Strategies in syllogistic reasoning

This paper is about syllogistic reasoning, i.e., reasoning from such pairs of premises as, All the chefs are musicians; some of the musicians ore pain ters. We present a computer model that implements the latest account of syl logisms, which is based on the theory of mental models. We also report four experiments that were designed to test this account. Experiments 1 and 2 e xamined the strategies revealed by the participants' use of paper and penci l as aids to reasoning. Experiment 3 used a new technique to externalize th inking. The participants had to refute, if possible, putative conclusions b y constructing external models that were examples of the premises but count erexamples of the conclusions. Experiment 4 used the some techniques to exa mine the participants' strategies as they drew their own conclusions from s yllogistic premises. The results of the experiments showed that individuals not trained in logic con construct counterexamples, that they use similar operations to those implemented in the computer model, but that they rely o n a much greater variety of interpretations of premises and of search strat egies than the computer model does. We re-evaluates current theories of syl logistic reasoning in the light of these results.