If Turing’s thesis [i.e., the Church-Turing thesis] is correct, stored-program computers can perform any computation (until they run out of memory) and can reproduce mental processes (p. 27).The italicized part is a perfect example of what Jack Copeland calls the Church-Turing fallacy, namely, the mistake of supposing that the computational theory of mind, or the view that mental processes are computational (and more specifically, that they are computable by Turing machines) follows from the Church-Turing thesis. Sadly, the Church-Turing fallacy is common among philosophers. Even more sadly, it is now firmly inserted in the entry on AI in the Routledge Encyclopedia of Philosophy of Science. Worse for me is, my name is at the bottom of that entry!
The most upsetting part of the story for me is that the offending statement was not in the original article that I submitted to the editors. The original text, which I wrote, read:
If Turing’s thesis is correct, stored-program computers can perform any computation (until they run out of memory). If McCulloch and Pitts’s theory [to the effect that mental processes are computational] is also correct, stored-program computers can reproduce mental processes.Obviously, this is very different. Somehow, after I submitted the entry, the antecedent of my second conditional got deleted and the rest of the sentence merged with the previous sentence, turning two relatively uncontroversial statements into a fallacious one. Unfortunately, there was no proof correction, and thus no opportunity for me to notice this mistake, before publication.
I actually have a forthcoming article in Synthese criticizing arguments for the computational theory of mind that appeal to the Church-Turing thesis. Of all people, I am the last (with the possible exception of Jack Copeland) who should get caught committing the Church-Turing fallacy. Alas.