The central claim of this chapter is that the opening chapters of Du Châtelet’s Foundations of Physics are primarily concerned with scientific method, most famously in her chapter on hypotheses. It is argued that Du Châtelet saw weaknesses in the methods offered by the Cartesians and the Newtonians, and that she proposed her alternative in order to overcome these weaknesses. It is argued that she proposed a two-pronged methodology, consisting of principles of our knowledge (primarily the principle of contradiction and the principle of sufficient reason) and empirical investigation, for the proper assessment of hypotheses in scientific theorizing. It is suggested that the metaphysical commitments introduced in the early chapters of the Foundations are a consequence of Du Châtelet applying her method to problems in the foundations of physical science.