But this distinction he only professes to adopt in order to explain it away.
336. There is a great difference between the meaning which the above passage conveys when read in the light of the accepted logic of science, and that which it conveys when interpreted consistently with the theory in the statement of which it occurs. Whether Hume, in writing as he does of that conclusion from a single experiment, which our observation concerning the connexion of cause and effect enables us to draw, understood himself to be expressing his own theory or merely using the received language provisionally, one cannot be sure; but it is certain that such language can only be justified by those ‘maxims of philosophers’ which it is the purpose or effect of his doctrine to explain away—in particular the maxims that ‘the connexion between all causes and effects is equally necessary and that its seeming uncertainty in some instances proceeds from the secret opposition of contrary causes;’ and that ‘what the vulgar call chance is but a concealed cause’. [1] These maxims represent the notion that the law of causation is objective and universal; that all seeming limitations to it, all ‘probable and contingent matter,’ are the reflections of our ignorance, and exist merely ex parte nostrâ. In other words, they represent the notion of that ‘continued existence distinct from our perceptions,’ which with Hume is a phrase generated by ‘propensities to feign.’ Yet he does not profess to reject them; nay, he handles them as if they were his own, but after a very little of his manipulation they are so ‘translated’ that they would not know themselves. Because philosophers ‘allow that what the vulgar call chance is nothing but a concealed cause,’ ‘probability of causes’ and ‘probability of chances’ may be taken as equivalent. But chance, as ‘merely negation of a cause,’ has been previously explained, on the supposition that causation means a ‘perfect habit of imagination,’ to be the absence of such habit—the state in which imagination is perfectly indifferent in regard to the transition from a given impression to an idea, because the transition has not been repeated often enough to form even the beginning of a habit. Such being mere chance, ‘probability of chances’ means a state of imagination between the perfect indifference and that perfect habit of transition, which is ‘necessary connexion.’ ‘Probability of causes’ is the same thing. Its strength or weakness depends simply on the proportion between the number of experiments (‘each experiment being a kind of chance’) in which A has been found to immediately follow B, and the number of those in which it has not. [2] Mere chance, probability, and causation then are equally states of imagination. The ‘equal necessity of the connexion between all causes and effects’ means not that any ‘law of causation pervades the universe,’ but that, unless the habit of transition between any feelings is ‘full and perfect,’ we do not speak of these feelings as related in the way of cause and effect.
[1] Pp. 429 & 430. [Book I, part III., sec. XII.]
[2] Pp. 424-428, 432-434. [Book I, part III., secs. XI. and XII.]
Laws of nature are unqualified habits of expectation.
337. Interpreted consistently with this doctrine, the passage quoted in the last paragraph but one can only mean that, when a man has arrived at maturity, his experience of the sequence of feelings cannot fail in quantity. He must have had experience enough to form not only a perfect habit of transition from any impression to the idea of its usual attendant, but a habit which would act upon us even in the case of novel events, and lead us after a single experiment or a sequence confidently to expect its recurrence, if only the experience had been uniform. It is because it has not been so, that in many cases the habit of transition is still imperfect, and the sequence of A on B not ‘proven,’ but ‘probable.’ The probability then which affects the imagination of the matured man is of the sort that arises from ‘contrary causes,’ as distinct from ‘imperfect experience.’ This is all that the passage in question can fairly mean. Such ‘probability’ cannot become ‘proof,’ or the ‘imperfect habit,’ perfect, by discovery of any necessary connexion or law of causation, for the perfect habit of transition, the imagination enlivened to the maximum by custom, is the law of causation. The formation of the habit constitutes the law: to discover it would be to discover what does not yet exist. The incompleteness of the habit in certain directions, the limitation of our assurance to certain sequences as distinct from others, must be equally a limitation to the universality of the law. It is impossible then that on the faith of the universality of the law we should seek to extend the range of that assurance which is identical with it. Our ‘observation concerning the connexion of causes and effects’ merely means the sum of our assured expectations, founded on habit, at any given time, and that on the strength of this we should ‘prepare an experiment,’ with a view to assuring ourselves of a universal sequence from a single instance, is as unaccountable as that, given the instance, the assurance should follow.
Experience, according to his account of it, cannot be a parent of knowledge.
338. The case then stands thus. In order to make the required distinction between inference to real existence and the lively suggestion of an idea, Hume has to graft on his theory the alien notion of an objective system, an order of nature, represented by ideas of memory, and on the strength of such a notion to interpret a transition from these ideas to others, because we cannot help making it, as an objective necessity. Of such alien notion and interpretation he avails himself in his definition (understood as he means it to be understood) of cause as a ‘natural relation’. [1] But he had not the boldness of his later disciples. Though he could be inconsistent so far, he could not be inconsistent far enough to make his theory of inference fit the practice of natural philosophers. Bound by his doctrine of ideas as copied from impressions, he can give no account of inferred ideas that shall explain the extension of knowledge beyond the expectation that we shall feel again what we have felt already. It was not till another theory of experience was forthcoming than that given by the philosophers who were most fond of declaring their devotion to it, that the procedure of science could be justified. The old philosophy, we are often truly told, had been barren for want of contact with fact. It sought truth by a process which really consisted in evolving the ‘connotation’ of general names. The new birth came when the mind had learnt to leave the idols of the tribe and cave, and to cleave solely to experience. If the old philosophy, however, was superseded by science, science itself required a new philosophy to answer the question. What constitutes experience? It was in effect to answer this question that Locke and Hume wrote, and it is the condemnation of their doctrine that, according to it, experience is not a possible parent of science. It is not those, we know, who cry ‘Lord, Lord!’ the loudest, that enter into the kingdom of heaven, nor does the strongest assertion of our dependence on experience imply a true insight into its nature. Hume has found acceptance with men of science as the great exponent of the doctrine that there can be no new knowledge without new experience. It has not been noticed that with him such ‘new experience’ could only mean a further repetition of familiar feelings, and that if it means more to his followers, it is only because they have been less faithful than he was to that antithesis between thought and reality which they are not less loud in asserting.
[1] See above, paragraph 317.
His attitude towards doctrine of thinking substance.