Abed's (Reference Abed2000) enthusiastic advocacy of evolutionary psychology contains much that is sensible but its central hypothesis that psychiatry is weak because of its conceptual pluralism is unsatisfactory. Conceptual pluralism may be a sign of weakness but it is hardly unique to psychiatry. Abed's example of a physicist not violating the Newtonian law of gravity is particularly unfortunate. Einstein's general theory falsified the Newtonian theory of gravity nearly 100 years ago, but physicists still use the Newtonian theory when it is useful. Indeed modern physics abounds with mutually incompatible theories, and the mutually incompatible corpuscular and wave theories of light have been jostling side by side for a couple of centuries. If physics, the fundamental science, tolerates conceptual pluralism, then the other sciences, which are based on the laws of physics, cannot be criticised too severely for also being pluralistic.

This has led some philosophers of science to suggest that it is unrealistic for science to aim at the truth; rather, the purpose of scientific hypotheses is to provide a theoretical framework to help us overcome problems that we encounter in nature — the instrumentalist view (Reference van Fraassenvan Fraassen 1980; Reference Churchland and HookerChurchland & Hooker, 1985). This instrumentalist view of science is less ambitious, but given the history of science seems more practical and persuasive. We should not, therefore, be too embarrassed by the conceptual pluralism of psychiatry — we are in good company.