[1] P. 394. [Book I, part III., sec. VII.]
[2] P. 370. [Book I, part II., sec. VI.]
[3] P. 395. [Book I, part III., sec. II.]
[4] P. 398 [Book I, part III., sec. VII.]. Cf. above, par. 170, for the corresponding view in Berkeley.
It results that necessary connection is an impression of reflection, i.e., a propensity to the transition described.
292. Thus it appears that in order to the conclusion that any particular cause must have any particular effect, there is needed first the presence of an impression, and secondly the joint action of those two ‘principles of union among ideas,’ resemblance and contiguity. In virtue of the former principle the given impression calls up the image of a like impression previously experienced, which again in virtue of the latter calls up the image of its usual attendant, and the liveliness of the given impression so communicates itself to the recalled ideas as to constitute belief in their existence. If this is the true account of the matter, the question as to the nature of necessary connexion has answered itself. ‘The necessary connexion betwixt causes and effects is the foundation of our inference from one to the other. The foundation of the inference is the transition arising from the accustomed union. These are therefore the same’. [1] We may thus understand how it is that there seems to be an idea of such connexion to which no impression of the senses, or (to use an equivalent phrase of Hume’s) no ‘quality in objects’ corresponds. If the first presentation of two objects, of which one is cause, the other effect, (i.e. of which we afterwards come to consider one the cause, the other the effect) gives no idea of a connexion between them, as it clearly does not, neither can it do so however often repeated. It would not do so, unless the repetition ‘either discovered or produced something new’ in the objects; and it does neither. But it does ‘produce a new impression in the mind.’ After observing a ‘constant conjunction of the objects, and an uninterrupted resemblance of their relations of contiguity and succession, we immediately feel a determination of the mind to pass from one of the objects to its usual attendant, and to conceive it in a stronger light on account of that relation.’ It is of this ‘internal impression,’ this ‘propensity which custom produces,’ that the idea of necessary connexion is the copy. [2]
[1] P. 460. [Book I, part III., sec. XIV.]
[2] Pp. 457-460. [Book I, part III., sec. XIV.]
The transition not to anything beyond sense.
293. The sequence of ideas, which this propensity determines, clearly does not involve any inference ‘beyond sense,’ ‘from the known to the unknown,’ ‘from instances of which we have had experience, to those of which we have had none,’ any more than does any other ‘recurrence of an idea’—which, as we have seen, merely means, according to Hume, the return of a feeling at a lower level of intensity after it has been felt at a higher. The idea which we speak of as an inferred cause or effect is only an ‘instance of which we have no experience’ in the sense of being numerically different from the similar ideas, whose previous constant association with an impression like the given one, determines the ‘inference;’ but in the same sense the ‘impression’ which I now feel on putting my hand to the fire is different from the impressions previously felt under the same circumstances, and I do not for that reason speak of this impression as an instance of which I have had no experience. Thus Hume, though retaining the received phraseology in reference to the ‘conclusion from any particular cause to any particular effect’—phraseology which implies that prior to the inference the object inferred is in some sense unknown or unexperienced—yet deprives it of meaning by a doctrine which makes inference, as he himself puts it, ‘a species of sensation,’ ‘an unintelligible instinct of our souls,’ ‘more properly an act of the sensitive than of the cogitative part of our natures’ [1]—which in fact leaves no ‘part of our natures’ to be cogitative at all.