What Underlies the Assessment of Conditionals?

According to some theorists, the strength of a conditional statement is determined solely by the extent to which the conditional’s antecedent is sufficient for its consequent. On this view, the strength of conditionals is independent of the degree to which the antecedent is necessary for the consequent. Data from four experiments reported here demonstrate that when people evaluate conditionals, they are also sensitive to whether the antecedent is necessary for the consequent. Conditionals are perceived as stronger the more necessary the antecedent is for the consequent. We discuss the implications of these results for theories of the meaning of conditional statements.