Functionalists in philosophy of mind traditionally raise two major arguments against the type identity theory: (1) psychological states are multiply realizable so that there are no one-to-one mappings of psychological states onto neural states and (2) the most that evidence could ever establish is the correlation of psychological and neural states, not their identity. We defend a variant on the traditional type identity theory which we call heuristic identity theory (HIT) against both of these objections. Drawing its inspiration from scientific practice, heuristic identity theory construes identity claims as hypotheses that guide subsequent inquiry, not as conclusions of the research.