They have also assumed that the interrogation of experience is a straightforward operation. But they have recognized that the main effort is to be devoted to the discovery of propositions which do in fact conform to experience. Thus the moderns stress induction. The view which I am maintaining is that none of these operations are easy. In fact they are extremely difficult. Apart from a complete metaphysical understanding of the universe, it is very difficult to understand any proposition clearly and distinctly, so far as concerns the analysis of its component elements.
Again the analysis of experience without the introduction of interpretive elements which may be faulty, is extremely difficult. It follows also from these two difficulties that judgment of direct conformity to experience is very difficult to bring to a decisive issue, with the elimination of all elements of doubt.
There is also some doubt even as to the self-consistency of a proposition. For if the analysis of the proposition be vague, there is always a possibility that a more complete analysis will disclose a flaw. The same doubt also applies to the fourth criterion which is that of external consistency. In this case we are comparing the proposition under the scrutiny with other propositions accepted as true.
It is obvious that if the first two criteria were capable of easy determination nothing else would be wanted. Also if the first four criteria could be decisively determined, the fifth criterion would be
