The temporal negation suspension strategy in negative conditionals.

Abstract

In the psychology of reasoning, researchers have studied which conclusions follow from negative premises (it is not the case), providing in their tasks the choice of affirmative conclusions (it is the case) only. We thought this practice could mask a potential preference for negative conclusions, and indeed, the results of our experiments have corroborated our hypothesis. After reading negative conditional 'if-then' (Experiment 1) or negative biconditional (Experiment 2) statements - for example, 'it is not the case that if/if and only if A, C' - participants preferred to infer the negative conclusion 'it is not the case that A and C' over affirmative conclusions like 'it is the case that if/if and only if A, not-C' (the small-scope interpretation) or 'it is the case that A and not C' (the large-scope interpretation). These results support the idea that whenever people encounter the negation of a conditional or biconditional assertion, they temporarily suspend the negation, flesh out the possibilities of the corresponding affirmative assertions, and then incorporate the negation into the final conclusion. Experiment 3 used the negative conditional 'only if' and ruled out whether this finding can be explained by the matching bias. These results are discussed in the context of current theories of reasoning.