(Copyright B. P. C.)
Kant grew up among the Pietists, a school which played much the same part in Germany that the Methodists and the Evangelicals played in England; indeed, it was from them that John Wesley received his final inspiration. The Königsberg student came in time to discard their theology while retaining the stern Puritan morality with which it was wedded, and even, Rationalist as he became, some of their mystical religiosity. What drew him away to philosophy seems to have been first the study of classical philology and then physical science, especially as presented to him in Newton's works. And so the young man's first ambition, after settling down as a University teacher at Königsberg, was to extend the Newtonian method still further by explaining, on mechanical principles, the origin and constitution of that celestial system whose movements Newton had reduced to law, but whose beginning he had left unaccounted for except by—what was not science—the direct fiat of omnipotence.
Kant offered a brilliant solution of the problem in his Natural History of the Heavens (1755), a work embodying the celebrated nebular hypothesis rediscovered forty years later by Laplace. It has been well observed that great philosophers are mostly, if not always, what at Oxford and Cambridge would be called "double-firsts"—that is, apart from their philosophy, they have done first-class work in some special line of investigation, as Descartes by creating analytical geometry, Spinoza by applying Biblical criticisms to theology, Leibniz by discovering the differential calculus, Locke by his theory of constitutional government, Berkeley by his theory of vision, Hume by his contributions to history and political economy. Kant's cosmogony may have been premature and mistaken in its details; but his idea of the heavenly bodies as having originated from the condensation of diffused gaseous matter still holds its
ground; and although the more general idea of natural evolution as opposed to supernatural creation is not modern but Greek, to have revived and reapplied it on so great a scale is a service of extraordinary merit.
The next great event in Kant's intellectual career is his rejection of Continental apriorism in metaphysics for the empiricism of the English school, especially as regards the idea of causation. For a few years (1762-1765) Kant accepts Hume's theory that there is nothing in any succession of events or in change generally to prove on grounds of pure reason that there must be more in it than a customary sequence. To believe that anything may happen without a cause does not involve a logical contradiction; and at that time he believed nothing to be known à priori except that the denial of which involves such a contradiction. But on reconsidering the basis of mathematical truth it seemed to him to be something other than the logical laws of Identity and Contradiction. When we say that seven and five are twelve we put something into the predicate that was not affirmed in the subject, and also when we say that a straight line is the shortest distance between two points. Yet the second proposition is as certain as the first, and both are certain in the highest degree, more certain than anything learned from experience, and needing no experience to confirm them.
So much being admitted, we have to recognise a fundamental division of judgments into two classes, analytic and synthetic. Judgments in which the predicate adds nothing to the subject are analytic. When we affirm all matter to be extended, that is an instance of the former, for here we are only making more explicit what was already contained in the notion of matter. On the other hand, when we affirm that all matter is heavy, that is an
instance of the latter or synthetic class, for we can think of matter without thinking that it has weight. Furthermore, this is not only a synthetic judgment, but it is a synthetic judgment à posteriori; for the law of universal gravitation is known only by experience. But there are also synthetic judgments à priori; for, as we have just seen, the fundamental truths of arithmetic and geometry belong to this class, as do also by consequence all the propositions logically deduced from these—that is to say, the whole of mathematical science.