A Treatise of Human Nature · David Hume
GENERAL INTRODUCTION TO VOL. I.
Along with this conversion, there supervenes upon the original distinction between simple and complex ideas, which alone does duty in the Second Book of the Essay, another distinction, essential to Locke’s doctrine of the ‘reality’ of knowledge--that between the idea, whether simple or complex, as originally given in sensation, and the same as retained or reproduced in the mind. It is only in the former form that the idea, however simple, reports, and thus (with Locke) itself is, a real existence. Such real existence is a ‘particular’ existence, and our knowledge of it a ‘particular’ knowledge. In other words, according to the only consistent doctrine that we have been able to elicit from Locke, [2] ‘it is a knowledge which consists in a consciousness, upon occasion of a present sensation--say, a sensation of redness--that some object is present here and now causing the sensation; an object which, accordingly, must be ‘particular’ or transitory as the sensation. The ‘here and now,’ as in such a case they constitute the particularity of the object of consciousness, so also render it a real existence. Separate these (‘the circumstances of time and place’ [3]) from it, and it at once loses its real existence and becomes an ‘abstract idea,’ one of ‘our own thoughts,’ of which as ‘in the mind’ agreement or disagreement with some other abstract idea can be asserted in a general proposition; _e.g._ ‘red is not blue.’ (Book IV. chap. vii. sec. 4.) [4]
Nothing as to their recurrence, because, though in each case they show the presence of something causing the sensations, they show nothing of the real essence upon which their recurrence depends. [2] Nothing as to any permanently real relation between them, because, although the disagreement between ideas of blue and red, and the agreement between one idea of red and another, _as in the mind_, is self-evident, yet as thus in the mind they are not ‘actual sensations’ at all (Book IV. chap. xi. sec. 6), nor do they convey that ‘sensitive knowledge of particular existence,’ which is the only possible knowledge of it. (Book IV. chap. iii. sec. 21.) As actual sensations and indices of reality, they do indeed differ in this or that ‘bare instance,’ but can convey no certainty that the real thing or ‘parcel of matter’ (Book III. chap. iii. sec. 18), which now causes the sensation of (and thus _is_) red, may not at another time cause the sensation of (and thus _be_) blue.’ [3] [1] Already in Book II. (chap. xxxi. sec. 12), the simple idea, as abstract, is spoken of as a nominal essence. [2] Cf. Book IV. chap. vi. sec. 5. ‘If we could certainly know (which is impossible) where a real essence, which we know not, is--_e.g._ in what parcels of matter the real essence of gold is; yet could we not be sure, that this or that quality could with truth be affirmed of gold; since it is impossible for us to know that this or that quality or idea has a necessary connexion with a real essence, of which we have no idea at all.’
Several passages, of course, can be adduced from Locke which are inconsistent with the statement in the text: _e.g._ Book IV. chap. iv. sec. 12. ‘To make knowledge real concerning substances, the ideas must be taken from the real existence of things. Whatever simple ideas have been found to coexist in any substance, these we may with confidence join together again, and so make abstract ideas of substances. For whatever have once had an union in nature, may be united again.’ In all such passages, however, as will appear below, the strict opposition between the real and the mental is lost sight of, the ‘nature’ or ‘substance,’ in which ideas ‘have a union,’ or are ‘found to coexist,’ being a system of relations which, according to Locke, it requires a mind to constitute, and thus itself a ‘nominal essence.’ [3] Cf. Book IV. chap. iii. sec. 29; Book IV. chap. vi. sec. 14; Book IV. chap. xi. sec. 11. How then is science of nature possible? 83. We thus come upon the crucial antithesis between relations of ideas and matters of fact, with the exclusion of general certainty as to the latter, which was to prove such a potent weapon of scepticism in the hands of Hume. Of its incompatibility with recognized science we can have no stronger sign than the fact that, after more than a century has elapsed since Locke’s premisses were pushed to their legitimate conclusion, the received system of logic among us is one which, while professing to accept Locke’s doctrine of essence, and with it the antithesis in question, throughout assumes the possibility of general propositions as to matters of fact, and seeks in their methodical discovery and proof that science of nature which Locke already ‘suspected’ to be impossible. (Book IV. chap. xii. sec. 10.)
No ‘uniformities of phenomena’ can be known. 84. That, so far as any inference from past to future uniformities is necessary to the science of nature, his doctrine does more than justify such ‘suspicion,’ is plain enough. Does it, however, leave room for so much as a knowledge of past uniformities of fact, in which the natural philosopher, accepting the doctrine, might probably seek refuge? At first sight, it might seem to do so. ‘As, when our senses are actually employed about any object, we do know that it does exist; so by our memory we may be assured that heretofore things that affected our senses have existed--and thus we have knowledge of the past existence of several things, whereof our senses having informed us, our memories still retain the ideas.’ (Book IV. chap. xi. sec. 11.) Let us see, however, how this knowledge is restricted. ‘Seeing water at this instant, it is an unquestionable truth to me that water doth exist; and remembering that I saw it yesterday, it will also be always true, and as long as my memory retains it, always an undoubted proposition to me, that water did exist the 18th of July, 1688; as it will also be equally true that a certain number of very fine colours did exist, which at the same time I saw on a bubble of that water; but being now quite out of sight both of the water and bubbles too, it is no more certainly known to me that the water doth now exist, than that the bubbles and colours therein do so; it being no more necessary that water should exist to-day because it existed yesterday, than that the colours or bubbles exist to-day because they existed yesterday.’ (_Ibid_.)
Locke not aware of the full effect of his own doctrine ... 85. The result is that though I may enumerate a multitude of past matters-of-fact about water, I cannot gather them up in any general statement about it as a real existence. So soon as I do so, I pass from water as a real existence to its ‘nominal essence,’ _i.e._, to the ideas retained in my mind and put together in a fictitious substance, to which I have annexed the name ‘water.’ If we proceed to apply this doctrine to the supposed past matters-of-fact themselves, we shall find these too attenuating themselves to nonentity. Subtract in every case from the ‘particular existence’ of which we have ‘sensitive knowledge’ the qualification by ideas which, as retained in the mind, do not testify to a present real existence, and what remains? There is a certainty, according to Locke (Book IV. chap. xi. sec. 11), not, indeed, that water exists to-day because it existed yesterday--this is only ‘probable’--but that it has, as a past matter-of-fact, at this time and that ‘continued long in existence,’ because this has been ‘observed;’ which must mean (Book IV. chap. ii. secs. 1, 5, and 9), because there has been a continued ‘actual sensation’ of it.
‘Water,’ however, is a complex idea of a substance, and of the elements of this complex idea those only which at any moment are given in ‘actual sensation’ may be accounted to ‘really exist.’ First, then, must disappear from reality the ‘something,’ that unknown substratum of ideas, of which the idea is emphatically ‘abstract.’ This gone, we naturally fall back upon a fact of co-existence between ideas, as being a reality, though the ‘thing’ be a fiction. But if this co-existence is to be real or to represent a reality, the ideas between which it obtains must be ‘actual sensations.’ These, whatever they may be, are at least opposed by Locke to ideas retained in the mind, which only form a nominal essence. But it is the association of such nominal essence, in the supposed observation of water, with the actual sensation that alone gives the latter a meaning. Set this aside as unreal, and the reality, which the sensation reveals, is at any rate one of which nothing can be said. It cannot be a relation between sensations, for such relation implies a consideration of them by the mind, whereby, according to Locke, they must cease to be ‘real existences.’
(Book II. chap. xxv. sec. 1.) It cannot even be a single sensation _as continuously observed_, for every present moment of such observation has at the next become a past, and thus the sensation observed in it has lost its ‘actuality,’ and cannot, _as a ‘real existence_,’ qualify the sensation observed in the next. Restrict the ‘real existence,’ in short, as Locke does, to an ‘actual present sensation,’ which can only be defined by opposition to an idea retained in the mind, and at every instant of its existence it has passed into the mind and thus ceased really to exist. Reality is in perpetual process of disappearing into the unreality of thought. No point can be fixed either in the flux of time or in the imaginary process from ‘without’ to ‘within’ the mind, on the one side of which can be placed ‘real existence,’ on the other the ‘mere idea.’ It is only because Locke unawares defines to himself the ‘actual sensation’ as representative of a real essence, of which, however, according to him, as itself unknown, the presence is merely inferred from the sensation, that the ‘actual sensation’ itself is saved from the limbo of nominal essence, to which ideas, as abstract or in the mind, are consigned. Only, again, so far as it is thus illogically saved, are we entitled to that distinction between ‘facts’ and ‘things of the mind,’ which Locke once for all fixed for English philosophy.
Ground of distinction between actual sensation and ideas in the mind is itself a thing of the mind. 87. We have already seen how Locke, in his doctrine of secondary qualities of substances, practically gets over this difficulty; how he first projects out of the simple ideas, under relations which it requires a mind to constitute, a cognisable system of things, and then gives content and definiteness to the simple ideas in us by treating them as manifestations of this system of things. In the doctrine of propositions, the proper correlative to the reduction of the real to the present simple idea, as that of which we cannot get rid, would be the reduction of the ‘real proposition’ to the mere ‘it is now felt.’ If the matter-of-fact is to be that in consciousness which is independent of the ‘work of the mind’ in comparing and compounding, this is the only possible expression for it. It states the only possible ‘real essence,’ which yet is an essence of nothing, for any reference of it to a thing, if the thing is outside consciousness, is an impossibility; and if it is within consciousness, implies an ‘invention of the mind’ both in the creation of a thing, ‘always the same with itself,’ out of perishing feelings, and in the reference of the feelings to such a thing.
Thus carried out, the antithesis between ‘fact’ and ‘creation of the mind’ becomes self-destructive, for, one feeling being as real as another, it leaves no room for that distinction between the real and fantastic, to the uncritical sense of which it owes its birth. To avoid this fusion of dream-land and the waking world, Locke avails himself of the distinction between the idea (_i.e._ feeling) as in the mind, which is not convertible with reality, and the idea as somewhere else, no one can say where--‘the actual sensation’--which is so convertible. The distinction, however, must either consist in degrees of liveliness, in which case there must be a corresponding infinity of degrees of reality or unreality, or else must presuppose a real existence from which the feeling, if ‘actual sensation,’ _is_--if merely ‘in the mind’ _is not_--derived. Such a real existence either is an object of consciousness, or is not. If it is not, no distinction between one kind of feeling and another can for consciousness be derived from it. If it is, then, granted the distinction between given feelings and creations of the mind, it must fall to the latter, and a ‘thing of the mind’ turns out to be the ground upon which ‘fact’ is opposed to ‘things of the mind.’ Two meanings of real essence.
88. It remains to exhibit briefly the disguises under which these inherent difficulties of his theory of essence appear in Locke. Throughout, instead of treating ‘essence’ altogether as a fiction of the mind--as it must be if feelings in simplicity and singleness are alone the real--he treats indeed as a merely ‘nominal essence’ every possible combination of ideas of which we can speak, but still supposes another essence which is ‘real.’ But a real essence of what? Clearly, according to his statements, of the same ‘thing’ of which the combination of ideas in the mind is the nominal essence. Indeed, there is no meaning in the antithesis unless the ‘something,’ of which the latter essence is so nominally, is that of which it is not so really. So says Locke, ‘the nominal essence of gold is that complex idea the word gold stands for; let it be, for instance, a body yellow, of a certain weight, malleable, fusible, and fixed. But the real essence is the constitution of the insensible parts _of that body_, on which those qualities and all the other properties of gold depend.’ (Book III. chap. vi. sec. 2.) Here the notion clearly is that of one and the same thing, of which we can only say that it is a ‘body,’ a certain complex of ideas--yellowness, fusibility, &c.--is the nominal, a certain constitution of insensible parts the real, essence. It is on the real essence, moreover, that the ideas which constitute the nominal depend. Yet while they are known, the real essence (as appears from the context) is wholly unknown. In this case, it would seem, the cause is not known from its effects.
According to one, it is a collection of ideas as qualities of a thing: 89. There are lurking here two opposite views of the relation between the nominal essence and the real thing. According to one view, which prevails in the later chapters of the Second Book and in certain passages of the third, the relation between them is that with which we have already become familiar in the doctrine of substance--that, namely, between ideas as in us and the same as in the thing. (Book II, chap. xxiii. secs. 9 and 10.) No distinction is made between the ‘idea in the mind’ and the ‘actual sensation.’ The ideas in the mind are also in the thing, and thus are called its qualities, though for the most part they are so only secondarily, _i.e._ as effects of other qualities, which, as copied directly in our ideas, are called primary, and relatively to these effects are called powers. These powers have yet innumerable effects to produce in us which they have not yet produced. (Book II. chap. xxxi. sec. 10.) Those which have been so far produced, being gathered up in a complex idea to which a name is annexed, form the ‘nominal essence’ of the thing. Some of them are of primary qualities, more are of secondary.
The originals of the former, the powers to produce the latter, together with powers to produce an indefinite multitude more, will constitute the ‘real essence,’ which is thus ‘a standard made by nature,’ to which the nominal essence is opposed merely as the inadequate to the adequate. The ideas, that is to say, which are indicated by the name of a thing, have been really ‘found in it’ or ‘produced by it,’ but are only a part of those that remain to be found in it or produced by it. It is in this sense that Locke opposes the adequacy between nominal and real essence in the case of mixed modes to their perpetual inadequacy in the case of ideas of substances. The combination in the one case is artificially made, in the other is found and being perpetually enlarged. This he illustrates by imagining the processes which led Adam severally to the idea of the mixed mode ‘jealousy’ and that of the substance ‘gold.’ In the former process Adam ‘put ideas together only by his own imagination, not taken from the existence of anything ... the standard there was of his own making.’ In the latter, ‘he has a standard made by nature; and therefore being to represent that to himself by the idea he has of it, even when it is absent, he puts no simple idea into his complex one, but what he has the perception of from the thing itself. He takes care that his idea be conformable to this archetype.’ (Book III. chap. vi. secs. 46, 47.) ‘It is plain,’ however, ‘that the idea made after this fashion by this archetype will be always inadequate.’
These qualities, as in the thing, doubtless would not be, as in us, feelings (or, as Locke should rather have said in more recent phraseology, possibilities of feeling), but powers to produce feeling, nor could any relation between these, as in the thing, be affirmed but such as had produced its copy or effect in actual experience. No coexistence of qualities could be truly affirmed, which had not been found; but, once found--being a coexistence of qualities and not simply a momentary coincidence of feelings--it could be affirmed as permanent in a general proposition. That a relation can be stated universally between ideas collected in the mind, no one denies, and if such collection ‘is taken from a combination of simple ideas _existing together constantly in things_’ (Book II. chap, xxxii. sec. 18), the statement will hold equally of such existence. Thus Locke contrasts mixed modes, which, for the most part, ‘being actions which perish in the birth, are not capable of a lasting duration,’ with ‘substances, which are the actors; and wherein the simple ideas that make up the complex ideas designed by the name have a lasting union.’ (Book III. chap. vi. sec. 42.) [1] Book II. chap. xxxi. sec. 12. But such real essence a creature of thought.
91. In such a doctrine Locke, starting whence he did, could not remain at rest. We need not here repeat what has been said of it above in the consideration of his doctrine of substance. Taken strictly, it implies that ‘real existence’ consists in a permanent relation of ideas, said to be of secondary qualities, to each other in dependence on other ideas, said to be of primary qualities. In other words, in order to constitute reality, it takes ideas out of that particularity in time and place, which is yet pronounced the condition of reality, to give them an ‘abstract generality’ which is fictitious, and then treats them as constituents of a system of which the ‘invented’ relations of cause and effect and of identity are the framework. In short, it brings reality wholly within the region of thought, distinguishing it from the system of complex ideas or nominal essences which constitute our knowledge, not as the unknown opposite of all possible thought, but only as the complete from the incomplete. To one who logically carried out this view, the ground of distinction between fact and fancy would have to be found in the relation between thought as ‘objective,’ or in the world, and thought as so far communicated to us. Here, however, it could scarcely be found by Locke, with whom ‘thought’ meant simply a faculty of the ‘thinking thing,’ called a ‘soul,’ which might ride in a coach with him from Oxford to London. (Book II. chap, xxiii. sec. 20.) Was the distinction then to disappear altogether?
Hence another view of real essence as unknown qualities of unknown body. 92. It is saved, though at the cost of abandoning the ‘new way of ideas,’ as it had been followed in the Second Book, by the transfer of real existence from the thing in which ideas are found, and whose qualities the complex of ideas in us, though inadequate, represents, to something called ‘body,’ necessarily unknown, because no ideas in us are in any way representative of it. To such an unknown body unknown qualities are supposed to belong under the designation ‘real essence.’ The subject of the nominal essence, just because its qualities, being matter of knowledge, are ideas in our minds, is a wholly different and a fictitious thing. How Locke mixes up these two meanings in ambiguity about body.
93. This change of ground is of course not recognized by Locke himself. It is the perpetual crossing of the inconsistent doctrines that renders his ‘immortal Third Book’ a web of contradictions. As was said above, he constantly speaks as if the subject of the real essence were the same with that of the nominal, and never explicitly allows it to be different. The equivocation under which the difference is disguised lies in the use of the term ‘body.’ A ‘particular body’ is the subject both of the nominal and real essence ‘gold’ But ‘body,’ as that in which ‘ideas are found,’ and in which they permanently coexist according to a natural law, is one thing; ‘body,’ as the abstraction of the unknown, is quite another. It is body in the former sense that is the real thing when nominal essence (the complex of ideas in us) is treated as representative, though inadequately so, of the real thing; it is body in the latter sense that is the real thing when this is treated as wholly outside possible consciousness, and its essence as wholly unrepresented by possible ideas. By a jumble of the two meanings Locke obtains an amphibious entity which is at once independent of relation to ideas, as is body in the latter sense, and a source of ideas representative of it, as is body in the former sense--which thus carries with it that opposition to the mental which is supposed necessary to the real, while yet it seems to manifest itself in ideas. Meanwhile a third conception of the real keeps thrusting itself upon the other two--the view, namely, that body in both senses is a fiction of thought, and that the mere present feeling is alone the real.
Body as ‘parcel of matter’ without essence. 94. Where Locke is insisting on the opposition between the real essence and any essence that can be known, the former is generally ascribed either to a ‘particular being’ or to a ‘parcel of matter.’ The passage which brings the opposition into the strongest relief is perhaps the following:--‘I would ask any one, what is sufficient to make an essential difference in nature between any two particular beings, without any regard had to some abstract idea, which is looked upon as the essence and standard of a species? All such patterns and standards being quite laid aside, particular beings, considered barely in themselves, will be found to have all their qualities equally essential; and everything, in each individual, will be essential to it, or, which is more, nothing at all. For though it may be reasonable to ask whether obeying the magnet be essential to iron; yet I think it is very improper and insignificant to ask whether it be essential to the particular parcel of matter I cut my pen with, without considering it under the name _iron_, or as being of a certain species.’ (Book III. chap. vi. sec. 5.) [1] Here, it will be seen, the exclusion of the abstract idea from reality carries with it the exclusion of that ‘standard made by nature,’ which according to the passages already quoted, is the ‘thing itself from which the abstract idea is taken, and from which, if correctly taken, it derives reality. This exclusion, again, means nothing else than the disappearance from ‘nature’ (which with Locke is interchangeable with ‘reality’) of all essential difference. There remain, however, as the ‘real,’ ‘particular beings,’ or ‘individuals,’ or ‘parcels of matter.’ In each of these, ‘considered barely in itself, everything will be essential to it, or, which is more, nothing at all.’
Text from Project Gutenberg, public domain in the United States.