A Logical Design for the Mind?

Abstract

Originally published in Contemporary Psychology: APA Review of Books, 1996, Vol 41(5), 448-450. The Psychology of Proof: Deductive Reasoning in Human Thinking (see record 1994-97433-000) stands out as the most substantial and sophisticated defense of the mental logic position in the history of the 'field'. In this book, Rips advances what he calls the deduction-system hypothesis: that all normal members of the human species are equipped with an innate and extensive set of deduction principles that govern how we reason, and that this natural deduction system forms the core of many-perhaps most-cognitive activities. Although he intends his theory to account for human deductive reasoning, he also argues that these deduction procedures may be, in effect, the "general purpose programming" (p. viii) language of the human cognitive architecture within which a variety of nondeductive cognitive processes could also be implemented. The reviewer discusses difficulties with the mental logic position that originally led it into disfavor. It is argued that any system that operates on representations solely on the basis of their logical form ought to be relatively insensitive to their content. It is concluded that the field of reasoning research is left with an apparent contradiction: As Rips's book argues, certain facts about human reasoning seem almost to demand the existence of a mental logic-yet accepting Rips's hypothesis that the mind operates according to a mental logic leads to other predictions that seem to be contradicted by other apparent facts. There may be several paths out of this predicament, but we are aware of only one: to accept, as Rips suggests, that our reasoning faculties include some procedures that map onto logical rules such as modus ponens, AND Elimination, universal instantiation,and so on; but also to accept what Rips rejects-that our reasoning faculties simultaneously include a battery of specialized inference procedures that respond to content types, procedures that do not correspond to logical rules but that coexist in the same system with them. (PsycINFO Database Record (c) 2005 APA, all rights reserved)

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