Counterfactuals cannot count: a rejoinder to David Chalmers.

The initial argument presented herein is not significantly original--it is a simple reflection upon a notion of computation originally developed by Putnam (Putnam 1988; see also Searle, 1990) and criticised by Chalmers et al. (Chalmers, 1994; 1996a, b; see also the special issue, What is Computation?, in Minds and Machines, 4:4, November 1994). In what follows, instead of seeking to justify Putnam's conclusion that every open system implements every Finite State Automaton (FSA) and hence that psychological states of the brain cannot be functional states of a computer, I will establish the weaker result that, over a finite time window every open system implements the trace of FSA Q, as it executes program (P) on input (I). If correct the resulting bold philosophical claim is that phenomenal states--such as feelings and visual experiences--can never be understood or explained functionally. Copyright 2002 Elsevier Science (USA)