But if the universal character of the hypothesis and the tested theory belong to the instrumental character of thought in so reconstructing a world that has proved to be imperfect, and inadequate to conduct, the stuff of the world and of the new hypothesis are the same. At least this is true for the scientist who has no interest in an epistemological problem that does not affect his scientific undertakings in one way nor another. I have already pointed out that from the standpoint of logical and psychological analysis the things with which science deals can be neither ultimate elements nor sense-data; but that they must be phases and characters and parts of things in some whole, parts which can only be isolated because of the conflict between an accepted meaning and some experience. I have pointed out that an analysis is guided by the practical demands of a solution of this conflict; that even that which is individual in its most unique sense in the conflict and in attempts at its solution does not enter into the field of psychology--which has its own problems peculiar to its science. Certain psychological problems belong to the problems of other sciences, as, for example, that of the personal equation belongs to astronomy or that of color vision to the theory of light. But they bulk small in these sciences. It cannot be successfully maintained that a scientific observation of the most unique sort, one which is accepted for the time being simply as a happening in this or that scientist's experience, is as such a psychological datum, for the data in psychological text-books have reference to _psychological_ problems. Psychology deals with the consciousness of the individual in its dependence upon the physiological organism and upon those contents which detach themselves from the objects outside the individual and which are identified with his inner experience. It deals with the laws and processes and structures of this consciousness in all its experiences, not with _exceptional_ experiences. It is necessary to emphasize again that for science these particular experiences arise within a world which is in its logical structure organized and universal. They arise only through the conflict of the individual's experience with such an accepted structure. For science individual experience _presupposes_ the organized structure; hence it cannot provide the material out of which the structure is built up. This is the error of both the positivist and of the psychological philosopher, if scientific procedure gives us in any sense a picture of the situation.