Our knowledge under Locke’s fourth category of relations—real existence—includes (a) intuitive perceptions of our own existence; (b) demonstrable certainty of the existence of God; and (c) actual perception of the existence of surrounding things, Real existence. as long as, but only as long as the things are present to sense. “If I doubt all other things, that very doubt makes me perceive my own existence, and will not suffer me to doubt of that” (iv. 9. 3). Faith in the existence of God is virtually with Locke an expression of faith in the principle of active causality in its ultimate universality. Each person knows that he now exists, and is convinced that he had a beginning; with not less intuitive certainty he knows that “nothing can no more produce any real being than it can be equal to two right angles.” His final conclusion is that there must be eternally “a most powerful and most knowing Being, in which, as the origin of all, must be contained all the perfections that can ever after exist,” and out of which can come only what it has already in itself; so that as the cause of my mind, it must be Mind. There is thus causal necessity for Eternal Mind, or what we call “God.” This is cautiously qualified thus in a letter to Anthony Collins, written by Locke a few months before he died: “Though I call the thinking faculty in me ‘mind,’ yet I cannot, because of that name, equal it in anything to that infinite and incomprehensible Being, which, for want of right and distinct conceptions, is called ‘Mind’ also.” But the immanence of God in the things and persons that compose the universal order, with what this implies, is a conception foreign to Locke, whose habitual conception was of an extra-mundane deity, the dominant conception in the 18th century.

Turning from our knowledge of Spirit to our knowledge of Matter, nearly all that one can affirm or deny about “things external is,” according to Locke, not knowledge but venture or presumptive trust. We have, strictly speaking, no “knowledge” Knowledge of the external world. of real beings beyond our own self-conscious existence, the existence of God, and the existence of objects of sense as long as they are actually present to sense. “When I see an external object at a distance, a man for instance, I cannot but be satisfied of his existence while I am looking at him. (Locke might have added that when one only ‘sees a man’ it is merely his visible qualities that are perceived; his other qualities are as little ‘actual present sensations’ as if he were out of the range of sense.) But when the man leaves me alone, I cannot be certain that he still exists.” “There is no necessary connexion between his existence a minute since (when he was present to any sense of sight) and his existence now (when he is absent from all my senses); by a thousand ways he may have ceased to be. I have not that certainty of his continued existence which we call knowledge; though the great likelihood of it puts it past doubt. But this is but probability and not knowledge” (chap. 11, § 9). Accordingly, purely rational science of external Nature is, according to Locke, impossible. All our “interpretations of nature” are inadequate; only reasonable probabilities, not final rational certainties. This boundless region affords at the best probabilities, ultimately grounded on moral faith, all beyond lies within the veil. Such is Locke’s “plain, matter-of-fact” account of the knowledge of the Real that is open to man.

We learn little from Locke as to the rationale of the probabilities on which man thus depends when he deals with the past, the distant or the future. The concluding chapters of the The rationale of probability. fourth book contain wise advice to those whose lives are passed in an ever-changing environment, for avoiding the frequent risk of error in their conclusions, with or without the help of syllogism, the office of which, as a means of discovery, is here critically considered.

Investigation of the foundation of inductive inference was resumed by Hume where Locke left it. With a still humbler view of human reason than Locke’s, Hume proposed as “a subject worthy of curiosity,” to inquire into “the nature of that Locke and Hume. evidence which assures us of any real existence and matter of fact, beyond the present testimony of our senses and the records of our memory; a part of philosophy that has been little cultivated either by the ancients or the moderns.” Hume argues that custom is a sufficient practical explanation of this gradual enlargement of our objective experience, and that no deeper explanation is open to man. All beyond each present transitory “impression” and the stores of memory is therefore reached blindly, through custom or habitual association. Associative tendency, individual or inherited, has since been the favourite constructive factor of human experience in Empirical Philosophy. This factor is not prominent in Locke’s Essay. A short chapter on “association of ideas” was added to the second book in the fourth edition. And the tendency to associate is there presented, not as the fundamental factor of human knowledge, but as a chief cause of human error.

Kant’s critical analysis of pure reason is more foreign to Locke than the attempts of 18th- and 19th-century associationists and evolutionists to explain experience and science. Kant’s aim was to show the necessary rational constitution of experience. Locke and Kant. Locke’s design was less profound. It was his distinction to present to the modern world, in his own “historical plain method,” perhaps the largest assortment ever made by any individual of facts characteristic of human understanding. Criticism of the presuppositions implied in those facts—by Kant and his successors, and in Britain more unpretentiously by Reid, all under the stimulus of Hume’s sceptical criticism—has employed philosophers since the author of the Essay on Human Understanding collected materials that raised deeper philosophical problems than he tried to solve. Locke’s mission was to initiate modern criticism of the foundation and limits of our knowledge. Hume negatively, and the German and Scottish schools constructively, continued what it was Locke’s glory to have begun.

Bibliography.—The Essay concerning Human Understanding has passed through more editions than any classic in modern philosophical literature. Before the middle of the 18th century it had reached thirteen, and it has now passed through some forty editions, besides being translated into Latin, French, Dutch, German and modern Greek. There are also several abridgments. In addition to those criticisms which appeared when Locke was alive, among the most important are Leibnitz’s Nouveaux Essais sur l’entendement humain—written about 1700 and published in 1765, in which each chapter of the Essay of Locke is examined in a corresponding chapter by Leibnitz; Cousin’s “École sensualiste: système de Locke,” in his Histoire de la philosophie au XVIIIe siècle (1829); and the criticisms in T. H. Green’s Introduction to the Philosophical Works of Hume (1874). The Essay, with Prolegomena, biographical, critical and historical, edited by Professor Campbell Fraser and published by the Oxford Clarendon Press in 1894, is the only annotated edition, unless the Nouveaux Essais of Leibnitz may be reduced to this category.

The Letters on Toleration, Thoughts on Education and The Reasonableness of Christianity have also gone through many editions, and been translated into different languages.

The first collected edition of Locke’s Works was in 1714, in three folio volumes. The best is that by Bishop Law, in four quartos (1777). The one most commonly known is in ten volumes (1812).

The Éloge of Jean le Clerc (Bibliothèque choisie, 1705) has been the basis of the memoirs of Locke prefixed to the successive editions of his Works, or contained in biographical dictionaries. In 1829 a Life of Locke (2nd ed. in two volumes, with considerable additions, 1830), was produced by Peter, 7th Baron King, a descendant of Locke’s cousin, Anne Locke. This adds a good deal to what was previously known, as Lord King was able to draw from the mass of correspondence, journals and commonplace books of Locke in his possession. In the same year Dr Thomas Foster published some interesting letters from Locke to Benjamin Furly. The most copious account of the life is contained in the two volumes by H. R. Fox-Bourne (1876), the results of laborious research among the Shaftesbury Papers, Locke MSS. in the British Museum, the Public Record Office, the Lambeth, Christ Church and Bodleian libraries, and in the Remonstrants’ library at Amsterdam. Monographs on Locke by T. H. Fowler in 1880, in “English Men of Letters,” and by Fraser, in 1890, in Blackwood’s “Philosophical Classics” may be mentioned; also addresses by Sir F. Pollock and Fraser at the bicentenary commemoration by the British Academy of Locke’s death, published in the Proceedings of the Academy (1904). See also C. Bastide, John Locke; ses théories politiques et leur influence en Angleterre (Paris, 1907); H. Ollion, La Philosophie générale de J. L. (1909).

(A. C. F.)