The ‘If’ in the ‘What If’

In this paper, I defend the view that any good account of the logical form of thought experiments should contain a conditional. Moreover, there are some reasons to think it should be a counterfactual conditional. First, I defend Williamson’s account of the logical form of thought experiments against a competing account offered by Ichikawa and Jarvis. The two accounts have a similar structure, but Williamson’s posits a counterfactual conditional where Ichikawa and Jarvis’ posits a strict conditional. Williamson’s motivation is related to the problem of deviant realizations, and Ichikawa and Jarvis propose to take care of this problem by enriching the content of the thought experiment in the way we enrich the content of a text of fiction. However, this sort of enrichment is also compatible with Williamson’s account. I then consider a different view, defended by Malmgren, on which a complex possibility claim exhausts our reasoning on typical thought experiments. I argue that this account, leaving out a conditional, fails to represent an important part of our reasoning with thought experiments. This is brought out by reflection on the relationship between thought experiments and similar actual cases and by reflection on the requirement, formulated by Malmgren herself, that our reasoning should have an adequate level of generality.