Substance dualists will sometimes appeal to the persistence of identity through physical change to argue against physicalism. The physical parts of you, like the cells of your body, are replaced over and over again, and yet your essential identity remains. 1/

There must be something non-physical about you, they argue, since basic information about you persists, though your brain cells are constantly being replaced. But this is mistaken because the arrangement and configuration of the brain is not significantly changing. 2/

Fingerprints are a good analogy here. The specific pattern that defines your fingerprints doesn’t change, even though the skin cells are constantly being replaced. Does this mean that fingerprints are made of some immaterial substance as well? 3/

There’s no need to postulate an immaterial self to explain persistence through time any more than we need to postulate an immaterial fingerprint to explain that part of you remaining constant. 4/4