Personal identity in the light of brain physiology and cognitive psychology

The concept of the person, and the notion that the latter is an entity separate and distinct from other persons, has persisted as one of the more secure "givens" of philosophical thought. We have very little difficulty, in observer language, in pointing to a person, describing his or her attributes, distinguishing him or her from other persons, etc. Likewise, it is ordinarily not much of a problem to subjectively experience, both sensorially and conceptually, the self - that is, to distinguish in agent language "my person" from the rest of the universe. The second of these two perspectives on the person defines the "I," "ego," or "identity." Several recent developments in experimental psychology and brain science - while not defeating the ordinary notion of the person on the merits of data per se - at least force a re-thinking of tacit assumptions basic to our sense of the concepts of both the person and personal identity. In this paper, I would like to show how the concept of the person needs revision, and at the same time to raise some objections to Shaffer's (1977) account of the consequences of brain bisection and brain transplant with respect to the fate of the person and his identity.