Causal judgments approximate the effectiveness of future interventions
When many things contributed to an outcome, people consistently judge certain ones to be more causal than others. For instance, people believe that a fire was more caused by the lit match than by the surrounding oxygen that fueled it. Why? Here, we offer a functional account of such patterns in causal judgment: By selecting causes as people naturally do, repeated judgments of whether something (e.g. the match) was the cause of an outcome (e.g. the fire) can be averaged to obtain the probability that introducing those things would produce the outcome (e.g., that lighting a match would start a fire). In other words, token causal judgments accumulate evidence about the general effectiveness of potential future interventions. We offer a formal account of this process, and show how it explains three basic qualitative features of causal judgment: why the causes people select tend (1) to be necessary, (2) to be abnormal, and (3) to lack abnormal counterparts.