INTERPRETATIONAL FACTORS IN CONDITIONAL REASONING

Two experiments examined the role of necessity and sufficiency relatio nships in conditional reasoning. The results indicated that perceived necessity and sufficiency predicted variability in reasoning performan ce for four pragmatic relations (permission, obligation, causation, an d definition), for both determinant and indeterminant syntactic forms, and for both a conditional arguments and a truth table evaluation tas k, as well as when the temporal relationship between the antecedent an d consequent events was reversed. These data support the general utili ty of perceived necessity and sufficiency in the interpretation and ev aluation of conditional relationships. However, the effects of necessi ty and sufficiency were smaller for reversed than for forward statemen ts, which suggests that necessity/sufficiency-based interpretations ma y be more useful for evaluating some types of conditional relations th an others. In addition, people were more likely to accept valid rather than invalid arguments, regardless of necessity/sufficiency relations , a finding that suggests that abstract, content-free representations may play a functional role in conditional reasoning.