III. The Validity of Knowledge
After having gained the insight which I hope we have gained in the first two lectures it will be profitable and perhaps enjoyable to view some of the great issues of traditional philosophy from the standpoint to which our simple considerations have taken us. We shall be surprised to notice how elevated this point of view is considering the shortness of the climb, and the easiness of the steps by which we have reached it.
We have raised ourselves to such a height, or at least to such a favourable standpoint that for us the traditional problems have lost their formidable aspect entirely, and can be overcome without difficulty, although, perhaps, in an unexpected way.
The so-called philosophical problems are usually believed to be interconnected in such a way, that if you solve a single one completely, you have at the same time shown the way to the solution of all the rest. In other words: it is believed that what you need in philosophy is one fundamental idea which will serve as a key to all the important issues as well as all the minor questions. This belief caused the great thinkers of the past to build up their philosophies in the form of a system, which means a coherent whole in which all the single truths are based on and held together by, one fundamental principle. I cannot share this belief because I cannot adopt (for reasons which will become apparent very soon) the definition of philosophy on which it rests; nevertheless it remains true that as soon as you really see through one of the so-called philosophical problems with perfect clarity, you have done with all of them. Thus in order to see how these problems are disposed of from our point of view, it will be sufficient to concentrate our attention on one of the great questions, and I propose to select the problem of the Validity of Knowledge.
This issue forms the centre of Kant's philosophy, and it is here, where
