Suppositions, Conditionals, and Causal Claims

Causal conditional statements such as 'if I work hard then I will get a first class degree' are comprised of an effect described in the consequent clause of the conditional (getting a first class degree) and a putative cause described in the antecedent clause (working hard). According to the suppositional theory (Evans, Over, & Handley (2005)), people evaluate causal conditional claims by supposing the cause and running a mental simulation in order to see whether the effect follows. In two experiments, using methods that have been employed to test this account, we examine the extent to which simulations of causepresent and cause-absent cases underlie evaluations of causal conditionals, concessive (even-if) conditionals and the strength of the causal relationship expressed by conditional claims. Whereas simulation of cause-present cases was positively associated with all three types of evaluation, simulation of cause-absent cases was negatively related to evaluations of the strength of the causal relationship expressed by a conditional claim, positively related to evaluations of even-if conditionals, and only weakly related to evaluations of causal conditionals. These results suggest that evaluating explicit causal claims, or conditional constructions used to deny such claims, cues a process of simulation that involves imagining that the antecedent event is 'undone'. This is akin to the 'undoing' associated with the generation of counterfactual possibilities and results in a belief that contributes to causal judgements in line with covariation and counterfactual accounts of causality. These findings suggest a mechanism through which people get a sense of the strength of causal relations in the world.