Inference a transition from an object perceived or remembered to one that is not so.
284. This passage points out the way which Hume’s doctrine of causation was to follow. That in any case ‘the mind should go beyond a present feeling, either to discover the real existence or the relations of objects’ other than present feelings, was what he could not consistently admit. In the judgment of causation, however, it seems to do so. ‘From the existence or action of one object,’ seen or remembered, it seems to be assured of the existence or action of another, not seen or remembered, on the ground of a necessary connection between the two. [1] It is such assurance that is reckoned to constitute reasoning in the distinctive sense of the term, as different at once from the analysis of complex ideas and the simple succession of ideas—such reasoning as, in the language of a later philosophy, can yield synthetic propositions. What Hume has to do, then, is to explain this ‘assurance’ away by showing that it is not essentially different from that judgment of relation in time and place which, because the related objects are ‘present to the senses along with the relation,’ is called ‘perception rather than reasoning,’ and to which no ‘exercise of the thought’ is necessary, but a ‘mere passive admission of impressions through the organs of sensation.’ Nor, for the assimilation of reasoning to perception, is anything further needed than a reference to the connection of ideas with impressions and of the ideas of imagination with those of memory, as originally stated by Hume. When both of the objects compared are present to the senses, we call the comparison perception; when neither, or only one, is so present, we call it reasoning. But the difference between the object that is present to sense, and that which is not, is merely the difference between impression and idea, which again is merely the difference between the more and the less lively feeling. [2] To feeling, whether with more or with less vivacity, every object, whether of perception or reasoning, must alike be present. Is it then a sufficient account of the matter, according to Hume, to say that when we are conscious of contiguity and succession between objects of which both are impressions we call it perception; but that when both objects are ideas, or one an impression and the other an idea, we call it reasoning? Not quite so. Suppose that I ‘have seen that species of object we call flame, and have afterwards felt that species of sensation we call heat.’ If I afterwards remembered the succession of the feeling upon the sight, both objects (according to Hume’s original usage of terms [3]) would be ideas as distinct from the impressions; or, if upon seeing the flame I remembered the previous experience of heat, one object would be an idea; but we should not reckon it a case of reasoning. ‘In all cases wherein we reason concerning objects, there is only one either perceived or remembered, and the other is supplied in conformity to our past experience’—supplied by the only other faculty than memory that can ‘supply an idea,’ viz. imagination. [4]
[1] Pp. 376, 384. [Book I, part III., secs. II. and IV.]
[2] Pp. 327, 375. [Book I, part I., sec. VII. and part III., sec. III.]
[3] Above, par. 195.
[4] Pp. 384, 388. [Book I, part III., secs. IV. and V.]
Relation of cause and effect the same as this transition.
285. This being the only account of ‘inference from the known to the unknown,’ which Hume could consistently admit, his view of the relation of cause and effect must be adjusted to it. It could not be other than a relation either between impression and impression, or between impression and idea, or between idea and idea; and all these relations are equally between feelings that we experience. Thus, instead of being the ‘objective basis’ on which inference from the known to the unknown rests, it is itself the inference; or, more properly, it and the inference alike disappear into a particular sort of transition from feeling to feeling. The problem, then, is to account for its seeming to be other than this. ‘There is nothing in any objects to persuade us that they are always remote or always contiguous; and when from experience and observation we discover that the relation in this particular is invariable, we always conclude that there is some secret cause which separates or unites them’. [1] It would seem, then, that the relation of cause and effect is something which we infer from experience, from the connection of impressions and ideas, but which is not itself impression or idea. And it would seem further, that, as we infer such an unexperienced relation, so likewise we make inferences from it. In regard to identity ‘we readily suppose an object may continue individually the same, though several times absent from and present to the senses; and ascribe to it an identity, notwithstanding the interruption of the perception, whenever we conclude that if we had kept our hand or eye constantly upon it, it would have conveyed an invariable and uninterrupted perception. But this conclusion beyond the impressions of our senses can be founded only on the connection of cause and effect; nor can we otherwise have any security that the object is not changed upon us, however much the new object may resemble that which was formerly present to the senses.’
[1] P. 376. [Book I, part III., sec. II.]
Yet seems other than this. How this appearance is to be explained.