Thought experiments play an important epistemic, rhetorical, and didactic function in Galileo’s dialogues. In some cases, Salviati, Sagredo, and Simplicio agree about what would happen in an imaginary scenario and try to understand whether the predicted outcome is compatible with their respective theoretical assumptions. There are, however, also situations in which the predictions of the three interlocutors turn out to be theory laden. Salviati, Sagredo, and Simplicio not only disagree about what would happen, but they reject one another’s solutions as question begging and sometimes even dismiss one another’s thought experiments as misleading or nonsensical.