 No one who thinks that we persist by virtue of memory continuity would accept this. The memory criterion is intended to imply that if a person x exists now and a being y exists at another time--whether or not it is is a person then--they are one just if x can now remember an experience y has at the other time or vice versa. But this not an answer to Question 1: what it takes for a person existing at one time and a person existing at another time to be one rather than two. It is an answer to a more general question: what it takes for something that is a person at one time to exist at another time as well, whether as a person or not: