Human and computer reasoning

Abstract

This paper reviews three main sorts of computer program designed to make deductive inferences: resolution theorem-provers and goal-directed inferential programs, implemented primarily as exercises in artificial intelligence; and natural deduction systems, which have also been used as psychological models. It argues that none of these methods resembles the way in which human beings usually reason. They appear instead to depend, not on formal rules of inference, but on using the meaning of the premises to construct a ‘mental model’ of the relevant situation, and on searching for alternative models of the premises that falsify putative conclusions. Experimental evidence corroborates this account of human reasoning.