Two thoughts: (1) are you thinking of these definitions as defining particulars? if they are general, then a definition can pick out an input-intermediate-output pattern without requiring "looking into the future".  

(2) I think there is a conflict between certain versions of functionalism, and mental causation; see my
Mental Causation (Columbia U Press, 2008), Chapter 7, and Robert Rupert, "Functionalism, Mental Causation, and the Problem of Metaphysically Necessary Effects" (Nous 2006).