Theories of functionalism in the philosophy of mind rely on the core idea that physical systems realize certain functional profiles. Kevin Lande (Brandeis) presents a case in which the realization relation is underdetermined: even considering all the relevant physical facts and causal laws, the same physical system can be said to realize different functional organizations.
Lande argues that underdetermination is highly problematic for functionalism. In order to allow for cases of underdetermination, the functionalist will either be committed to a contradiction, or will have to violate supervenience.
From “Consciousness and the Brain,” the Interdisciplinary Graduate Conference on Consciousness, Boston, April 2011. Video production sponsored by the Mind Science Foundation.