The author considers the importance of the relationship between philosophy and psychiatry in general. He believes that the special sciences are necessary for the philosopher in supplying him with sufficient reliable data for study. On the other hand, the success of the sciences has always depended to a considerable extent upon their philosophic foundations. Dr. Richfield critically evaluates various past contributions of psychiatrists and philosophers in regard to the role of philosophy in theoretical psychiatry. He concludes with the statement that philosophy cannot fulfil the functions of any special science, natural or social, but it is a necessary instrument because of the indispensable role of the formal components in all theorizing activity. 'But the formal and the material do not exist apart and, although it appears as merely an aphorism, the preservation of the integrity of any object under investigation requires the mutual dependence of philosophy and science.'