Full Idea
Functionalism has been rejuvenated by being joined to externalist causal theories of reference.
Gist of Idea
Functionalists like the externalist causal theory of reference
Source
John Searle (The Rediscovery of the Mind [1992], Ch. 2.VIII)
Book Reference
Searle,John R.: 'The Rediscovery of the Mind' [MIT 1999], p.49
A Reaction
This, however, seems to be roughly the reason why Putnam gave up his functionalist theory. See Ideas 2332 and 2071. However the causal network of mind can incorporate environmental features.
Related Ideas
Idea 2332 Functionalism can't explain reference and truth, which are needed for logic [Putnam]
Idea 2071 If concepts have external meaning, computational states won't explain psychology [Putnam]