Abstract
I argue that thought experiments are a form of experimental reasoning similar to real experiments. They require the same ability to participate by following a narrative as real experiments do. Participation depends in turn on using what we already know to visualize, manipulate and understand what is unfamiliar or problematic. I defend the claim that visualization requires embodiment by an example which shows how tacit understanding of the properties of represented objects and relations enables us to work out how such objects might behave in a postulated world. This knowledge is that of embodied agents. That thought experiments require embodied participation is what makes them experiments rather than arguments. Unlike real experiments, from which ordinary perception has been displaced by instrumentation, thought experiments still appeal to relatively unmediated common sense, even when their purpose is to criticize or subvert common sense notions.