On the Supposed Inconceivability of Absent Qualia Functional Duplicates—a Reply to Tye

In “Absent Qualia and the Mind-Body Problem,” Michael Tye (2006) presents an argument by which he claims to show the inconceivability of beings that are functionally equivalent to phenomenally conscious beings but lack any qualia. On that basis, he concludes that qualia can be fully defined in functional terms. The argument does not suffice to establish the claimed results. In particular it does not show that such absent qualia cases are inconceivable. Tye’s argument relies on a principle P according to which the exchange of isomorphic states between functionally equivalent systems will preserve their equivalence. If they were functionally equivalent before the exchange, they will also be so after. Consideration of the contextual nature of realization shows that Principle P is not a general truth as Tye claims, and his argument against the possibility of absent qualia thus fails.