The philosophy of science embraces the metaphysical, epistemological and methodological problems which arise in the study of the special sciences and perhaps no branch of the philosophy of science is more deserving of careful investigation than the borderline discipline between philosophy and scientific psychology. The philosophical problems resulting from the impact of psychology upon philosophy include such traditional problems as the existence, nature and origin of consciousness, the relation of the conscious to the unconscious and subconscious mind, the nature and continuity of the self, and the relation of consciousness to its neural conditions. All these problems originate in empirical psychology and are soluble, if at all, only by appeal to psychological evidence and thus through the cooperative efforts of the philosopher and the psychologist. Unfortunately the gulf between philosophers and psychologists is as wide if not wider than that which exists between philosophers and other groups of scientists. The chief obstacle to a philosophical psychology is the alienation of psychology from philosophy which followed the attainment by psychology of its status as an independent science. Psychology as a young and vigorous science, revolting against the parental restraint of philosophy, utterly repudiated philosophy and philosophical modes of thought and, at the same time, philosophy on its side breathed a sigh of relief to be rid of a difficult and recalcitrant offspring. Thus psychological science became more hostile to philosophy than her elder sister sciences, and philosophy went its own speculative way in utter disregard of scientific psychology. Indeed “Psychologismus” has become among philosophers a term of such severe reproach that to refute a philosophical position in certain quarters one need only demonstrate that it is psychological in its origin and foundation. Thus the revolt of psychology against philosophy, natural and inevitable though it was, has been so violent and prolonged as to be detrimental to both psychology and philosophy alike.