Plasticity, Numerical Identity,and Transitivity

Abstract

In a recent paper, Chunghyoung Lee argues that, because zygotes are developmentally plastic, they cannot be numerically identical to the singletons into which they develop, thereby undermining conceptionism. In this short paper, I respond to Lee. I argue, first, that, on the most popular theories of personal identity, zygotic plasticity does not undermine conceptionism, and, second, that, even overlooking this first issue, Lee’s plasticity argument is problematic. My goal in all of this is not to take a stand in the abortion debate, which I remain silent on here, but, rather, to push for the conclusion that transitivity fails when we are talking about numerical identity of non-abstract objects.