This chapter shows that there are two main lines of objection to the theory that personal identity can be defined in terms of psychological continuity. The first was the reduplication argument. The second is the vicious-circularity objection: the objection that any account of personal identity in terms of memory will necessarily be viciously circular, since memory presupposes personal identity and, therefore, cannot be used to define it. The chapter looks at the vicious-circularity objection. The memory criterion, or the psychological-continuity criterion, of personal identity can then be rendered safe from the vicious-circularity objection by the simple device of replacing all references to ‘memory’ by references to ‘quasi-memory’. Quasi-memory the understood seems a clearly intelligible idea. To quasi-remember performing an action is, by definition, to have an apparent memory of performing that action.