Pragmatic conditional reasoning: Context and content effects on the interpretation of causal assertions

Abstract

The present study investigates two kinds of background knowledge which affect interpretations of ‘If-then’ conditionals that assert a causal relation between an antecedent and a consequent. The first factor was the presence of contextual assertions which affirmed or denied the existence of alternative plausible causes in the backgrounded ‘causal field’ in which the target conditional was evaluated. It was predicted that subjects would be more likely to treat the target antecedent as sufficient and not necessary when the presence of an alternative plausible cause was affirmed, and less likely to do so if its existence were denied. The second factor was the extremity or rarity of the consequent event. It was hypothesized that more extreme or rare consequents would be more likely to be judged to have antecedents that are necessary and not sufficient. Both major hypotheses received substantial support in a conditional reasoning task. An innovative method of analysing subjects' responses is used which does not assume that subjects are reasoning according to a logical rule. This method is used to indicate systematic tendencies to apparent logical self-contradiction in subjects' responses, which may be associated with pragmatic factors. Finally, the relevance of the present results for various theoretical positions on the interpretation of conditional relations is discussed.