The Philosophical Zombie
While no philosophers assert that zombies exist, the philosophical zombie has been employed as a thought exercise to refute the claims of materialists.
In the nineteenth century, following a cascade of scientific breakthroughs, materialism began to gain favour as an epistemological argument. Thinkers like G.F. Stout and David Chalmers have since challenged the notion of evolution and Darwinism as evidence of materialism's strength.
Imagine a zombie world, exactly like this one, with the same physical laws, conditions, and species. Each of us has a zombie twin, with identical physical characteristics, that interacts with the world in the exact same way we do. Except our zombie twin lacks non-physical consciousness. In the zombie world, there are no conscious experiences.
Would the zombies act the same way as we do? Would they feel pain? Would they see colour? If they wouldn't, then materialism as a position in the mind-body debate is untenable.