For two things both to believe that snow is white, they need not to be physically similar in any specifiable way, but they must both be in a "functional" condition or state specifiable in the most functional language; they must share a Turing machine description according to which they are both in some particular logical state (which is roughly like two different computers having the same program and being in the same "place" in the program). … it is a type functionalism—each mental type is identifiable as a functional type in the language of Turing machine description.

p. xvi - Brainstorms (1978)