Both in the Introduction to the Treatise of Human Nature and in the, Hume expressly declared that his goal was to contribute to the development of a “science of man” methodologically akin to the natural sciences, and capable of emulating their “accuracy” and explanatory success. He regarded these sciences as starting from careful observation of phenomena, and proceeding to the establish-ment of “principles” of increasing generality. Although rejecting as vain any hope of discovering “the ultimate principles” of any science, he (...) did not make clear what exactly he thought the principles actually involved in natural philosophy are. This article aims to shed some light on this issue through a survey and examination of the principles of Hume’s “science of man”, and of the most representative examples of principles of natural philosophy considered by Hume. (shrink)