We have further to note that, while his Continental rivals were mathematicians, our English philosopher never went deeply into mathematics, but was by calling a physician. In this he resembles Aristotle and Sextus Empiricus among the Greeks; and so it is quite in order that, with the same sort of training, he should
adopt Aristotle's method of experience as against Platonic transcendentalism, and the sceptical relativism of Sextus as against the dogmatism of the schools.
Locke begins his essay with a vigorous polemic against the doctrine of Innate Ideas. The word "idea," as he uses it, is ambiguous, serving to denote perceptions, notions, and propositions; but this confusion is of no practical importance, his object being to show that all our knowledge originates in experience; whereas the reigning belief was that at least the first principles of knowledge had a more authoritative, if not a mystical, source. Hobbes had been beforehand with him in deriving every kind of knowledge from experience, but had been content to assume his case; whereas Locke supports his by a formidable array of proofs. The gist of his argument is that intellectual and moral principles supposed to be recognised by all mankind from their infancy are admitted only by some, and by those only as the result of teaching.
As we saw, the whole inquiry began with questions about religion and morality; and it is precisely in reference to the alleged universality and innateness of the belief in God and the moral law that Locke is most successful. And the more modern anthropology teaches us about primitive man, the stronger becomes the case against the transcendental side in the controversy. Where his analysis breaks down is in dealing with the difficult and important ideas of Space, Time, Substance, and Causality—with the fatal result that such questions as, How is experience itself possible? or, How from a partial experience can we draw universal and necessary conclusions? find no place in his theory of knowledge. Of course, his contemporaries are open to the same
criticism—nor, indeed, had the time come even for the statement of such problems. Meanwhile, the facility with which the founder of epistemology accepts fallacies whence Spinoza had already found his way out shows how little he was master of his means. According to Locke, it is "a certain and evident truth that there is an eternal, most powerful, and most knowing being, which whether anyone will please to call God it matters not." On examination the proof appears to involve two unproved assumptions. The first is that nothing can begin to exist without a cause. The second is that effects must resemble their causes. And from these it is inferred that an all-powerful being must have existed from all eternity. The alternative is overlooked that a succession of more limited beings would answer the purpose equally well, while it would also be more consistent with our experience. But a far more fatal objection to Locke's theism results from his second assumption. This, although not explicitly stated, is involved in the assertion that for knowledge such as we possess to originate from things without knowledge is impossible. For, on the same principle, matter must have been made by something material, pain by something that is pained, and evil by something that is evil. It would not even be going too far to say that by this logic I myself must have existed from all eternity; for to say that I was created by a not-myself would be to say that something may come from nothing.
We have seen how Locke refused toleration to atheists on the ground that their denial of a divine lawgiver and judge destroys the basis of morality. He did not, like Spinoza, believe that morality is of the nature of things. For him it is constituted by the will of God. Possibly, if pressed, he might have explained
that what atheism denies is not the rule of right, but the sanction of that rule, the fear of supernatural retribution. Yet being, like Spinoza and Leibniz, a determinist, he should have seen that a creator who sets in motion the train of causes and effects necessarily resulting in what we call good or bad human actions has the same responsibility for those actions as if he had committed them himself. To reward one of his passive agents and to punish another would be grossly unjust and at the same time perfectly useless. But how do we know that he will, on any theory of volition, reward the good and punish the bad? "Because we have his word for it." And how do we know that he will keep his word? "Because he is all-good." But that, on Locke's principles, is pure assumption; and God, being quite sure that he has no retribution to fear, must be even more irresponsible than the atheist.
The principle that nothing can come from nothing, so far from proving theism, leads logically either to pantheism or to a much more thorough monadism than the system of Leibniz. And, metaphysics apart, it conflicts with a leading doctrine of the essay—that is the fundamental distinction between the primary and the secondary qualities of matter. We think of bodies as in themselves extended, resisting and mobile, but not in themselves as coloured, sonorous, odorous, hot, cold, or sapid. They cause our special sensations, but cause them by an unknown power. Again we perceive—or think we perceive—both primary and secondary qualities in close union as properties of a single object, and this object in which they jointly inhere is called a substance. And to the question, What is substance? Locke admits that he has no answer except something we know not what. He has returned to the agnostic standpoint of the
Cyrenaic school. This something, for aught we know, might have created the world.
Continental historians regard the whole rationalistic movement of the eighteenth century, or what in Germany is called the Enlightenment (Aufklärung), as having been started by Locke. But the sort of arguments that he adduces for the existence of a God prove that in theology at least his rationalism had rather narrow limits. Both his theism and his acceptance of Christianity on the evidence of prophecy and miracles show no advance on medieval logic. In this respect Spinoza and Bayle (1622-1709) were far more in line with the modern movement. Still, assuming scripture as an authoritative revelation, Locke shows that, rationally interpreted, it yields much less support to dogmatic orthodoxy than English Churchmen supposed. And whatever may have been the letter of his religious teaching, there can be little doubt that the English Deists, Toland, Shaftesbury, and Anthony Collins, represented its true spirit more faithfully than the philosopher himself.