In the First Lecture, which I had the pleasure of delivering here a few months ago, I tried to give a short sketch of the nature and method of philosophy; and I spoke about the position which I think philosophy will take in the future after its real nature has been more generally and more properly understood.
Today I shall try to outline the results of a consistent application of the true method of philosophy to one or two of the great traditional problems. There are different ways of approaching philosophy, but the most natural one is to start from some fundamental issue around which all the other problems seem to group themselves in a systematic order.
Such a central problem with which I should like to begin is the question, “What can we know?” It is a truly fundamental issue. Kant spoke of this question as one of the three great questions which metaphysics has to answer. No other problem causes such a sharp division between the various schools of philosophy and the answer given to this question characterizes the philosophical systems and mental attitudes better than anything else. We find within ourselves a thirst for knowledge, a desire to explain, a craving for answers to endless questions; and every one who thinks has some moments in his life when he asks himself. “Can this thirst be quenched at all? Can this desire for knowledge be satisfied; and if so, how far can it be satisfied?” In other words, the problem seems to be, “What questions can be answered?”
There are two extreme positions which can be taken in regard to this question. One would be to answer, “We cannot know anything; no questions can be finally answered.” And the other one would be to say, “We can know everything, and there is no question which cannot finally be answered by the human mind.” The first of these attitudes is called skepticism, and the second one would be called, perhaps, dogmatism. The skeptic doubts everything, and the dogmatist does not suffer his fundamental beliefs to be touched by any doubt.136
