 If scientific practice has room for thought experiments, then the question arises as to why we would want philosophical methodology to be more discriminatory in this respect. One reason that is often offered is that results of scientific thought experiments may be subjected to further empirical testing. Obviously, this can’t be done for philosophical thought experiments. But, it seems difficult to accept a categorical separation of science and philosophy along these lines. The 17th century saw some of the most brilliant practitioners of thought experimentation in Galileo, Descartes, Newton, and Leibniz, all of whom pursued the project of “natural philosophy.” And in our own time, the creation of quantum mechanics and relativity are almost unthinkable without the crucial role played by thought experiments, most of which relate to important philosophical issues that arise from these scientific theories. Besides, much of ethics, philosophy of language, and philosophy of mind is based on the results of thought experiments in a way that seems very similar to scientific thought experiments (though some might contest this), including Searle’s Chinese room, Putnam’s twin earth, and Jackson’s Mary the colour scientist. Philosophy, even more than the sciences, would be severely impoverished without thought experiments. These observations partly explain why it has been argued that a more “unified” account of thought experiments is desirable (see Boniolo 1997; Cooper 2005, pp. 329–330; Gähde 2000). Of course, it is important not to downplay the significant differences between the sciences and philosophy. But an account of thought experiments seems more powerful if it can do justice to the fact that not only in the sciences we find many of them.