This is the problem of "personal identity" in metaphysics. First of all, I'm sorry to say to the landlord that the debate among philosophers on this issue has not been finalized.

Next, I will briefly introduce it with my own humble opinion.

There are generally two theories about the definition of "self": 1 and personality theory. 2, the body said. "Personality theory" means that human nature is "personality". Descartes is the earliest and most typical representative of this theory, and his famous saying "I think, therefore I am" means this. "Body theory" means that human nature is "body" and opposes taking "soul" or "mind" as an independent entity. Of course, modern physicalism tends to the latter, that is, people are "living beings"; It is also believed that there is no "soul", and "mind" is only the expression of the brain (the identity and non-identity of "mind" and "brain" are topics in the philosophy of mind, so I will not repeat them here).

Criticism of the above two viewpoints: the dilemma of "personality theory" lies in "what is the key to personality?" Is it the soul (Descartes)? Memory (Locke)? Not at all (Hume)? Of course, there is what physicists call "brain data" (but this can't solve the problem, because there is still a difficult problem, that is, "the relationship between heart and brain"). The dilemma of the "body theory" is that "obviously I have thinking, and it is because of thinking that I become a person."

There is also a theory that there is no real personality at all (for example, in Indian philosophy, people have multiple selves). Hermann hesse also said in Wolf of the Wilderness: "Man is an onion made of a thousand layers of skin, a fabric made of countless threads."

Ok, that's the end of the introduction. It is not easy for the subject to think of the example of "copying the soul", which is somewhat similar to the "torture theory" in academic circles.

More information can be found in the open video "Philosophy of Death" of Yale University. If I remember correctly, it was in the episode 1 1 to 14. In youku.

There is a saying in Zhihu that if a person is ground into atoms and reassembled, will he still be the same person? The problem is to discuss this. Link: /question/26630283)