In this paper I propose to examine some of the issues that arise when psychopathologists apply concepts such as "rationality", "reality testing", "contact with reality" and the like to the description of allegedly pathological states in psychiatric patients. A conference that brings philosophers and psychopathologists together appears to be a particularly appropriate locus for such discussion, the more so as psychopathologists generally tend to ignore philosophical aspects of their discipline, preferring instead to take for granted the assumptions that underlie their work. That they do so is a testimony not to a kind of cavalier indifference to philosophical matters in principle, but rather to a conviction that accumulated practical experience in the clinic provides a sufficiently reliable basis for professional action. This naturally brings with it the conviction that speculative examination of premises does not hold real promise of improving the practical clinical techniques that they employ.