Out of the Ordinary: An Evaluation of Geach's Argument for Immaterialism

Peter Geach offers a novel argument for the immaterialist conclusion that thinking is not a physical activity performed. Two crucial premises of Geach's argument are that thinking is a basic activity and that thinking is a non‐clockable activity. It is argued that since Geach does not clarify in exactly what sense thinking is supposed to be a basic activity, the first premise of his argument has not been justified. It is then argued that the same Wittgensteinian considerations Geach takes to show that there are no interior acts of meaning also show that there are no interior acts of thinking and hence no non‐clockable interior acts of thinking. Thus the second premise of Geach's argument also has not been justified. Therefore, Geach's argument is unconvincing as it stands.