So How Does the Mind Work? - Steven Pinker

1 So HowDoesthe mind Work? Steven PINKERA bstract:In my bookHow the mind Works, I defended the theory that thehuman mind is a naturally selected system of organs of computation. Jerry Fodor claimsthat the mind doesn t work that way (in a book with that title) because (1) TuringMachines cannot duplicate humans ability to perform abduction (inference to the bestexplanation); (2) though a massively modular system could succeed at abduction, such asystem is implausible on other grounds; and (3) evolution adds nothing to our under-standing of the mind .

2 In this review I show that these arguments are flawed. First, myclaim that the mind is a computational system is different from the claim Fodor attacks(that the mind has the architecture of a Turing Machine); therefore the practicallimitations of Turing Machines are irrelevant. Second, Fodor identifies abductionwith the cumulative accomplishments of the scientific community over is very different from the accomplishments of human common sense, so thesupposed gap between human cognition and computational models may be , my claim about biological specialization, as seen in organ systems, is distinctfrom Fodor s own notion of encapsulated modules, so the limitations of the latter areirrelevant.

3 Fourth, Fodor s arguments dismissing of the relevance of evolution topsychology are 2000 Jerry Fodor published a book calledThe mind Doesn t Work That Way(hereafter:TMDWTW). The way that the mind doesn t work, according to Fodor,is the way that I said the mind does work in my bookHow the mind Works(HTMW).1 This essay is a response to Fodor, and one might think its title might beYes, It Does! But for reasons that soon become clear, a more fitting title might beNo One Ever Said it calls the theory inHow the mind Worksthe New Synthesis.

4 It combinesthe key idea of the cognitive revolution of the 1950s and 1960s that the mindis a computational system with the key idea of the new evolutionary biology ofthe 1960s and 1970s that signs of design in the natural world are products ofthe natural selection of replicating entities, namely genes. This synthesis, some-times known as evolutionary psychology, often incorporates a third idea, namelythat the mind is not a single entity but is composed of a number of facultiesspecialized for solving different adaptive problems.

5 In sum, the mind is a systemSupported by NIH grant HD 18381. I thank Clark Barrett, Arthur Charlesworth, Helena Cronin,Dan Dennett, Rebecca Goldstein, and John Tooby for invaluable for Correspondence: Department of Psychology, William James Hall 970, HarvardUniversity, Cambridge MA : discussesHTMW together with a second book, Henry Plotkin sEvolution in mind (Plotkin, 1997), which is similar in approach. But Fodor focuses onHTMW, as will , Vol. 20 No. 1 February 2005, pp. 1 24.# , 9600 Garsington Road, Oxford, OX4 2DQ, UK and 350 MainStreet,Malden, MA02148, organs of computation that enabled our ancestors to survive and reproduce inthe physical and social worlds in which our species spent most of its who are familiar with Fodor s contributions to cognitive science butwho have not readTMDWTW might be puzzled to learn that Fodor begs to differso categorically.

6 The first major theme ofHTMWis computation, and Fodor,more than anyone, has defended what he calls the computational theory of mind :that thinking is a form of computation. The second major theme is specialization,and Fodor s most influential book is calledThe Modularity of mind , a defense ofthe idea that the mind is composed of distinct faculties rather than a single general-purpose learning device or intelligent algorithm. The third theme is evolution,the source of innate biological structure, and Fodor, like many evolutionarypsychologists, is willing to posit far more innate structure than is commonlyaccepted in contemporary philosophy and psychology.

7 So it is surprising thatFodor insists thatHTMWis wrong, wrong, wrong. Fodor and I must disagreeon how the concepts of computation, faculty psychology (specialization), andinnate biological organization should be applied to explaining the mind . Thisessay will be organized Concept of Computation inHow the mind WorksAccording toHTMW(pp. 24 27; chap. 2), mental life consists of information-processing or computation. Beliefs are a kind of information, thinking a kind ofcomputation, and emotions, motives, and desires are a kind of feedback mechanismin which an agent senses the difference between a current state and goal state andexecutes operations designed to reduce the difference.

8 Computation in thiscontext does not refer to what a commercially available digital computer doesbut to a more generic notion of mechanical rationality, a concept that Fodorhimself has done much to elucidate (Fodor, 1968; 1975; 1981; 1994).In this conception, a computational system is one in which knowledge and goalsare represented as patterns in bits of matter ( representations ). The system isdesigned in such a way that one representation causes another to come intoexistence;andthese changes mirror the laws of some normatively valid systemlike logic, statistics, or laws of cause and effect in the world.

9 The design of thesystem thus ensures that if the old representations were accurate, the new ones areaccurate as well. Deriving new accurate beliefs from old ones in pursuit of a goal isnot a bad definition of intelligence , so a principal advantage of the computationaltheory of mind (CTM) is that it explains how a hunk of matter (a brain or acomputer) can be has other selling points. It bridges the world of mind and matter,dissolving the ancient paradox of how seemingly ethereal entities like reasons,intentions, meanings, and beliefs can interact with the physical # motivates the science of cognitive psychology, in which experimenters char-acterize the mind s information structures and processes (arrays for images, treestructures for sentences, networks for long-term memory, and so on).

10 Sincecomputational systems can have complex conditions, loops, branches, and filterswhich result in subtle, situationally appropriate behavior, the CTM allows themind to be characterized as a kind of biological mechanism without calling tomind the knee-jerk reflexes and coarse drives and imperatives that have madepeople recoil from the very idea. Finally, mental life internal representationsand processes appears to be more lawful and universal than overt behavior,which can vary with circumstances.