He is Alan Alda playing a philosophy professor. He looks like Peter gone solo without Paul and Mary, with a graying goatee, carefully trimmed sideburns, and balding pate. His required text, Inference and Imagination by J. M. Dolan, is littered with amusing quotes, cartoons, and anecdotes. Before Inference and Imagination by J. M. Dolan came out in print two years ago, Professor Dolan provided his students with a photocopied version. He offers extra credit to students who spot errors in the book. His lectures sometimes stray from this text, but they soon return with the predictability of a well-constructed logic problem.