Philosophical questions about the mind preoccupied much of Wittgenstein's later writing, and his contribution to them is deep and wide-ranging, bearing upon philosophical issues concerning sense-experience, concept formation, perception, introspection, the science of psychology, aspect perception, the self, the understanding of rules, the relation between mind and brain, artificial intelligence, and many other subjects of current concern. According to a growing number of eminent philosophers, however, many of Wittgenstein's most important insights still have not been properly absorbed by...