Full Idea
I speak of my view as the Causal version of functionalism, which asserts that mental states are states apt for the production of certain ranges of behaviour and, in some cases, apt for being produced by certain ranges of stimuli.
Gist of Idea
Causal Functionalism says mental states are apt for producing behaviour
Source
David M. Armstrong (Pref to new 'Materialist Theory' [1992], p.xiv)
Book Reference
Armstrong,D.M.: 'A Materialist Theory of Mind' [Routledge 1993], p.-10
A Reaction
This effectively makes a mental state a place in a flowdiagram (and hence the mind is software). It says nothing about what qualities the mental states have which make them apt for this role. Full explanations need more than the function.