Thomas Hobbes based his natural philosophy on definitions and general principles of matter in motion, which he refrained from calling “laws of nature.” Across the channel, René Descartes had presented his own account of matter in motion in such a way that laws of nature play a central causal-explanatory role. Despite some notable differences in the two systems of natural philosophy, the content of the three Cartesian laws of nature is shared by Hobbesian principles of motion. Why is it the (...) case that Hobbes never ‘transferred’ the concept of law of nature from the sphere of civil society to the realm of nature? What is the status of the Hobbesian principles of motion if they are not laws? Answering these questions is the main aim of this article. It is shown that Hobbes made available an importantly different and genuinely original way to do natural philosophy, which renders it free of metaphysics and eschews the need to ground it in anything other than ‘natural reason’. Briefly put, Hobbes took the category of ‘laws of nature’ to involve commitments that cannot be met in the natural world, unless natural philosophy loses its autonomy from theology and metaphysics. (shrink)