Some philosophers have used such dualist intuitions to challenge mind-brain identity through thought experiments. The most prevalent is the “zombie” argument, which goes like this. Imagine people who are just like us in all physical respects but differ only in that they lack consciousness.
Call them zombies, although they are not like the fearsome zombies of horror movies. Such people are clearly conceivable—just think of anyone you know and imagine that he or she is not really conscious but only seems to be. Because we can imagine beings that are physically identical to us but lack conscious experience, conscious minds are not necessarily identical to brains. But for an identity
statement to be true, it has to be necessarily true, true in all possible worlds, like any identity statement, such as A = A. Hence the possibility of zombies shows that it is not necessarily true that minds are brains, so it is not true at all. There must be more to consciousness than brain states.