A Treatise of Human Nature · David Hume
GENERAL INTRODUCTION TO VOL. I.
All propositions restricted in same way as Locke’s propositions about real existence. 223. A customary sequence, then, of individual ideas upon each other is the reality, which through the delusion of words (as we must suppose) has given rise to the fiction of there being such a thing as general knowledge. We say ‘fiction,’ for with the possibility of general propositions, as the Greek philosophers once for all pointed out, stands or falls the possibility of science. Locke was so far aware of this that, upon the same principle which led him to deny the possibility of general propositions concerning real existence, he ‘suspected’ a science of nature to be impossible, and only found an exemption for moral and mathematical truth from this condemnation in its ‘bare ideality.’ Hume does away with the exemption. He applies to all propositions alike the same limitation which Locke applies to those concerning real existence. With Locke there may very well be a proposition which to the mind, as well as in form, is general--one of which the subject is an ‘abstract general idea’--but such proposition ‘concerns not existence.’ As knowledge of real existence is limited to the ‘actual present sensation,’ so a proposition about such existence is limited to what is given in such sensation.
It is a real truth that this piece of gold is now being dissolved in aqua regia, when the ‘particular experiment’ is going on under our eyes, but the general proposition ‘gold is soluble’ is only an analysis of a nominal essence. With Hume the distinction between propositions that do, and those that do not, ‘concern existence’ disappears. Every proposition is on the same footing in this respect, since it must needs be a statement about an ‘idea,’ and every idea exists. ‘Every object that is presented must necessarily be existent. ... Whatever we conceive, we conceive to be existent. Any idea we please to form is the idea of a being; and the idea of a being is any idea we please to form’. [1] But since, according to him, the idea cannot be separated, as Locke supposed it could, from the conditions ‘that determine it to this or that particular existence,’ propositions of the sort which Locke understood by ‘general propositions concerning substances,’ though if they were possible they would ‘concern existence’ as much as any, are simply impossible. Hume, in short, though he identifies the real and nominal essences which Locke had distinguished, yet limits the nominal essence by the same ‘particularity in space and time’ by which Locke had limited the real. [1] p. 370 [Book I, part II., sec. VI.]
The question, how the _singular_ proposition is possible, the vital one. 224. A great advance in simplification has been made when the false sort of ‘conceptualism’ has thus been got rid of--that conceptualism which opposes knowing and being under the notion that things, though merely individual in reality, may be known as general. This riddance having been achieved, as it was by Hume, the import of the proposition becomes the central question of philosophy, the answer to which must determine our theory of real existence just as much as of the mind. The issue may be taken on the proposition in its singular no less than in its general form. The weakness of Hume’s opponents, indeed, has lain primarily in their allowing that his doctrine would account for any significant predication whatever, as distinct from exclamations prompted by feelings as they occur. This has been the inch, which once yielded, the full ell of his nominalism has been easily won; just as Locke’s empiricism becomes invincible as soon as it is admitted that qualified things are ‘found in nature’ without any constitutive action of the mind. As the only effective way of dealing with Locke is to ask,--After abstraction of all that he himself admitted to be the creation of thought, what remains to be merely found?--so Hume must be met _in limine_ by the question whether, apart from such ideas of relation as according to his own showing are not simple impressions, so much as the singular proposition is possible. If not, then the singularity of such proposition does not consist in any singleness of presentation to sense; it is not the ‘particularity in time’ of a present feeling; and the exclusion of generality, whether in thoughts or in things, as following from the supposed necessity of such singleness or particularity, is quite groundless.
Not relations of resemblance only, but those of quantity also, treated by Hume as feelings. 225. Hitherto the idea of relation which we have had specially in view has been that of relation in the way of resemblance, and the propositions have been such as represent the most obvious ‘facts of observation’--facts about this or that ‘body,’ man or horse or ball. We have seen that these already suppose the thought of an object qualified, not transitory as are feelings, but one to which feelings are referred on their occurrence as resemblances or differences between it and other objects; but that by an equivocation, which unexamined phraseology covers, between the thought of such an object and feeling proper--as if because we talk of seeing a man, therefore a man were a feeling of colour--Hume is able to represent them as mere data of sense, and thus to ignore the difference between related feelings and ideas of relation. Thus the first step has been taken towards transferring to the sensitive subject, as merely sensitive, the power of thought and significant speech. The next is to transfer to it ideas of those other relations [1] which Hume classifies as ‘relations of time and place, proportion in quantity or number, degrees in any quality’. [2] This done, it is sufficiently equipped for achieving its deliverance from metaphysics. An animal, capable of experiments concerning matter of fact, and of reasoning concerning quantity and number, would certainly have some excuse for throwing into the fire all books which sought to make it ashamed of its animality. [3]
He draws the line between certainty and probability at the same point as Locke; but is more definite as to probability, 226. In thus leaving mathematics and a limited sort of experimental physics (limited by the exclusion of all general inference from the experiment) out of the reach of his scepticism, and in making them his basis of attack upon what he conceived to be the more pretentious claims of knowledge, Hume was again following the course marked out for him by Locke. It will be remembered that Locke, even when his ‘suspicion’ of knowledge is at its strongest, still finds solid ground _(a)_ in ‘particular experiments’ upon nature, expressed in singular propositions as opposed to assertions of universal or necessary connexion, and _(b)_ in mathematical truths which are at once general, certain, and instructive, because ‘barely ideal.’ All speculative propositions that do not fall under one or other of these heads are either ‘trifling’ or merely ‘probable.’ Hume draws the line between certainty and probability at the same point, nor in regard to the ground of certainty as to ‘matter of fact or existence’ is there any essential difference between him and his master. As this ground is the ‘actual present sensation’ with the one, so it is the ‘impression’ with the other; and it is only when the proposition becomes universal or asserts a necessary connection, that the certainty, thus given, is by either supposed to fail.
It is true that with Locke this authority of the sensation is a derived authority, depending on its reference to a ‘body now operating upon us,’ while with Hume, so far as he is faithful to his profession of discarding such reference, it is original. But with each alike the fundamental notion is that a feeling must be ‘true _while it lasts_,’ and that in regard to real existence or matter of fact no other truth can be known but this. Neither perceives that a truth thus restricted is no truth at all--nothing that can be stated even in a singular proposition; that the ‘particularity in time,’ on which is supposed to depend the real certainty of the simple feeling, is just that which deprives it of significance [1]--because neither is really faithful to the restriction. Each allows himself to substitute for the momentary feeling an object qualified by relations, which are the exact opposite of momentary feelings. ‘If I myself see a man walk on the ice,’ says Locke (IV, xv.
5), ‘it is past probability, it is knowledge:’ nor would Hume, though ready enough on occasion to point out that what is seen must be a colour, have any scruple in assuming that such a complex judgment as the above so-called ‘sight’ has the certainty of a simple impression. It is only in bringing to bear upon the characteristic admission of Locke’s Fourth Book, that no general knowledge of nature can be more than probable, a more definite notion of what probability is, and in exhibiting the latent inconsistency of this admission with Locke’s own doctrine of ideas as effects of a causative substance, that he modifies the theory of _physical_ certainty which he inherited. In their treatment of mathematical truths on the other hand, of propositions involving relations of distance, quantity and degree, a fundamental discrepancy appears between the two writers. The ground of certainty, which Hume admits in regard to propositions of this order, must be examined before we can appreciate his theory of probability as it affects the relations of cause and substance. [1] See above, paragraphs 45 and 97. ... and does not admit opposition of mathematical to physical certainty--here following Berkeley.
227. It has been shown [1] that Locke’s opposition of mathematical to physical certainty, with his ascription to the former of instructive generality on the ground of its bare ideality--the ‘ideal’ in this regard being opposed to what is found in sensation--strikes at the very root of his system. It implies that thought can originate, and that what it originates is in some sort real--nay, as being nothing else than the ‘primary qualities of matter,’ is the source of all other reality. Here was an alien element which ‘empiricism’ could not assimilate without changing its character. Carrying such a conception along with it, it was already charged with an influence which must ultimately work its complete transmutation by compelling, not the admission of an ideal world of guess and aspiration alongside of the empirical, but the recognition of the empirical as itself ideal The time for this transmutation, however, was not yet. Berkeley, in over-hasty zeal for God, had missed that only true way of finding God in the world which lies in the discovery that the world is Thought. Having taken fright at the ‘mathematical Atheism,’ which seemed to grow out of the current doctrines about primary qualities of matter, instead of applying Locke’s own admissions to show that these were intelligible and merely intelligible, he fancied that he had won the battle for Theism by making out that they were merely feelings or sequences of feelings. From him Hume got the text for all he had to say against the metaphysical mathematicians; but, for the reason that Hume applied it with no theological interest, its true import becomes more apparent with him than with Berkeley.
As we have seen, he supposes our ideas of sense to be from the beginning ideas of the qualities of bodies, and virtually justifies the supposition by sending the reader to his sense of touch for that idea of solidity in which, as he defines it, all the primary qualities are involved. That the sense in question does not really yield the idea is what Hume points out when he says that, ‘though bodies are felt by means of their solidity, yet the feeling is quite a different thing from the solidity, nor have they the least resemblance to each other.’ In other words, having come to suppose that there are solid bodies, we explain our feeling as due to their solidity; but we may not at once interpret feeling as the result of solidity, and treat solidity as itself a feeling. It was by allowing himself so to treat it that Locke disguised from himself the objection to his interpretation of feeling. Hume tears off the disguise, and in effect gives him the choice of being convicted either of reasoning in a circle or of explaining the simple idea by reference to the complex. The solidity, which is to explain feeling, can itself only be explained by reference to body. If body is only a complex of ideas of sense, in referring tactual feeling to it we are explaining a simple idea by reference to a compound one. If it is not, how is it to be defined except in the ‘circular’ way, which Locke in fact adopts when he makes body a ‘texture of solid parts’ and solidity a relation of bodies? [2]
Hence Hume’s attempt, reversing Locke’s derivation of ideas of sense from primary qualities of body, to derive what with Locke had been primary qualities, as compound impressions of sense, from simple impressions and to reduce body itself to a name not for any ‘just and consistent idea,’ but for a ‘propensity to feign,’ the gradual product of custom and imagination. The question by which the value of such derivation and reduction is to be tried is our old one, whether it is not a tacit conversion of the supposed original impressions into qualities of body that alone makes them seem to yield the result required of them. If the Fourth Book of the ‘Treatise on Human Nature,’ with its elimination of the idea of body, had come before the second, would not the plausibility of the account of mathematical ideas contained in the latter have disappeared? And conversely, if these ideas had been reduced to that which upon elimination of the idea of body they properly become, would not that ‘propensity to feign,’ which is to take the place of the excluded idea, be itself unaccountable? With Hume ‘body’ logically disappears. What then?
232. ‘After exclusion of colours, sounds, heat and cold, from the rank of external existences, there remains nothing which can afford us a just and consistent idea of body.’ Now, no one can ‘exclude them from the rank of external existences’ more decisively than Hume. They are impressions, and ‘all impressions are internal and perishing existences, and appear as such.’ Nor does he shirk the consequence, that we have no ‘just and consistent idea of body.’ It is true that we cannot avoid a ‘belief in its existence’--a belief which according to Hume consists in the supposition of ‘a continued existence of objects when they no longer appear to the senses, and of their existence as distinct from the mind and perceptions;’ in other words, as ‘external to and independent of us.’ This belief, however, as he shows, is not given by the senses. That we should feel the existence of an object to be continued when we no longer feel it, is a contradiction in terms; nor is it less so, that we should feel it to be distinct from the feeling. We cannot, then, have an impression of body; and, since we cannot have an idea which does not correspond to an impression or collection of impressions, it follows that we can have no idea of it. How the ‘belief in its existence’ is accounted for by Hume in the absence of any idea of it, is a question to be considered later. [1] Our present concern is to know whether the idea of extension can hold its ground when the idea of body is excluded.
According to this meaning of the words, all must admit that ‘the first notion of space and extension is derived from the senses of sight and feeling;’ though it does not follow that a repeated or continued activity of either sense is necessary to the continued presence of the notion. With Hume, however, the derivation spoken of must mean that the notion of space is, to begin with, simply a visual or tactual feeling, and that such it remains, though with indefinite abatement and revival in the liveliness of the feeling, according to the amount of which it is called ‘impression’ or ‘idea.’ If we supposed him to mean, not that the notion of space was either a visual or tactual feeling indifferently, but that it was a compound result of both, [2] we should merely have to meet a further difficulty as to the possibility of such composition of feelings when their inward synthesis in a soul, and the outward in a body, have been alike excluded. In the next clause of the sentence, however, we find that for visual and tactual feelings there are quietly substituted ‘coloured and tangible objects, having parts so disposed as to convey the idea of extension.’ It is in the light of this latter clause that the uncritical reader interprets the former.
He reads back the plausibility of the one into the other, and, having done so, finds the whole plausible. Now this plausibility of the latter clause arises from its implying a three-fold distinction--a distinction of colour or tangibility on the one side from the disposition of the parts on the other; a distinction of the colour, tangibility and disposition of parts alike from an object to which they belong; and a distinction of this object from the idea that it conveys. In other words, it supposes a negative answer to the three following questions:--Is the idea of extension the same as that of colour or tangibility? Is it possible without reference to something other than a possible impression? Is the idea of extension itself extended? Yet to the two latter questions, according to Hume’s express statements, the answer must be affirmative; nor can he avoid the affirmative answer to the first, to which he would properly be brought, except by equivocation. [1] [Greek ἄπειρον (apeiron) = unlimited, indefinite or infinite. Tr.] [2] It is not really in this sense that the impression of space according to Hume is a ‘compound’ one, as will appear below. It means, in effect, that colour and space are the same, and that feeling may be extended.
234. The _pièces justificatives_ for this assertion are not far to seek. Some of them have been adduced already. The idea of space, like every other idea, must be a ‘copy of an impression.’ [1] To speak of a feeling in its fainter stage as an ‘image’ of what it was in its livelier stage may, indeed, seem a curious use of terms; but in this sense only, according to Hume’s strict doctrine, can the idea of space be spoken of as an ‘image’ of anything at all. The impression from which it is derived, _i.e._ the feeling at its liveliest, cannot properly be so spoken of, for ‘no impression is presented by the senses as the image of anything distinct, or external, or independent.’ [2] If no impression is so presented, neither can any idea, which copies the impression, be so. It can involve no reference to anything which does not come and go with the impression. Accordingly no distinction is possible between space on the one hand, and either the impression or idea of it on the other. All impressions and ideas that can be said to be of extension must be themselves extended; and conversely, as Hume puts it, ‘all the qualities of extension are qualities of a perception.’ It should follow that space is either a colour or feeling of touch. In the terms which Hume himself uses with reference to ‘substance,’ ‘if it be perceived by the eyes, it must be colour; if by the ears, a sound; and so on, of the other senses.’ As he expressly tells us that it is ‘perceived by the eyes,’ the conclusion is inevitable.
236. In order to a proper appreciation of this passage it is essential to bear in mind that Hume, so far as the usages of language would allow him, ignores all such differences in modes of consciousness as the Germans indicate by the distinction between ‘Empfindung’ and ‘Vorstellung,’ and by that between ‘Anschauung’ and ‘Begriff;’ or, more properly, that he expressly merges them in a mode of consciousness for which, according to the most consistent account that can be gathered from him, the most natural term would be ‘feeling.’ [1] It is true that Hume himself, admitting a distinction in the degree of vivacity with which this consciousness is at different times presented, inclines to restrict the term ‘feeling’ to its more vivacious stage, and to use ‘perception’ as the more general term, applicable whatever the degree of vivacity may be. [2] We must not allow him, however, in using this term to gain the advantage of a meaning which popular theory does, but his does not, attach to it. ‘Perception’ with him covers ‘idea’ as well as ‘impression;’ but nothing can be said of idea that cannot be said of impression, save that it is less lively, nor of impression that cannot be said of idea, save that it is more so.
It is this explicit reduction of all consciousness virtually, if not in name, to feeling that brings to the surface the difficulties latent in Locke’s ‘idealism.’ These we have already traced at large; but they may be summed up in the question, How can feelings, as ‘particular in time’ or (which is the same) in ‘perpetual flux,’ constitute or represent a world of permanent relations? [3] The difficulty becomes more obvious, though not more real, when the relations in question are not merely themselves permanent, like those between natural phenomena, but are ‘relations between permanent parts,’ like those of space. It is for this reason that its doctrine about geometry has always been found the most easily assailable point of the ‘sensational’ philosophy. Locke distinguishes the ideas of space and of duration as got, the one ‘from the permanent parts of space,’ the other ‘from the fleeting and perpetually perishing parts of succession.’ [4] He afterwards prefers the term ‘expansion’ to space, as the opposite of duration, because it brings out more clearly the distinction of a relation between permanent parts from that between ‘fleeting successive parts which never exist together.’ How, then, can a consciousness consisting simply of ‘fleeting successive parts’ either be or represent that of which the differentia is that its parts are permanent and co-exist? [1] As implying no distinction from, or reference to, a thing causing and a subject experiencing it. See above, paragraphs 195 and 208, and the passages there referred to.
To make sense of them, we must take perception to mean perceived thing, 239. To this a follower of Hume, if he could be brought to admit the legitimacy of depriving his master of the benefit of synonyms, might probably reply, that the apparent nonsense only arises from our being unaccustomed to such use of the term ‘feeling;’ that the table is a ‘bundle of feelings,’ actual and possible, of which the actual one of sight suggests a lively expectation, easily confused with the presence, of the others belonging to the other senses; that any one of these may be considered a quality of the total impression formed by all; that the feeling thus considered, if it happens to be visual, may not improperly be said to consist of other feelings, as a whole consists of parts, since it is the result of impressions on different parts of the retina, and from a different point of view even itself to be the relation between the parts, just as naturally as a mutual feeling of friendship may be said either to consist of the loves of the two parties to the friendship, or to constitute the relation between them. Such language represents those modern adaptations of Hume, which retain his identification of the real with the felt but ignore his restrictions on the felt.
Text from Project Gutenberg, public domain in the United States.