Abstract

In both biology and psychology, the notion of an individual is indispensable yet puzzling. It has played a variety of roles in diverse contexts, ranging from philosophical problems of personal identity to scientific questions about the immunological mechanisms for telling ‘self’ from ‘non-self.’ There are notorious cases in which the question of individuality is difficult to settle — ant hill, slime mold, or beehive, for instance. Yet the notion of an individual organism, both dependent on and independent of other individuals in specific ways, is crucial to our conception of life itself. It is also crucial to our notion of mentality, and hence to other concepts — moral and social — which must be explicated in terms of individual mentality. (Think, for example, of the importance of the quality and nature of individual consciousness to debates about abortion and euthanasia.)