 We sometimes ask what it takes for someone to remain the same person. The idea is that if you were to alter in certain ways—if you lost much of your memory, say, or became badly disabled, or had a dramatic change in character—you would no longer be the person you were before. This is not the persistence question. The two questions can have different answers. Suppose you change in such a way as to “become a different person”: the answer to the question of whether you are the same person is No. The persistence question asks, in this case, whether you would still exist. And the answer to that question is Yes: if you are a different person, then you still exist, just as you do if you remain the same person. 