If, therefore, a present perception leads us to assert the existence of some other, this can only be interpreted as meaning that in some natural, i.e. psychological, manner the idea of this other perception is excited, and that the idea is viewed by the mind in some peculiar fashion. The natural link of connexion Hume finds in the similarities presented by experience. One fact or perception is discovered by experience to be uniformly or generally accompanied by another, and its occurrence therefore naturally excites the idea of that other. But when an idea is so roused up by a present impression, and when this idea, being a consequence of memory, has in itself a certain vivacity or liveliness, we regard it with a peculiar indefinable feeling, and in this feeling consists the immense difference between mere imagination and belief. The mind is led easily and rapidly from the present impression to the ideas of impressions found by experience to be the usual accompaniments of the present fact. The ease and rapidity of the mental transition is the sole ground for the supposed necessity of the causal connexion between portions of experience. The idea of necessity is not intuitively obvious; the ideas of cause and effect are correlative in our minds, but only as a result of experience. Hobbes and Locke were wrong in saying that the mind must find in the relation the idea of Power. We mistake the subjective transition resting upon custom or past experience for an objective connexion independent of special feelings. All reasoning about matters of fact is therefore a species of feeling, and belongs to the sensitive rather than to the cogitative side of our nature. It should be noted that this theory of Causation entirely denies the doctrine of Uniformity in Nature, so far as the human mind is concerned. All alleged uniformity is reduced to observed similarity of process. The idea is a mere convention, product of inaccurate thinking and custom.
While it is evident that some such conclusion must follow from the attempt to regard the cognitive consciousness as made up of disconnected feelings, it is equally clear, not only that the result is self-contradictory, but that it involves certain assumptions not in any way deducible from the fundamental view with which Hume starts. For in the problem of real cognition he is brought face to face with the characteristic feature of knowledge, distinction of self from matters known, and reference of transitory states to permanent objects or relations. Deferring his criticism of the significance of self and object, Hume yet makes use of both to aid his explanation of the belief attaching to reality. The reference of an idea to past experience has no meaning, unless we assume an identity in the object referred to. For a past impression is purely transitory, and, as Hume occasionally points out, can have no connexion of fact with the present consciousness. His exposition has thus a certain plausibility, which would not belong to it had the final view of the permanent object been already given.
The final problem of Hume’s theory of knowledge, the discussion of the real significance of the two factors of cognition, self and external things, is handled in the Treatise with great fulness and dialectical subtlety.
As in the case of the previous problem, it is unnecessary to follow the steps of his analysis, which are, for the most part, attempts to substitute qualities of feeling for the relations of thought which appear to be involved. The results follow with the utmost ease from his original postulate. If there is The self in cognition. nothing in conscious experience save what observation can disclose, while each act of observation is itself an isolated feeling (an impression or idea), it is manifest that a permanent identical thing can never be an object of experience. Whatever permanence or identity is ascribed to an impression or idea is the result of association, is one of those “propensities to feign” which are due to natural connexions among ideas. We regard as successive presentations of one thing the resembling feelings which are experienced in succession. Identity, then, whether of self or object, there is none, and the supposition of objects, distinct from impressions, is but a further consequence of our “propensity to feign.” Hume’s explanation of the belief in external things by reference to association is well deserving of careful study and of comparison with the more recent analysis of the same problem by J. S. Mill.
The weak points in Hume’s empiricism are so admirably realized by the author himself that it is only fair to quote his own summary in the Appendix to the Treatise. He confesses that, in confining all cognition to single perceptions and supplying no purely intellectual faculty for modifying,Negative result of Hume’s treatise. recording and classifying their results, he has destroyed real knowledge altogether:
“If perceptions are distinct existences, they form a whole only by being connected together. But no connexions among distinct existences are ever discoverable by human understanding. We only feel a connexion or determination of the thought to pass from one object to another. It follows, therefore, that the thought alone feels personal identity, when, reflecting on the train of past perceptions that compose a mind, the ideas of them are felt to be connected together and naturally introduce each other.
“However extraordinary this conclusion may seem, it need not surprise us. Modern philosophers seem inclined to think that personal identity arises from consciousness, and consciousness is nothing but a reflected thought or perception. The present philosophy, therefore, has a promising aspect. But all my hopes vanish when I come to explain the principles that unite our successive perceptions in our thought or consciousness. I cannot discover any theory which gives me satisfaction on this head. . . .
“In short, there are two principles which I cannot render consistent, nor is it in my power to renounce either of them; viz. that all our distinct perceptions are distinct existences, and that the mind never perceives any real connexion among distinct existences. Did our perceptions either inhere in something simple or individual, or did the mind perceive some real connexion among them, there would be no difficulty in the case” (ii. 551).
The closing sentences of this passage may be regarded as pointing to the very essence of the Kantian attempt at solution of the problem of knowledge. Hume sees distinctly that if conscious experience be taken as containing only isolated states, no progress in explanation of cognition is possible, and that the only hope of further development is to be looked for in a radical change in our mode of conceiving experience. The work of the critical philosophy is the introduction of this new mode of regarding experience, a mode which, in the technical language of philosophers, has received the title of transcendental as opposed to the psychological method followed by Locke and Hume. It is because Kant alone perceived the full significance of the change required in order to meet the difficulties of the empirical theory that we regard his system as the only sequel to that of Hume. The writers of the Scottish school, Reid in particular, did undoubtedly indicate some of the weaknesses in Hume’s fundamental conception, and their attempts to show that the isolated feeling cannot be taken as the ultimate and primary unit of cognitive experience are efforts in the right direction. But the question of knowledge was never generalized by them, and their reply to Hume, therefore, remains partial and inadequate, while its effect is weakened by the uncritical assumption of principles which is a characteristic feature of their writings.
The results of Hume’s theoretical analysis are applied by him to
the problems of practical philosophy and religion. For the first
of these the reader is referred to the article Ethics, where
Hume’s views are placed in relation to those of his predecessors
in the same field of inquiry. His position, as
Theology
and ethics.
regards the second, is very noteworthy. As before said, his
metaphysic contains in abstracto the principles which were at that
time being employed, uncritically, alike by the deists and by their
antagonists. There can be no doubt that Hume has continually in
mind the theological questions then current, and that he was fully
aware of the mode in which his analysis of knowledge might be
applied to them. A few of the less important of his criticisms, such
as the argument on miracles, became then and have since remained
public property and matter of general discussion. But the full
significance of his work on the theological side was not at the time
perceived, and justice has barely been done to the admirable manner
in which he reduced the theological disputes of the century to their
ultimate elements. The importance of the Dialogues on Natural
Religion, as a contribution to the criticism of theological ideas and
methods, can hardly be over-estimated. A brief survey of its contents
will be sufficient to show its general nature and its relations to such
works as Clarke’s Demonstration and Butler’s Analogy. The Dialogues
introduce three interlocutors, Demea, Cleanthes and Philo, who
represent three distinct orders of theological opinion. The first is
the type of a certain a priori view, then regarded as the safest bulwark
against infidelity, of which the main tenets were that the being of
God was capable of a priori proof, and that, owing to the finitude of
our faculties, the attributes and modes of operation of deity were
absolutely incomprehensible. The second is the typical deist of
Locke’s school, improved as regards his philosophy, and holding that
the only possible proof of God’s existence was a posteriori, from
design, and that such proof was, on the whole, sufficient. The third
is the type of completed empiricism or scepticism, holding that no
argument, either from reason or experience, can transcend experience,
and consequently that no proof of God’s existence is at all possible.
The views of the first and second are played off against one another,
and criticized by the third with great literary skill and effect.
Cleanthes, who maintains that the doctrine of the incomprehensibility
of God is hardly distinguishable from atheism, is compelled
by the arguments of Philo to reduce to a minimum the conclusion
capable of being inferred from experience as regards the existence
of God. For Philo lays stress upon the weakness of the analogical
argument, points out that the demand for an ultimate cause is no
more satisfied by thought than by nature itself, shows that the
argument from design cannot warrant the inference of a perfect or
infinite or even of a single deity, and finally, carrying out his principles
to the full extent, maintains that, as we have no experience of the
origin of the world, no argument from experience can carry us to its
origin, and that the apparent marks of design in the structure of
animals are only results from the conditions of their actual existence.
So far as argument from nature is concerned, a total suspension of
judgment is our only reasonable resource. Nor does the a priori
argument in any of its forms fare better, for reason can never demonstrate
a matter of fact, and, unless we know that the world had a
beginning in time, we cannot insist that it must have had a cause.
Demea, who is willing to give up his abstract proof, brings forward
the ordinary theological topic, man’s consciousness of his own
imperfection, misery and dependent condition. Nature is throughout
