This paper argues that the metarepresentational structure of imagination plays a constitutive, epistemically active role in thought experiments. Against the propositional view defended by Salis and Frigg (2020), according to which only propositional imagination is necessary for performing thought experiments, I maintain that different varieties of imagination, objectual, perceptual, simulative, and affective, are essentially involved in thought experimentation. Drawing on Voltolini’s (2021) metarepresentational theory of fiction, I propose that thought experiments operate through a specific metarepresentational state involving make-beliefs, genuine beliefs entertained in fictional contexts. I defend two connected claims. First, metarepresentation is not merely an enabling background for imaginative engagement in thought experiments: it actively regulates the interface between fictional and real evaluative contexts. Second, this regulatory role becomes visible once we recognize a distinctive failure-mode, metarepresentational collapse, that cannot be captured in terms of incoherence or defective inference. This argument provides independent grounds for recognizing the theoretical autonomy of metarepresentation in the epistemology of thought experiments.
