The psychiatrist is confronted with many central issues of philosophy, but finds a philosophical training of no value. Hence he has become pragmatic, asking of a method only that it shall work and of a theory that it shall be self-consistent.
Some psychiatrists have been interested in philosophers, regarding their symptoms as symptoms of mental illness, because the medical aim is to eliminate subjective bias. This leads to the detraction of philosophy, which is improper in a psychiatrist. Thus the subjective colouring of Kant's interesting remarks about mental disease leads the psychiatrist to overlook their possible value.
Descartes took everything he could clearly and distinctly conceive to be true. Such clarity of conception is found, however, in many who are manifestly insane. This was pointed out by Locke, who mentions the same defect in connection with enthusiasts. Stace is cited, deploring the lack of psychological description of the process by which unreasoned beliefs, which play a large part in the thought of philosophers and ordinary people, are reached. There is evidence to justify the belief that the same causes of disortion operate in both healthy people and the mentally ill. But 'psychiatrists have been far more ready to admit that excessively misplaced doubt occurs in healthy people regarding true propositions than to recognize that misplaced certainty occurs in the healthy regarding false intuition' (p. 10).
If a few philosophers had had the syndrome of depersonalization and produced their philosophical works while suffering from it, what might they not have created? Psychiatrists might consider this syndrome a reductio ad absurdum of solipsism, but there is no philosophical study of it.
Psychiatrists are monists. But, because it is difficult to throw light on individuality by means of physiology, they use the language of dualism, and they shirk the problem of resolving this inconsistency. The paper ends with the present psychiatric description of consciousness and the difficulty of relating concepts about the unconscious to what is observable.