A refutation of Penrose's Gödelian case against artificial intelligence

Having, as it is generally agreed, failed to destroy the computational conception of mind with the Gödelian attack he articulated in his The Emperor’s New Mind, Penrose has returned, armed with a more elaborate and more fastidious Gödelian case, expressed in Chapters 2 and 3 of his Shadows of the Mind. The core argument in these chapters is enthymematic, and when formalized, a remarkable number of technical glitches come to light. Over and above these defects, the argument, at best, is an instance of either the fallacy of denying the antecedent, the fallacy of petitio principii, or the fallacy of equivocation. More recently, writing in response to his critics in the electronic journal Psyche, Penrose has offered a Gödelian case designed to improve on the version presented in SOTM. But this version is yet again another failure. In falling prey to the errors we uncover, Penrose’s new Gödelian case is unmasked as the same confused refrain J.R. Lucas initiated 35 years ago. ∗We are indebted to Martin Davis, Kelsey Rinella, Marvin Minsky, David Chalmers, Jim Fahey, Michael Zenzen, Ken Ford, Pat Hayes, Bob McNaughton, and Kostas Arkoudas. Selmer would like to express special thanks to Roger Penrose for debate and conversation concerning many of the issues treated herein. Bringsjord and Penrose both believe that the mind is beyond computation; both also believe that Gödelian results can be deployed to demonstrate this. However, as this paper testifies, they differ over how to carry out the demonstration.