manner of mathematics. He did not believe that mathematics, with its applications to physics, was itself the highest knowledge. He sought rather to formulate a logic that should be as exact as mathematics, but more fundamental and universal; thus affording a basis for the demonstration of the higher truths concerning God and the soul. The "Discourse on Method" is a record of the author's profound regard for mathematics and of his own search for a like certainty in philosophy.

6

But Hobbes (1588-1679) was a follower of Galileo in a different sense. He proposed not so much to imitate mathematics as to adopt and extend it. He represents that idea which La Place so eloquently proclaimed a century later, and which the work of Newton seemed so nearly to realize, the idea of a universal mechanism, in which the laws of bodily motion should apply even to the origins of nature and to man. It was hoped thus to bring it about that all things should be as demonstrably known, and as certainly predictable, as the velocities and orbits of the planets. To this end the author of "The Leviathan" regards both man and society, the little man and the giant composite man, as simply delicate and complicated mechanisms, moved by an impulse of self-seeking.

These, then, are the three forms in which the science of the Renaissance as embodied in Galileo is communicated to modern philosophy. Bacon, Descartes, and Hobbes became in turn the sources of the new tendencies that make up the philosophy of the seventeenth and eighteenth centuries. The empiricism of Bacon was renewed in Locke, who applied "the plain historical method" to the study of the human mind; continued by Berkeley, who reduced even being to perception ("esse est, percipi"); was brought to a sceptical crisis in Hume;10 but persisted as the national philosophy of England. The rationalism of Descartes afforded a basis for the great metaphysical systems of Continental philosophy, for the monism of Spinoza and the pluralism of Leibnitz; was degraded to a mere formalism and dogmatism in Wolff; but nevertheless persisted in the new idealistic 8 H. C., xxxvii, 9.

H. C., xxxiv, 5. H. C., xxxiv, 323.
H. C., xxxvii, 201.

10 H. C., xxxvii, 305.

German philosophy which was inspired by Kant. The physical philosophy of Hobbes, mingled with similar elements drawn from the philosophies of Locke and Descartes, developed into the French materialistic movement which attended the outbreak of the Revolution, and remains the model for all philosophers who seek to make a metaphysics out of physics. The forms which these three tendencies assumed during the eighteenth century, and especially their excessive emphasis on facts and necessities, provoked the great reaction which bore fruit in the following century, but which was already anticipated in Pascal's philosophy of faith," in Rousseau's philosophy of feeling," and in Lessing's philosophy of development."

n H. C., xlviii. 12 H. C., xxxiv, 167.

13 H. C., xxxii, 195

I

IV. INTRODUCTION TO KANT

BY PROFESSOR RALPH BARTON PERRY

T IS generally admitted that Kant is one of the great epoch-making philosophers, like Socrates and Descartes.

There are two things that are universally true of intellectual epoch-makers: first, they embody in themselves certain general tendencies of their age, which are usually due to a reaction against the more pronounced tendencies of the previous age; second, their thought is peculiarly germinal, and among their followers assumes a maturer form, in which the originators would scarcely recognize it as their own. Let us consider these two aspects of the philosophy of Kant.

REVOLT AGAINST PURE EMPIRICISM AND PURE RATIONALISM

From among the pronounced tendencies of the seventeenth and eighteenth centuries I shall select two for special emphasis. In the first place, it was characteristic of these two centuries to isolate and over-emphasize either one or the other of the two great sources of human knowledge, sense-perception or reason. Locke and his followers attempted to convert reason into a mere echo of sense; while for Descartes and his followers, sense was always viewed with suspicion as confusing the intellect, or as supplying only an inferior sort of knowledge which must yield precedence to "rational science." Extreme sensationalism or empiricism seemed to have reached an impasse in Hume; while rationalism degenerated into formalism and wordmaking in Wolff. Thus Kant's greatest work, the "Critique of Pure Reason" (1789), was an attempt to correct these extreme views by making the necessary provision for both sense-perception and reason. Perception without conception, he said, is blind; while conception without perception

is empty. Kant's critique was aimed first at excessive emphasis on sense-perception. He showed that the bare sequence of sense-impressions can never yield the connections, necessities, unities, laws, etc., which are required for science. The intellect must supply these itself. They constitute what Kant called "categories," the instruments which the mind must use when it works in that peculiar way which is called knowing. But it follows that they are not by themselves sufficient for knowledge. They cannot themselves be known in the ordinary way because they are what one knows with. And since they are instruments, it follows that they require some material to work upon; they cannot spin knowledge out of nothing. Hence the data of sense are indispensable also. In short, to know is to systematize, by the instrumentalities native to the mind, the content conveyed by the senses. This is the Kant of the first Critique, the Kant of technical philosophy who numbers many faithful devotees among the thinkers of to-day.

REASSERTION OF THE SPIRITUAL

A second and more general tendency of seventeenth and eighteenth century philosophy was its comparative neglect of what are vaguely called the "spiritual" demands. These centuries themselves may be regarded as a reaction against what was thought to be the excessive anthropomorphism of earlier times. Man had erred by reading himself into his world; now he was to view it impersonally and dispassionately. He might prefer to record the findings of perception, or the necessities of reason, but in either case he was to repress his own interests and yearnings. Of course at the time it was confidently expected that morality and religion would in this way be served best. possibility of a "natural religion," dogma, a rational morality without monstrable theology without either revelation or faith. But gradually there developed a sense of failure. Man had left himself too much out of it, and felt homeless and unprotected. Early in the seventeenth century Pascal had announced the religious bankruptcy of the mathematical

Men believed in the without mystery or authority, and a de

rationalism of Descartes. Natural religion was readily converted into atheism by Hume. The most vigorous and stirring protest against the whole spirit of the age was made by Rousseau, who urged men to trust their feelings, make allowance for the claims of the heart, and return to the elemental and spontaneous in human nature. The same note was caught up by Jacobi and Herder. Finally Lessing, in his "Education of the Human Race" (1780), turned the attention of philosophy to the history of culture, to the significance of human life in its historical unfolding. It is a strange paradox that Immanuel Kant, valetudinarian and pedant that he was, should have represented this rising revolt of sentiment and faith. But such was the fact. Let us, then, view him in this light.

THE KANTIAN REVOLUTION

One of the most famous of Kant's remarks was that he proposed to effect a Copernican Revolution in thought. As 'Copernicus had established a new center for the planetary system, so he proposed to establish a new center for knowledge. This new center was to be the mind itself. The errors of the earlier period had been largely due, he thought, to the attempt to make knowledge center in the object, it being expected that the mind should reflect, either by perception or reason, the nature of an outward and independently existing thing. This method leads inevitably, said Kant, either to scepticism or to what is just as bad for philosophical purposes, dogmatism. The new way is to expect 'that the object shall conform to the mind. Thus nature, which in the earlier view was construed as an external order by which the mind is affected, or which the mind is somehow to reproduce by its own ratiocination, is now construed as the original creation of the mind. It owes all of its arrangements and connections, even its very distribution in space and time, to the constitution of the knower. The mind imposes its conditions on the object, and thus gets out of nature what it has already put into it. The bearing of 1 See Pascal's "Thoughts," Harvard Classics, xlviii, 33f.; 414f. H. C., xxxii, 195.