CONDITIONAL REASONING - THE NECESSARY AND SUFFICIENT CONDITIONS

Five experiments investigated two theories of conditional reasoning. T he pragmatic schema theory posits that conditional reasoning is mediat ed by context-sensitive inference rules. According to the contextual c uing theory, inferences are based on a mental model that represents ne cessity and sufficiency relations. Both schematic relations and necess ity relations predicted responses on Wason's four-card selection task. In contrast, after the effects of perceived necessity had been partia lled out, schematic relations did not predict responses to either a co nditional arguments task, or a task in which subjects judged the simil arity of ''if then'' and ''only if'' statements. These findings questi on the assumption that reasoning is mediated by schematic rules, which presumably apply regardless of task. However, there was evidence to s uggest that both schematic variables and the availability of counter-e xamples may be important in evaluating necessity relations, suggesting an alternative role for schematic-based interpretations in reasoning.