In Philosophy for April 1961 Mr J. R. Lucas argues that Gödel's theorem proves that Mechanism is false. I wish to dispute this view, not because I maintain that Mechanism is true, but because I do not believe that this issue is to be settled by what looks rather like a kind of logical conjuring-trick. In my discussion I take for granted Lucas's account of Gödel's procedure, which I am not competent to criticise.