Throughout different versions of the Wissenschaftslehre J. G. Fichte uses the term ‘experiment’ in reference to his philosophical method. This paper presents an account of Fichte’s methodological understanding of experiments in philosophy and their role in the Grundlage der gesamten Wissenschaftslehre (1794/95). I show that Fichte in Part One and Two of the Grundlage describes and conducts a type of philosophical experiment that draws on key elements of Kant’s conception of an “experiment of pure reason” in the Critique of Pure (...) Reason. On this account, Fichte introduces the notion of a philosophical experiment to explain how the Grundlage can establish its foundational principles by virtue of a synthetic method. Moreover, I argue that Fichte in Part Two further distinguishes between explorative and demonstrative experiments, each serving a distinctive role in proving the possibility and reality of theoretical knowledge. By way of this reading, I arrive at new conclusions concerning Fichte’s conception of the synthetic procedure to be employed in philosophy and the argumentative strategies employed in the Grundlage. (shrink)