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Home , Neurophilosophy, Patricia Churchland, Saul Kripke

BOOKS et al. manufacture of proteins, but are not alive. Just as our ability to conceive of these func- tions without life does not show that life is or Philoneuroscience explanatorily independent of the physical, she argues, so the conceivability of zombies does not show that is explana- torily independent of the physical. Although hen, in 1986, cussion reveals no of the tremen- I am on Churchland’s side against dualism, I coined the term “neurophilosophy” dous ferment in over the last 15 don’t approve of her cavalier treatment of the W(1), few that years or recognition that this ferment often dualist’s position. Some of the philosophers neuroscience and had much to has of the science of the in whom she is arguing against hold (roughly) say to each other. Now, philosophical issues the background—examples include work by that life can be analyzed a priori in terms of involving neuroscience and (2, 3). a of functions such as reproduction, di- -Wise are mainstream philoso- Further, mainstream philosophers have pro- gestion, metabolism, etc. (this is explicit in Studies in phy. Brain-Wise is an in- vided about the very issues Chalmers’s book), but that consciousness Neurophilosophy troductory textbook in Churchland addresses, often from positions cannot be so analyzed. So they would regard by Patricia philosophy aiming to close to her own. For example, in a series of her deadbies as inconceivable and in that Smith Churchland show that discoveries in recent works (4), has produced way not analogous to zombies. cognitive science and exciting new arguments for the reductionist MIT Press, Cambridge, The “big questions” Churchland is after MA, 2002. 486 pp., neuroscience allow for point of view, based on considerations about include the of the self, the relation be- $65, £43.50. ISBN 0- “progress where progress causation and multiple realization, and these tween and , conscious- 262-03301-1. Paper, was deemed impossible” arguments have sparked an illuminating con- ness, and the justification of knowledge. $25, £16.95. ISBN 0- on the “big problems” of troversy. Although Churchland discusses According to Churchland, the self is a con- 262-53200-X. philosophy. The exposi- both causation and reduction at length, nected set of representational capacities that is tion of cognitive science what she says about these topics a locus of control. Free will and determinism and neuroscience is done with flair, , would have been broadened and are compatible because there is a real distinc- and clarity. Churchland (the chair of the deepened by more engagement with tion between control and out of control, even Philosophy Department, University of recent works. though actions in both categories are caused California, San Diego) has a great eye for and determined. The main line of her views philosophically interesting bits of the science on these big questions are familiar from of the mind. However, the ratio of philosophy thinkers who predate the neuroscientific to science is too low for a philosophy course claims she discusses. She elucidates em- and high enough to preclude it from adoption pirical claims made by some of the great in all but the most exceptional science cours- philosophers in the days before philoso- es, which leads one to wonder whether this Image not phy and psychology were distinct book has a market. available for fields—for example, the positions of In a that attracts extrem- online use. and Hume on the conditions ists—both reductionist and antireduction- required for a child to develop practical ist—Churchland has a sensible, balanced rationality. But this is not a case of view of the relation between cognitive sci- “progress where progress was deemed ence and neuroscience. Her view, which she impossible.” No one would have doubt- calls coevolution, is that the science of the ed that such empirical claims are subject mind requires investigation at many levels to empirical evaluation. and that these levels can mutually enrich one Churchland thinks the contact another. In the course of elaborating this Another way in which the points between philosophy and neuro- view, she provides an excellent discussion of book suffers from the neglect of science lie in what neuroscience has to say the rationale for theoretical identities (such appears in its su- about the big problems and in theoretical as heat = molecular kinetic energy). Here, as perficial treatment of views Churchland crit- neuroscience. But the first does not amount throughout the book, examples from the his- icizes, for example recent arguments for du- to much, and the second assumes that tory of science are brought in to good effect. alism offered by , David philosophical training somehow provides Although some of Churchland’s views Chalmers, and Frank Jackson (5–7). I can’t an advantage in constructing theories in have taken root in mainstream philosophy, explain their views or her criticisms in so neuroscience, something I doubt. she is not part of it. This distance shows in the short a space, but I will give one tiny exam- In my view, the intersections between phi- book, which suffers from a neglect of con- ple: her argument against their use of the losophy and the sciences of the mind reside temporary philosophy. For example, in her conceivability of “zombies” to argue for du- largely in smaller problems, conceptual is- chapter on epistemology (theory of knowl- alism. The dualists argue that the that we sues arising in the sciences themselves and edge), she wonders why traditional “non- can conceive of creatures physically exactly invoking or distinctions that have come empirical” epistemology still exists. Her dis- like us but with no consciousness shows con- up in philosophy or that are well served by sciousness is not physical. Churchland says the methods of philosophy. Philosophy is of- that we can also conceive of creatures ten defined as the study of issues in which the The reviewer is in the Department of Philosophy,503A Silver Center, 100 Washington (“deadbies”) that are physically like us and questions themselves are up for grabs. Thus it Square East, New York, NY 10003, USA. E-mail: possess mechanisms of reproduction, diges- is no surprise that the smaller problems are

[email protected] tion, respiration, growth, metabolism, and often messy and so are disdained by some— CREDIT:T. SMITH CHURCHLAND MARIAN PATRICIA CHURCHLAND/COURTESY

1328 5 SEPTEMBER 2003 VOL 301 SCIENCE www.sciencemag.org B OOKS ET AL. but definitely not all—scientists. Oddly, plexity of the gene-environment interaction. Churchland appears to adopt the “just the Lastly, in her discussion of consciousness, ” mindset of those scientists who are im- Churchland takes theories that see experiential patient with the more conceptual and founda- consciousness as a kind of brain activation and tional issues in their fields. theories that see the of consciousness Here is an example of the kind of issue I in terms of higher order cognitive states as am talking about. There has been a vigorous rivals. But many philosophers have suggested debate among both psychologists and that such theories may be talking about con- philosophers about whether mental images sciousness in different senses of the term: represent in the manner of pictures is one thing and experience accom- (Kosslyn) or in the manner of sentences panied by higher order is another. (Pylyshyn), and the discussion of this issue One would think a philosophical treatment of has involved conceptual issues about repre- the relation between these theories would at sentation that link up to long-standing - least discuss this possibility, if only to dismiss it. sophical literature. Although Churchland de- Brain-Wise makes many excellent votes an entire chapter to how the brain rep- methodological points and has some inter- resents, this issue does not come up. esting and sensible things to say about the Churchland’s impatience with foundational big problems of philosophy. Unfortunately, issues also extends to conceptual issues more Churchland, despite her militantly interdis- closely connected to the big problems. For ciplinary views, approaches many concep- example, anti-innatists have argued that no tual issues in the sciences of the mind like phenotypic characteristic can be genetically the more antiphilosophical of scientists. determined, because there is always some en- vironmental feature (even within the womb) in References and Notes which the phenotypic characteristic would not 1. P. Churchland, Neurophilosophy: Towards a Unified of the Mind-Brain (MIT Press, develop (e.g., as demonstrated in imprinting in Cambridge, MA, 1986). chicks). The innatists say that although every 2. T. Burge, Philos. Rev. 102, 457 (1993). phenotypic characteristic is produced by a 3. C. Peacocke, A Study of (MIT Press, Cambridge, MA, 1992). complex gene-environment interaction, in 4. These include J. Kim, Mind in a Physical World: An some cases when we ask where a certain phe- Essay on the Mind-Body Problem and Mental notypic informational structure comes from, Causation (MIT Press, Cambridge, MA, 1998). 5. S. Kripke, in of Natural ,D. the best answer is “from the genes.” This is the Davidson, G. Harman, Eds. (Reidel, Dordrecht, classic “poverty of the stimulus” argument. Netherlands, 1972), pp. 253–355. Churchland has a section on innateness, but in- 6D.Chalmers, (Oxford Univ. Press, New York, 1996). stead of grappling with this conceptual issue, 7. F. Jackson, From to Ethics: A Defence of she confines herself to describing the com- Conceptual Analysis (Clarendon, Oxford, 1998).

MATHEMATICS A Polemic on Probability Andrew H. Jaffe

hat is probability? This question probability is hopelessly, fatally subjec- has long puzzled scientists (who tive—“unscientific.” Wmust make inferences based on An important theme reiterated through- inexact data) as well as philoso- out the book is the phers like and poly- Probability Theory between frequencies, which may maths like John Maynard The of be objective experimental re- Keynes. In Probability Theory: Science sults, and probabilities, which The Logic of Science, Edwin are assigned based on experi- by E. T. Jaynes. G. Jaynes provides an answer and Larry Bretthorst, Ed. mental and theoretical informa- works out its repercussions for tion. Jaynes makes the case scientists confronted with data Cambridge University (correctly, I think) that rather from their experiments and ob- Press, New York, 2003. than worrying about subjectivi- servations. Jaynes is a Bayesian: 757 pp., $60, £45. ty, we need to think of probabil- ISBN 0-521-59271-2. he holds that probabilities en- ities as irrevocably conditional: code degrees of and do they can only be assigned based not exist except as a representation of in- on . The probability (P) of formation about the world. For some, this some (A) depends on back- position means that a Bayesian view of ground information (I) and is given by P(A|I). arises from the require- The reviewer is in the Astrophysics Group, Blackett ment that the same information I will lead Laboratory, Imperial College, Prince Consort Road, to the same probability assignment and London SW7 2AZ, UK. E-mail: [email protected] thus the same inference.

www.sciencemag.org SCIENCE VOL 301 5 SEPTEMBER 2003