A slew of conceivability arguments have been given against physicalism. Many physicalists try to undermine these arguments by offering accounts of phenomenal concepts that explain how there can be an epistemic gap, but not an ontological gap, between the phenomenal and the physical. Some complain, however, that such accounts fail to do justice to the nature of our introspective grasp of phenomenal properties. A particularly influential version of this complaint comes from David Chalmers (1996; 2003), who claims, in opposition to (...) the accounts of phenomenal concepts described above, that phenomenal concepts have primary and secondary intensions that coincide in all worlds. In this paper, I construct an argument that casts doubt upon Chalmers' claim. At the heart of this argument is an idea that Chalmers shows some affinity for: namely, that introspection doesn't reveal whether phenomenal properties are fundamental properties or whether they are derived from more basic protophenomenal properties. I argue that this claim implies that the primary and secondary intensions of our phenomenal concepts do not coincide in all worlds. In this way, I show that a plausible idea about the powers of introspection – an idea that Chalmers himself is drawn to – is a reason for rejecting the claim that phenomenal concepts have primary and secondary intensions that coincide in all worlds. (shrink)