Personal identity, multiple personality disorder, and moral personhood

Marya Schechtman argues that psychological continuity accounts of personal identity, as represented by Derek Parfit's account, fail to escape the circularity objection. She claims that Parfit's deployment of quad-memory (and other quasi-psychological) states to escape circularity implicitly commit us to an implausible view of human psychology. Schechtman suggests that what is lacking here is a coherence condition, and that this is something essential in any account of personal identity. In response to this I argue first that circularity may be escaped using quasi-psychological states even with the addition of the coherence condition. Second, I argue that there is something right about the coherence condition, and a major task of this paper is to identify its proper theoretical role. I do so by reflection on integration therapies for people with multiple personality disorder (MPD). The familiar distinction between the moral and the metaphysical concept of the person is developed alongside such reflection. Connecting these two issues I argue that coherence acts as a normative constraint on accounts of personal identity, but that the normative dimension of personhood is not essential to our notion of a person tout court.