This chapter explains why cognition (Erkenntnis) is its own kind of cognitive good, apart from questions of justification. I argue against reducing the work of thought experiments to their epistemological results, such as their potential to provide prima facie justification. As an apparatus for cognition, a thought experiment enacts the three core elements of Ørsted’s Kantian account: (1) it is a tool for variation; (2) it proceeds from concepts, and (3) its goal is the genuine activation or reactivation of mental processes. Cognition has two components: givenness and thought. I will show in this chapter how givenness and thought are both achieved through thought experiments.