What is thought? By Eric Baum. Cambridge, MA: MIT Press, 2004. Pp. 495. ISBN 0262025485. $45 (Hb).

Reviewed by Chaoqun Xie, Fujian Normal University

What is the mind? How does the mind work? The ‘mind’ question is one of complexity and difficulty, and scholars make continued efforts to find answers to it. Although there are different approaches to this question from different perspectives, there appears to be one thing in common, that is, the mind is often talked about metaphorically (see e.g. The literary mind, by Mark Turner (Oxford University Press, 1996) and The algebraic mind by Gary F. Marcus (MIT Press, 2001)). What is thought? also talks about the mind metaphorically, but in this case, the mind is thought of as a computer program. In this work, Eric Baum, a computer scientist, aims to draw ‘the most straightforward, simplest picture of mind’ (2).

What is thought?, which is patterned after Erwin Schrödinger’s What is life? (Cambridge University Press, 1944), contains fifteen chapters. In Ch. 1, the introduction, B points out that the whole book can be summed up in a single sentence, namely, ‘Semantics is equivalent to capturing and exploiting the compact structure of the world, and thought is all about semantics’ (3). Or, to put it more succinctly, the mind is nothing but a program. The remaining fourteen chapters are devoted to the justification of this underlying theme, which, as B confidently claims, ‘explains everything, and does so economically’ (31). The chapters are as follows: ‘The mind is a computer program’, ‘The Turing test, the Chinese room, and what computers can’t do’, ‘Occam’s razor and understanding’, ‘Optimization’, ‘Remarks on Occam’s razor’, ‘Reinforcement learning’, ‘Exploiting structure’, ‘Modules and metaphors’, ‘Evolutionary programming’, ‘Intractability’, ‘The evolution of learning’, ‘Language and the evolution of thought’, and ‘The evolution of consciousness’.

To justify the central premise of the book, B draws upon, among other things, recent developments in artificial intelligence and neural networks, thinking highly of and attaching great importance to the modularity of mind and Occam’s razor. He argues, among other things, that ‘life is the execution of the DNA program’ (7), that ‘the mind is an evolved program that exploits the compact underlying structure of the world’ (14), and that Occam’s razor ‘is the basis of mind itself’ (8). For B, ‘our minds do vast computations of which we are not consciously aware’ (408).

All in all, this is an exciting book simply because it provides an exciting answer to an exciting question. The picture of mind as drawn by B is largely informative, impressive, and persuasive, and would surely contribute to human understanding of how the mind works. Students of artificial intelligence, linguistics, philosophy of language, philosophy of mind, and psychology would find this title intriguing, thrilling, and encouraging. In fact, anyone intending to know more about the nature of thought should not miss this book.

I have some additional comments. First, it seems to me that the ‘most straightforward, simplest picture of mind’ does not necessarily entail that it is the most true-to-life picture; an easy and exciting answer is not necessarily equal to a correct answer. Second, B subscribes to the prescription of Occam’s razor that ‘given any set of facts, the simplest explanation is the best’ (8). In fact, the simplest is not necessarily the best because, for it to be the best, it should first and foremost be correct. Who decides the correctness of the simplest? Which is correct, and which is not? The modularity hypothesis is not without problems either. Third, any book on the human mind is destined to be at once thought-provoking and controversial. This book is no exception, and that may in part explain why B is ‘confident that the picture herein will not convince all readers’ (2).