Steven Pinker -- How the Mind Works - Hampshire High Italian ...

Thinking Machines 97The other attack on the computational theory of mind comes from themathematical physicist Roger Penrose, in a best-seller called TheEmperor's New Mind (how's that for an in-your-face impugnment!). Penrosedraws not on common sense but on abstruse issues in logic andphysics. He argues that Godel's famous theorem implies that mathematicians—and,by extension, all humans—are not computer programs.Roughly, Godel proved that any formal system (such as a computer programor a set of axioms and rules of inference in mathematics) that is evenmoderately powerful (powerful enough to state the truths of arithmetic)and consistent (it does not generate contradictory statements) can generatestatements that are true but that the system cannot prove to be true.Since we human mathematicians can just see that those statements aretrue, we are not formal systems like computers. Penrose believes that themathematician's ability comes from an aspect of consciousness that cannotbe explained as computation. In fact, it cannot be explained by theoperation of neurons; they're too big: It cannot be explained by Darwin'stheory of evolution. It cannot even be explained by physics as we currentlyunderstand it. Quantum-mechanical effects, to be explained in an as yetnonexistent theory of quantum gravity, operate in the microtubules thatmake up the miniature skeleton of neurons. Those effects are so strangethat they might be commensurate with the strangeness of consciousness.Penrose's mathematical argument has been dismissed as fallacious bylogicians, and his other claims have been reviewed unkindly by experts inthe relevant disciplines. One big problem is that the gifts Penrose attributesto his idealized mathematician are not possessed by real-life mathematicians,such as the certainty that the system of rules being relied onis consistent. Another is that quantum effects almost surely cancel out innervous tissue. A third is that microtubules are ubiquitous among cellsand appear to play no role in how the brain achieves intelligence. Afourth is that there is not even a hint as to how consciousness might arisefrom quantum mechanics.The arguments from Penrose and Searle have something in commonother than their target. Unlike the theory they attack, they are so unconnectedto discovery and explanation in scientific practice that they havebeen empirically sterile, contributing no insight and inspiring no discoverieson how the mind works. In fact, the most interesting implication of