or folly, for men to quit and renounce their former tenets presently upon the offer of an argument which they cannot immediately answer and show the insufficiency of; it would, methinks, become all men to maintain peace and the common offices of humanity and friendship in the diversity of opinions, since we cannot reasonably expect that any one should readily and obsequiously quit his own opinion, and embrace ours with a blind resignation to an authority which the understanding of man acknowledges not. For, however it may often mistake, it can own no other guide but reason, nor blindly submit to the will and dictates of another. If he you would bring over to your sentiments be one that examines before he assents, you must give him leave at his leisure to go over the account again, and, recalling what is out of his mind, examine the particulars, to see on which side the advantage lies; and if he will not think over arguments of weight enough to engage him anew in so much pains, it is but what we do often ourselves in the like case; and we should take it amiss if others should prescribe to us what points we should study: and if he be one who wishes to take his opinions upon trust, how can we imagine that he should renounce those tenets which time and custom have so settled in his mind that he thinks them self-evident, and of an unquestionable certainty; or which he takes to be impressions he has received from God himself, or from men sent by him? How can we expect, I say, that opinions thus settled should be given up to the arguments or authority of a stranger or adversary? especially if there be any suspicion of interest or design, as there never fails to be where men find themselves ill-treated. We should do well to commiserate our mutual ignorance, and endeavour to remove it in all the gentle and fair ways of information, and not instantly treat others ill as obstinate and perverse because they will not renounce their own and receive our opinions, or at least those we would force upon them, when it is more than probable that we are no less obstinate in not embracing some of theirs. For where is the man that has uncontestable evidence of the truth of all that he holds, or of the falsehood of all he condemns; or can say, that he has examined to the bottom all his own or other men's opinions? The necessity of believing without knowledge, nay often upon very slight grounds, in this fleeting state of action and blindness we are in, should make us more busy and careful to inform ourselves than to restrain others…. There is reason to think, that if men were better instructed themselves, they would be less imposing on others.'1
I have dealt hitherto only with the latest chapters of the Essay, where Locke is drawing the moral from his earlier theoretical investigation of the nature and limitations of human knowledge. It is time now to examine what he has to say on this more purely philosophical subject.
Locke is, as a rule, contemptuous of metaphysics. Apropos of some speculation of Leibniz's, he writes to a friend: 'You and I have had enough of this kind of fiddling.' The conception of substance, which was dominant in the metaphysics of his time, he considers vague and not useful, but he does not venture to reject it wholly. He allows the validity of metaphysical arguments for the existence of God, but he does not dwell on them, and seems somewhat uncomfortable about them. Whenever he is expressing new ideas, and
not merely repeating what is traditional, he thinks in terms of concrete detail rather than of large abstractions. His philosophy is piecemeal, like scientific work, not statuesque and all of a piece, like the great Continental systems of the seventeenth century.
Locke may be regarded as the founder of empiricism, which is the doctrine that all our knowledge (with the possible exception of logic and mathematics) is derived from experience. Accordingly the first book of the Essay is concerned in arguing, as against Plato, Descartes, and the scholastics, that there are no innate ideas or principles. In the second book