CHAPTER III.
The Ethics of Kant.
1.—The Criticism of Knowledge.
Kant took the same ground as the Materialists. He recognised that the world outside of us is real, and that the starting-point of all knowledge is the experience of the senses. But the knowledge which we acquire from experience is partly composed of that which we acquire through the sense impressions and partly from that which our own intellectual powers supply from themselves; in other words, our knowledge of the world is conditioned not simply by the nature of the external world but also by that of our organs of knowledge. For a knowledge of the world therefore the investigation of our own intellectual powers is as necessary as that of the external world. The investigation of the first is, however, the duty of philosophy; while the second is the science of science.
In this there is nothing contained that every Materialist could not subscribe to, or that, perhaps with the exception of the last sentence, had not also been previously said by Materialists. But certainly only in the way in which certain sentences from the Materialist Conception of History had already been expressed before Marx, as conceptions which had not borne fruit. It was Kant who first made them the foundation of his entire theory. Through him did philosophy first become the science of science, whose duty it is not to teach a distinct philosophy but how to philosophise, the process of knowing, methodical thinking, and that by way of a critique of knowledge.
But Kant went farther than this, and his great philosophical achievement, the investigation of the faculties of knowledge, became itself his philosophical stumbling block.
