What distinguishes clever computers from stupid people (besides their components)? The author of Seeing and Knowing presents in his new book a beautifully and persuasively written interdisciplinary approach to traditional problems—a clearsighted interpretation of information theory. Psychologists, biologists, computer scientists, and those seeking a general unified picture of perceptual-cognitive activity will find this provocative reading. The problems Dretske addresses in Knowledge and the Flow of Information —What is knowledge? How are the sensory and cognitive processes related? What makes mental activities mental?—appeal to a wide audience. The conceptual tools used to deal with these questions (information, noise, analog versus digital coding, etc.) are designed to make contact with, and exploit the findings of, empirical work in the cognitive sciences. A concept of information is developed, one deriving from (but not identical with) the Shannon idea familiar to communication theorists, in terms of which the analyses of knowledge, perception, learning, and meaning are expressed. The book is materialistic in spirit—that is, spiritedly materialistic—devoted to the view that mental states and processes are merely special ways physical systems have of processing, coding, and using information.