How, whether, why: Causal judgments as counterfactual contrasts

How do people make causal judgments? Here, we propose a counterfactual simulation model (CSM) of causal judgment that unifies different views on causation. The CSM predicts that people’s causal judgments are influenced by whether a candidate cause made a difference to whether the outcome occurred as well as to how it occurred. We show how whethercausation and how-causation can be implemented in terms of different counterfactual contrasts defined over the same intuitive generative model of the domain. We test the model in an intuitive physics domain where people make judgments about colliding billiard balls. Experiment 1 shows that participants’ counterfactual judgments about what would have happened if one of the balls had been removed, are well-explained by an approximately Newtonian model of physics. In Experiment 2, participants judged to what extent two balls were causally responsible for a third ball going through a gate or missing the gate. As predicted by the CSM, participants’ judgments increased with their belief that a ball was a whether-cause, a how-cause, as well as sufficient for bringing about the outcome.