The notion of identity raises a number of philosophical problems, including the identity of indiscernibles. The latter postulates that there cannot be separate objects or entities that t have all their properties in common.

The mind-body problem is the problem of determining the relationship between the human body and the human mind. Philosophical positions on this question are generally predicated on either a reduction of one to the other or a belief in the discrete coexistence of both.

Theseus’s paradox is a thought experiment that raises the question of whether a ship—standing for an object in general—that has had all of its components replaced remains fundamentally the same object.