Kant did not distinguish between thought experiment (TE) and real-world experiment (RE), nor did he use the German term Gedankenexperiment. But he is of great importance in the history and theory of TEs. Many aspects of Kant’s critical philosophy are connected with the concept of TE, including the definition of scientific experiment, the distinction between knowing and thinking, and the fact that “experiments” of pure and practical reason embody the specific method of philosophy (Section 2).