In 1811 Hans-Christian Ørsted introduced the word “Tankeexperiment” as a technical term, while reflecting on Immanuel Kant’s Metaphysical Foundations of Natural Science. A hundred years later, Ernst Mach coined the term “Gedankenexperiment” for philosophical debate. Yet, serious investigation into thought experiments began only in the 1980s. A number of accounts have been proposed since then, ranging from platonism to eliminative empiricism. In this course we will examine these accounts, and explore many of the paradigmatic thought experiments.