criticism which Professor Green thought fit to bestow on it. It is to be noted, however, that the account of causation which Hume gives afterwards in the Enquiry, is left hanging in the air when the support of the theory of succession has been withdrawn. The omission of the section on the ideas of existence and external existence is, like the omission of the various accounts of substance, only a part of Hume’s avoidance of the general question of the relation of knowledge and reality.

Causation. In the account of causation Hume passes over the very interesting and fundamental question raised in the Treatise of the position of cause in the fabric of our knowledge. On p. 78 of the Treatise (Bk. I, iii, § 3; cf. p. 157), he asks why a cause is always necessary, and concludes that there is no reason for the presumption that everything must have a cause. This conclusion he supports by his analysis of the idea of a particular cause, and asserts again (p. 172) that there is ‘no absolute metaphysical necessity’ that one object should have another associated with it in such a way that its idea shall determine the mind to form the idea of the other. This conclusion is of the gravest importance for Hume’s theory of causation in general, and is difficult to reconcile with his negation of the reality of chance and his assumption of secret causes (Treatise, pp. 130, 132). His failure in the Enquiry to take the opportunity of treating this question over again is significant of the lower philosophic standard of the later work, especially as he does take the opportunity to add a good deal to his previous discussion of the origin of the idea of power (Enquiry, §§ 51–3, 60 n; cf. Treatise, p. 632, Appendix). In the same spirit the distinction between essential and accidental circumstances, and the question of the employment of general rules (Treatise, pp. 145f, 173f), subjects of great speculative as well as practical interest, are ignored in the Enquiry.

A good deal of psychological detail is omitted in the Enquiry. Thus §§ v, ix, x and xiii of Bk. I, part iii, of the Treatise are omitted bodily, partly no doubt to shorten the discussion, and partly on Hume’s new principle of not trying to penetrate beneath the obvious explanations of phenomena. He adds, however, a detailed discussion (Enquiry, §§ 51–3) of the possibility of deriving the idea of power from an internal impression, such as the feeling of initiative or effort accompanying a bodily or mental movement. These sections would appear to be occasioned by contemporary discussions, and are excellently expressed. On the same footing stands the discussion of the theory of occasional causes, which is very well done in §§ 54–7 of the Enquiry (cf. Treatise, p. 171). The omission of the practical § xv of the Treatise, on the rules by which to judge of causes and effects, appears rather strange, unless we regard it as raising a difficult general question which Hume has already shown his anxiety to avoid in his omission of § iii. With regard to the account of the origin, in particular cases, of the idea of cause and effect, there is little difference between the Treatise and Enquiry, except that in the Enquiry ‘contiguity’ practically drops out altogether. A good deal was said about contiguity in § ix of the Treatise, which disappears in the Enquiry; and again in the final definitions of cause given in § xiv, pp. 170–172 of the Treatise, contiguity appears on the same level as resemblance, whereas in the definitions given in the Enquiry, § 60, no mention is made of it at all.

A comparison of the definitions given on pp. 170–2 of the Treatise and § 60 of the Enquiry, shows that in the Enquiry the distinction between causation as a philosophical and a natural relation is altogether dropped. In the Treatise this distinction is very hard to follow, and there is little doubt that the sacrifice of it in the Enquiry is deliberate. In the Enquiry Hume asserts more clearly than in the Treatise (though with some of the old inconsistencies) that there is nothing at the bottom of causation except a mental habit of transition or expectation, or, in other words, a ‘natural relation.’ Thus the omission of the chapter on the rules by which to judge of cause and effect and the sacrifice of contiguity are both part of the same policy: succession cannot be got rid of altogether, and this, it is true, is a philosophical relation (Treatise, p. 14), but it is one which is a matter of perception rather than reasoning (Treatise, p. 73), and is not one which raises much discussion—we seldom have much difficulty in discovering whether A or B came first, and you cannot strictly say that B was more consequent on A than C was, or vice versa. But men of science are very curious about contiguity, and the examination of it as a philosophical relation would often run counter to the connexions established by contiguity as a natural relation. Contiguity therefore drops out of the Enquiry as a philosophical relation, though it must be supposed to exert its influence as a natural relation (cf. Treatise, p. 92).

Resemblance was not treated in the Treatise as a philosophical relation, in connexion with causation, but rather as a natural relation, i. e. not as a relation between A and B which men of science would take into consideration, but as the relation between a¹ b¹, a² b², a³ b³, &c., which was the foundation of the unconscious habit of proceeding to assert a⁴ b⁴ or A B. This position is still more clearly given to resemblance in the Enquiry, where Hume asserts roundly that one instance is as good philosophically (or as we should say, ‘scientifically’) as a thousand (cf. Enquiry, § 31). The only effect of resemblance or repetition is to produce a habit.

Philosophical relations are those which a man of science perceives or establishes when he consciously compares one object with another. Natural relations are those which unconsciously join one idea to another in his mind. In the case of causation, therefore, a philosophical relation must be between A and B, a¹ and b¹, a² and b²: natural relation must be between one particular case of A B and another, e. g. between a¹ b¹ and a² b², a³ b³, &c. The philosophical relation of causation is what a man of science sees in one case of A B taken by itself, and that is nothing but succession and contiguity. Hume feeling the difficulty of maintaining philosophical relations at all, wisely says nothing in the Enquiry about their difference from natural relations, and says as little as possible about those elements of causation which he cannot spare, and which in the Treatise appeared as philosophical relations. The distinction in the Treatise is indeed most bewildering, but, with its disappearance in the Enquiry, the relation of causation becomes more completely subjective, and it becomes even more hard than in the Treatise to see how there can be any difference between real and apparent causes, or any room for concealed causes. On the other hand, it may be said that, so long as natural was opposed to philosophical relation, there was still possible an invidious contrast between the subjectivity of the one and the objectivity of the other, while in the Enquiry some credit is restored to causation, because nothing is said about its seven philosophical rivals. Both in the Enquiry and Treatise the operations of resemblance, contiguity and succession, are described in language which is far from precise and clear, and which justifies many of the lively strictures passed on the association theory by Mr. Bradley in his Principles of Logic; but it is certainly easier to grasp Hume’s meaning in the Enquiry than in the Treatise, and a comparison of the passages containing the definitions is decidedly instructive.

It will be noted that in the Enquiry, § 60, Hume interjects a curious little explanation of his first definition: ‘We may define a cause to be an object followed by another, and when all the objects similar to the first are followed by objects similar to the second, or, in other words, where if the first object had not been, the second never had existed.’ The words in italics can hardly be regarded as a paraphrase or equivalent of the main definition, and must be added to the rather large collection of unassimilated dicta which so much occupied Professor Green.

Liberty and necessity.—Hume has certainly effected an improvement in the Enquiry by bringing this subject into closer connexion with his theory of causation. In the Treatise he deals with it under the general heading of the ‘will and direct passions,’ and with an interval of more than 200 pages from the main treatment of cause. The only important differences between the two discussions of the freedom of the will are (a) the omission in the Enquiry of the preliminary definition of the will (Treatise, p. 399), (b) the insertion in the Enquiry of the definition of ‘liberty,’ § 73, (c) the more emphatic assertion in the Enquiry that the whole dispute is one of words, and that all men have really been always agreed on the matter. (Cf. Enquiry, §§ 62–3, 71, 73, and Treatise, pp. 399, 407, 409.) (d) The development of the religious aspect of the question, Enquiry, §§ 76–81. To this nothing corresponds in the Treatise, and like the following sections in the Enquiry it may be ascribed to Hume’s ambition to disturb ‘the zealots’ at all costs.

The discussion has been carefully re-written in the Enquiry, many of the illustrations used are different and more elegant, and the whole section in the Enquiry is an excellent instance of the general improvement in style and construction which appears in the later work.

Miracles, providence, and a future state. §§ x and xi of the Enquiry, in which these subjects are treated, belong to Hume’s applied philosophy, and, important and interesting as they are in themselves, they do not add anything to his general speculative position. Their insertion in the Enquiry is due doubtless rather to other considerations than to a simple desire to illustrate or draw corollaries from the philosophical principles laid down in the original work.

Knowledge and reality. § 12 of the Enquiry very inadequately represents the whole of Book I, part iv of the Treatise, occupying as it does only seventeen pages as against ninety-four in the earlier work. In details the correspondence is necessarily very imperfect.

Brevity is, it is true, legitimately attained in some cases by compression. Thus the rather rambling general discussions of Scepticism in the Treatise contained in § i and § vii (some eighteen pages) are fairly represented by § 116 and §§ 126–132 of the Enquiry (some nine pages). So also there is not much reason to complain of the abbreviation to one page of the criticism of the distinction between primary and secondary qualities (Treatise, § iv, pp. 225–231; Enquiry, § 122, pp. 154–5), this part of the Treatise being undeniably cumbrous. Two pages more in the Enquiry are occupied with an illustration of the absurdity of the abstract sciences, drawn from their doctrine of infinite divisibility, this having originally appeared in Book I, p. ii, § ii of the Treatise.

This leaves only §§ 117–121 and 123 of the Enquiry (about four pages) to do duty for the whole of §§ ii, iii, v, vi of the Treatise (some sixty-nine pages).

In the Enquiry Hume merely confines himself to asserting the opposition between the vulgar belief, based on instinct and natural propensity, in external objects on the one side, and the conclusions of philosophy, that we know nothing but perceptions in the mind, on the other side. He does not attempt any further investigation beyond rejecting an appeal to the veracity of God which was not mentioned in the Treatise (Enquiry, § 120), but simply falls back on the position that sceptical arguments, if they admit of no answer, at all events produce no conviction. Perhaps the most interesting part of the whole Treatise is that in which Hume tried to explain (§ ii, pp. 187–218) our belief in the existence of body, which he reduced to the continued and distinct existence of perceptions, by the influence of their constancy and coherence on our imagination. This is entirely dropped in the Enquiry, together with the account of our idea of substance (Treatise, § iii, ‘Of the antient philosophy’), and of our idea of mind (Treatise, § vi, ‘Of personal identity’). A considerable part of the discussion on the immateriality of the soul (Treatise, § v), may appear to us antiquated, just as it may fairly have appeared to Hume too dry for a popular work, and not absolutely necessary to his system. But it is not too much to say on the whole, that the omissions in § 12 of the Enquiry are alone amply sufficient to render it quite impossible to comply with Hume’s wish and treat the Enquiry as representing the whole of his philosophic system.

The Dissertation on the Passions, first published in 1757, together with the Natural History of Religion and two essays on tragedy and taste, and printed in the edition of 1777 between the two Enquiries, is not reprinted in this volume.

It consists largely, as Mr. Grose says, of verbatim extracts from Bk. II of the Treatise, with some trifling verbal alterations.

As it stands, the Dissertation is a very uninteresting and unsatisfactory work. The portion of Bk. II of the Treatise which was perhaps of most general interest, namely the discussion of Liberty and Necessity, had been previously transferred to the Enquiry into Human Understanding, and so was no longer available for the Dissertation. But the Dissertation suffers, not only by this transference of matter, but also by omissions of other really important matters.

(1) In the Treatise an elaborate account was given of pride and humility, love and hatred, and an attempt was made to explain the mechanism of the passions, by the relation of impressions and ideas, which was at all events a serious essay towards something less superficial than the prevalent psychology. Its bearing on Hume’s general system is, it is true, not very great and not at all clear, and it is easy to understand how, as a matter of literary policy, it was omitted by Hume. But in connexion with other omissions it has a decided philosophical significance.

(2) The psychology of sympathy, which occupies so much space in Bk. II, and on which so much depends in Bk. III of the Treatise, is almost entirely ignored in the Enquiry. How it is possible to find room for sympathy in so atomistic or individualistic a psychology as Hume’s, is one of the most interesting questions which are raised by his system. How I can not only know but enter into the feelings of another person, when I can only know my own feelings, is indeed a problem worthy of grave consideration. When we come to consider the treatment of sympathy in the Enquiry concerning the Principles of Morals by the side of its treatment in the Treatise, we shall see reason to think that Hume has very considerably modified his views, not only as to the functions of sympathy, but also as to the proper limits of psychological analysis.

(3) The discussion in the Treatise, Bk. II, § iii, of the relation of passion to reason is of great importance for the subsequent question of the source of moral distinctions, as also are the distinction between calm and violent passions and the identification of reason with the former; but the Dissertation is contented with the barest mention of them.

In general, we may say that, whereas Bk. II of the Treatise was not only valuable as an independent essay in psychology, and interesting from its wealth of observation and illustration, but also important from its preliminary treatment of questions which were going to be of vital importance in Bk. III, the Dissertation is neither interesting in itself nor of any assistance for the interpretation or criticism of the Enquiry concerning the Principles of Morals. The extent of its correspondence with Bk. II of the Treatise is shown in the accompanying comparative Table of Contents.

Enquiry concerning the Principles of Morals. Hume has recorded his own opinion that the Enquiry concerning the Principles of Morals was, of all his writings, ‘historical, philosophical, or literary, incomparably the best.’ It was first published in 1751, the corresponding book in the Treatise having been published in 1740. Hume himself considered that the failure of the Treatise ‘had proceeded more from the manner than the matter,’ and in this Enquiry it is evident that he has given the greatest attention to the style, and with such success as to justify Mr. Grose’s estimate of him as ‘the one master of philosophic English.’

It is far less easy to compare the matter of this Enquiry with that of Bk. III of the Treatise, because the earlier work has, in this case, been really re-written. The comparative Table of Contents will show in a graphic form the difficulty of making out a correspondence between them. The arrangement is largely different. The omissions are not in this case so important as the additions, and there is a great change in the proportions and emphasis with which various subjects are treated. There is also, the writer ventures to believe, a very remarkable change of tone or temper, which, even more than particular statements, leads him to suppose that the system of Morals in the Enquiry is really and essentially different from that in the Treatise.

In the Treatise nothing is more clear than his intention to reduce the various principles of human nature, which appear distinct to ordinary men, to some more general and underlying principle, and indeed his philosophy differed from that of the moral sense school, represented by Hutcheson, in precisely that particular. In other words, he attempted a philosophical explanation of human nature, and was not content to accept the ordinary distinctions of ‘faculties’ and ‘senses’ as final. Thus the temper of the Treatise is well expressed by his emphatic declaration (Bk. III, part iii, § i, p. 578), that it is ‘an inviolable maxim in philosophy, that where any particular cause is sufficient for an effect, we ought to rest satisfied with it, and ought not to multiply causes without necessity’; and again (Bk. II, part i, § iii, p. 282), ‘we find in the course of nature that though the effects be many, the principles from which they arise are commonly but few and simple, and that it is the sign of an unskilful naturalist to have recourse to a different quality in order to explain every different operation. How much more must this be true with regard to the human mind?’ (Cf. also Treatise, Bk. III, part iii, § ii, p. 473.)

With these passages we may compare, observing the caution inculcated at the beginning of this Introduction, § 250 of the Enquiry, where speaking of self-love, he says, ‘The obvious appearance of things . . . must be admitted till some hypothesis be discovered which, by penetrating deeper into human nature, may prove the former affections to be nothing but modifications of the latter. All attempts of this kind have hitherto proved fruitless, and seem to have proceeded entirely from that love of simplicity which has been the source of so much false reasoning in philosophy.’ (Cf. § 9, ‘Philosophers have sometimes carried the matter too far by their passion for some one general principle.’)

Without laying undue stress on these express statements (which go for less in Hume than in most authors), we can hardly help feeling that Hume is approximating to the position of Hutcheson, as expressed in his Preface to the Essay on the Nature and Conduct of the Passions (p. ix, ed. 3, Lond. 1742): ‘Some strange love of simplicity in the structure of human nature . . . has engaged many writers to pass over a great many simple Perceptions which we may find in ourselves: . . . had they . . . considered our affections without a previous notion that they were all from self-love, they might have felt an ultimate desire of the happiness of others as easily conceivable and as certainly implanted in the human breast, though perhaps not so strong as self-love.’ (Cf. ib. p. xiv: ‘This difficulty probably arises from our previous notions of a small number of senses, so that we are unwilling to have recourse in our theories to any more; and rather strain out some explication of Moral Ideas, with relation to some of the natural Powers of Perception universally acknowledged.’)

This change of attitude is, I think, seen in several points, some of which have been already pointed out in dealing with the Dissertation on the Passions, and which are here only distinguished for convenience of reference.

Benevolence. In the Treatise there are passages, it is true, which seem to admit an original unaccountable instinct of benevolence (Treatise, Bk. II, part iii, § iii, p. 417; ib. § ix, p. 439; Bk. II, part ii, § vi, p. 368; cf. Bk. III, part ii, § i, p. 478). There are also passages which sternly limit its extent and influence. Thus he says (Treatise, Bk. III, part ii, § i, p. 481), ‘In general it may be affirmed that there is no such passion in human minds as the love of mankind merely as such, independent of personal qualities, of services, or of relation to oneself. It is true there is no human and indeed no sensible creature whose happiness does not, in some measure, affect us, when brought near to us and represented in lively colours. But this proceeds merely from sympathy, and is no proof of such an universal affection to mankind, since this concern extends itself beyond our own species.’ (Cf. Bk. III, part ii, § ii, p. 496.) With this we may compare the Enquiry, § 184, where he speaks of ‘our natural philanthropy’; § 135, ‘a feeling for the happiness of mankind and a resentment of their misery’; § 252, ‘these and a thousand other instances are marks of a general benevolence in human nature.’ (Cf. § 178 n; § 250 n.)

The fact that in the Enquiry Hume inserts a section on Benevolence (§ 2) before the treatment of Justice is in itself significant. In the Treatise benevolence is treated among the natural virtues and vices (Treatise, Bk. III, part iii, § iii, p. 602) immediately before ‘natural abilities.’ In the Enquiry it is treated as the chief of the social virtues, and though a main object of its treatment is to show its ‘utility,’ its independence is fully recognized.

But the impression produced by the comparison of such passages as the above is very much strengthened when we consider the functions and position of Sympathy in the Treatise and Enquiry respectively. It has been already noticed that in the Dissertation on the Passions sympathy was almost ignored, though it was perhaps the most important subject of Bk. II of the Treatise.

Speaking broadly, we may say that in the Treatise nothing more is clear than that sympathy is used as a solvent to reduce complex feelings to simpler elements. In the Enquiry sympathy is another name for social feeling, humanity, benevolence, natural philanthropy, rather than the name of the process by which the social feeling has been constructed out of non-social or individual feeling (§§ 180, 182, 186, 199, 203, 210, 221–3). Hume may have felt that the machinery assigned to sympathy in Bk. II of the Treatise did not work very well, and so have decided to get rid of it, but in so doing he may be said to have abandoned perhaps the most distinctive feature of his moral system as expounded in the Treatise, so that in the Enquiry there is little to distinguish his theory from the ordinary moralsense theory, except perhaps a more destructive use of ‘utility.’ In the Treatise his difference from the moralsense school lay precisely in his attempt to resolve social feeling into a simple sensitivity to pleasure and pain, which has become complicated and transformed by sympathy. In reading Hutcheson we feel that he makes out a good case for his ‘benevolence’ against Hobbes and Mandeville and the more insidious selfishness of Shaftesbury, but that it would fall an easy prey to the ‘sympathy’ of Hume’s Treatise.

Self-love is much more fully and fairly dealt with by Hume in the Enquiry than in the Treatise. He had declined, even in the Treatise, with excellent good sense, to accept the popular reduction of benevolence as given by the selfish school, but he certainly tried to reduce benevolence to something which was neither selfish nor unselfish, but rather physical.

In the Enquiry (Bk. V, §§ 173–8, and App. ii, §§ 247–254) he carries the war into the enemy’s camp, and introduces the conception of self-love which we find in Hutcheson’s later works, and especially in Butler. Section 253 is especially remarkable, insisting as it does on the necessity of appetites antecedent to self-love. The germ of the same thought is perhaps to be found in an obscure passage in the Treatise (Bk. III, part ii, § i, p. 478), though it is used for a significantly different purpose.

Benevolence is suggested in the Enquiry as the primary, and self-love as the secondary passion, and the suggestion is supported by the appeal to accept ‘the simplest and most obvious cause which can be assigned’ for any passion or operation of the human mind.

It is true that he makes even freer use of Utility in the Enquiry than in the Treatise, and that it would be easy to draw consequences from this principle which would neutralize the concessions made to benevolence, but he is content himself to leave it without developement, and to say in effect that utility pleases simply because it does please.

His tenderness towards benevolence is also seen in his treatment of Justice. In the Treatise he insisted vigorously, though not very intelligibly, that justice was not a natural but only an artificial virtue, and it is pretty plain that he meant to be offensive in doing so. His argument in the Treatise was, to say the least, awkward, and he may have been glad to get rid of an ungainly and unnecessary discussion. In the Enquiry he dismisses the question in a few words as a vain one (§ 258), and contents himself with pointing out the superior sociality of justice as compared with benevolence (§§ 255–6).

Reason. He devotes much less space in the Enquiry to proving that moral distinctions are not derived from reason, than to showing that they are derived from a sentiment of humanity. He is more tolerant to the claims of reason, and shows some approach to the indifference of Butler. ‘These arguments on each side are so plausible that I am apt to suspect they may, the one as well as the other, be solid and satisfactory, and that reason and sentiment concur in almost all moral determinations and conclusions’ (§ 137). In the same place he gives reason an important function in the correction of our sentiments of moral and natural beauty, a point which is of great importance in the moral philosophy of that time, and indeed was not ignored in the Treatise. Similarly in the Treatise he laid some stress on the identity of what was usually called ‘reason’ with the calm passions (Bk. II, part iii, § iii, p. 417; ib. § viii, p. 437), whereas he only mentions it incidentally in the Enquiry in connexion with strength of mind (§ 196).

The old difficulty about ‘general rules,’ ‘the general and unalterable point of view,’ re-appears in the Enquiry, though I think it is dealt with in a manner quite foreign to the Treatise. In the Treatise the universality of our moral judgements and their detachment from private interest was accounted for by sympathy (Treatise, Bk. III, part ii, § ii, p. 500; Bk. III, part iii, § i, p. 577; § vi, p. 618). But sympathy itself varies with time, place and person, and consequently requires correction, which is supplied by the use of general rules (Bk. III, part iii, § i, pp. 581–5). How these corrective rules are obtained he does not explain in the Treatise, and indeed they seem to work in a circle with sympathy. In the Enquiry they again appear, and are in the first place ascribed to the ‘intercourse of sentiments in society and conversation’ (§ 186), arising apparently in the same way as ‘general ideas,’ which are really only particular ideas with their particularity rubbed off by wear and tear. But in §§ 221–2 of the Enquiry he asserts the universality of moral judgements in quite a new style. ‘The notion of morals implies some sentiment common to all mankind which recommends the same object to general approbation and makes every man, or most men, agree in the same opinion or decision concerning it. It also implies some sentiment, so universal and comprehensive as to extend to all mankind, and render the actions and conduct even of persons the most remote, an object of applause and censure. . . . These two requisites belong alone to the sentiment of Humanity.’ This sentiment is the only ‘universal principle of the human frame,’ and ‘can alone be the foundation of morals or of any general system of blame or praise.’ ‘One man’s ambition is not another’s ambition, nor will the same event or object satisfy both: but the humanity of one man is the humanity of every one, and the same object touches the passion in all human creatures.’ This may not be the ‘moral sense,’ but it certainly is not the doctrine of the Treatise.

There does not seem to be any trace in the Enquiry of the appeal to the ‘natural and usual force of the passions,’ as the standard of morals, of which considerable use is made in the Treatise, and which has been considered to brand Hume’s moral system as one of sheer respectability (Treatise, Bk. III, part ii, § i, pp. 483–4; § ii, p. 488; § v, p. 518; § vi, p. 532).

The interest of Hume’s philosophical writings must not be judged by the dryness of the foregoing discussion of them. The question of the relation of the two versions with which Hume himself has endowed and puzzled us, appears of sufficient general interest to warrant a serious examination. But such questions cannot be decided by general impressions, and this Introduction aims at supplying, or rather indicating, the material for a more exact determination of Hume’s relations to himself, than has been previously attempted. The writer has also had the temerity to relieve the rather mechanical toil of tabulating differences and correspondences by attempts to distinguish the purely philosophical from the non-philosophical and personal considerations which influenced a philosopher who was often both more and less than a philosopher. How much in the matter and manner of Hume’s work is due to peculiarities of his character is hard to say, but the personal element continually challenges, even if it eludes, our appreciation.

The Introduction undoubtedly supposes that the reader has some acquaintance with the Treatise, and may serve as a guide to those students who wish to see for themselves what Hume’s last word on philosophy was. The present Edition also is intended rather as a recognition of that wish than as a concession to those who would substitute the Enquiries for the Treatise as the authoritative exposition of Hume’s system. It would be a considerable misfortune for our native philosophy if the Treatise were left unread. But the Treatise is hard, and many of us are weak, and it is better to read Hume in the Enquiries than not to read him at all. By those who begin on the Enquiries the Introduction may be read, as it were, backwards, and it may, perhaps, serve to point out the road to a fuller knowledge of a philosopher, who, at his greatest, is very great indeed.

Oxford,Nov. 1893.

Comparative Tables of the Contents of the Treatise and of the Enquiries and Dissertation on the Passions.

TABLE I.

Comparison of the Enquiry Concerning Human Understanding (according to the marginal sections of the present edition), with Book I of the Treatise on Human Nature (according to the pages of the Clarendon Press edition, Oxford, 1888 and 1896).

TABLE II.

Comparison of Book II of the Treatise on Human Nature (according to the pages of the Clarendon Press edition), with the Dissertation on the Passions (according to the pages of the collected edition of 1777, London, vol. ii).

TABLE III.

Comparison of the Enquiry Concerning the Principles of Morals with Book III of the Treatise on Human Nature.

ADVERTISEMENT

Most of the principles, and reasonings, contained in this volume, were published in a work in three volumes, calledA Treatise of Human Nature:A work which the Author had projected before he left College, and which he wrote and published not long after. But not finding it successful, he was sensible of his error in going to the press too early, and he cast the whole anew in the following pieces, where some negligences in his former reasoning and more in the expression, are, he hopes, corrected. Yet several writers, who have honoured the Author’s Philosophy with answers, have taken care to direct all their batteries against that juvenile work, which the Author never acknowledged, and have affected to triumph in any advantages, which, they imagined, they had obtained over it: A practice very contrary to all rules of candour and fair-dealing, and a strong instance of those polemical artifices, which a bigotted zeal thinks itself authorized to employ. Henceforth, the Author desires, that the following Pieces may alone be regarded as containing his philosophical sentiments and principles.

AN ENQUIRY concerning HUMAN UNDERSTANDING

SECTION I.

of the different species of philosophy.

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.

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

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.

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

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

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

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

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

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

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

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

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.

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

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

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

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

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

SECTION II.

of the origin of ideas.

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

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

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.

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

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

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.

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

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.

Here, therefore, is a proposition, which not only seems, in itself, simple and intelligible; but, if a proper use were made of it, might render every dispute equally intelligible, and banish all that jargon, which has so long taken possession of metaphysical reasonings, and drawn disgrace upon them. All ideas, especially abstract ones, are naturally faint and obscure: the mind has but a slender hold of them: they are apt to be confounded with other resembling ideas; and when we have often employed any term, though without a distinct meaning, we are apt to imagine it has a determinate idea annexed to it. On the contrary, all impressions, that is, all sensations, either outward or inward, are strong and vivid: the limits between them are more exactly determined: nor is it easy to fall into any error or mistake with regard to them. When we entertain, therefore, any suspicion that a philosophical term is employed without any meaning or idea (as is but too frequent), we need but enquire, from what impression is that supposed idea derived? And if it be impossible to assign any, this will serve to confirm our suspicion. By bringing ideas into so clear a light we may reasonably hope to remove all dispute, which may arise, concerning their nature and reality1 .

SECTION III.

of the association of ideas.

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

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 original1 : the mention of one apartment in a building naturally introduces an enquiry or discourse concerning the others2 : and if we think of a wound, we can scarcely forbear reflecting on the pain which follows it3 . 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 possible4 . 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.

SECTION IV.

sceptical doubts concerning the operations of the understanding.

Part I.

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.

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

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

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

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.

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

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

But to convince us that all the laws of nature, and all the operations of bodies without exception, are known only by experience, the following reflections may, perhaps, suffice. Were any object presented to us, and were we required to pronounce concerning the effect, which will result from it, without consulting past observation; after what manner, I beseech you, must the mind proceed in this operation? It must invent or imagine some event, which it ascribes to the object as its effect; and it is plain that this invention must be entirely arbitrary. The mind can never possibly find the effect in the supposed cause, by the most accurate scrutiny and examination. For the effect is totally different from the cause, and consequently can never be discovered in it. Motion in the second Billiard-ball is a quite distinct event from motion in the first; nor is there anything in the one to suggest the smallest hint of the other. A stone or piece of metal raised into the air, and left without any support, immediately falls: but to consider the matter a priori, is there anything we discover in this situation which can beget the idea of a downward, rather than an upward, or any other motion, in the stone or metal?

And as the first imagination or invention of a particular effect, in all natural operations, is arbitrary, where we consult not experience; so must we also esteem the supposed tie or connexion between the cause and effect, which binds them together, and renders it impossible that any other effect could result from the operation of that cause. When I see, for instance, a Billiard-ball moving in a straight line towards another; even suppose motion in the second ball should by accident be suggested to me, as the result of their contact or impulse; may I not conceive, that a hundred different events might as well follow from that cause? May not both these balls remain at absolute rest? May not the first ball return in a straight line, or leap off from the second in any line or direction? All these suppositions are consistent and conceivable. Why then should we give the preference to one, which is no more consistent or conceivable than the rest? All our reasonings a priori will never be able to show us any foundation for this preference.

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

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.

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.

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

I shall content myself, in this section, with an easy task, and shall pretend only to give a negative answer to the question here proposed. I say then, that, even after we have experience of the operations of cause and effect, our conclusions from that experience are not founded on reasoning, or any process of the understanding. This answer we must endeavour both to explain and to defend.

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 powers1 and principles, we always presume, when we see like sensible qualities, that they have like secret powers, and expect that effects, similar to those which we have experienced, will follow from them. If a body of like colour and consistence with that bread, which we have formerly eat, be presented to us, we make no scruple of repeating the experiment, and foresee, with certainty, like nourishment and support. Now this is a process of the mind or thought, of which I would willingly know the foundation. It is allowed on all hands that there is no known connexion between the sensible qualities and the secret powers; and consequently, that the mind is not led to form such a conclusion concerning their constant and regular conjunction, by anything which it knows of their nature. As to past Experience, it can be allowed to give direct and certain information of those precise objects only, and that precise period of time, which fell under its cognizance: but why this experience should be extended to future times, and to other objects, which for aught we know, may be only in appearance similar; this is the main question on which I would insist. The bread, which I formerly eat, nourished me; that is, a body of such sensible qualities was, at that time, endued with such secret powers: but does it follow, that other bread must also nourish me at another time, and that like sensible qualities must always be attended with like secret powers? The consequence seems nowise necessary. At least, it must be acknowledged that there is here a consequence drawn by the mind; that there is a certain step taken; a process of thought, and an inference, which wants to be explained. These two propositions are far from being the same, I have found that such an object has always been attended with such an effect, and I foresee, that other objects, which are, in appearance, similar, will be attended with similar effects. I shall allow, if you please, that the one proposition may justly be inferred from the other: I know, in fact, that it always is inferred. But if you insist that the inference is made by a chain of reasoning, I desire you to produce that reasoning. The connexion between these propositions is not intuitive. There is required a medium, which may enable the mind to draw such an inference, if indeed it be drawn by reasoning and argument. What that medium is, I must confess, passes my comprehension; and it is incumbent on those to produce it, who assert that it really exists, and is the origin of all our conclusions concerning matter of fact.

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 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 à 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.

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