A fictional dialogue between five seminal modern thinkers, on the thorny subject of artificial intelligence. Casti (Would-Be Worlds, 1996) postulates that in June of 1949, the British government asks physicist and novelist C.P. Snow to sound out the scientific community on the subject of “thinking machines.” In response, Snow throws a special dinner at Cambridge for mathematician Alan Turing, geneticist J.B.S. Haldane, physicist Erwin Schrîdinger, and philosopher Ludwig Wittgenstein. This book is an account of their imaginary meeting, as well as a portrait of these five remarkable personalities. By 1949, Turing’s mathematics had laid the groundwork for the idea of a programmable computer, which he explains to the other guests to begin the discussion. At first, the gruff Haldane acts as the voice of “common sense,” asking what a simple “Turing Machine” is actually good for. Schrîdinger is quicker to see the mathematical implications, but Wittgenstein questions whether a finite machine can mimic any natural phenomenon at all, let alone one as complex as thought. Over the course of the evening, Turing continues to explain his ideas (including the “Turing test”) using various dishes and implements as the dinner progresses, while the urbane Snow acts as host and master of ceremonies. The others offer insights or criticisms of Turing’s model, bringing in such familiar concepts as the “Chinese room” (here recast in terms of hieroglyphics) in which a translator merely manipulates symbols without understanding them; can he be said to think? The holes in the various arguments are exposed, and many of the central ideas of today’s artificial-intelligence debates are clearly outlined in these discussions. While Casti’s attempts to blend exposition and dialogue are wooden, he does a good job of laying out the key philosophical issues raised by artificial intelligence, and of delineating the thought of these five men. Historians of science will enjoy this imaginary meeting of minds; others may find the fare too esoteric.