Abstract
In her second edition of the Foundations of Physics, Du Châtelet advocates a three-fold distinction of explanation: the metaphysical, the mechanical, and the physical. While her use of metaphysical explanation (i.e., explaining via the Principle of Sufficient Reason) has received some attention in the literature, little has been written about the distinction she draws between mechanical and physical explanations, including their demand, scope, and use in physical theorizing. This paper aims to fill this void, arguing that making this distinction is a crucial piece of Du Châtelet’s scientific method. According to Du Châtelet, a mechanical explanation is one that ‘explains a phenomenon by the shape, size, situation, and so on, of parts’, whereas a physical explanation is one that ‘uses physical qualities to explain (such as elasticity) … without searching whether the mechanical cause of these qualities is known or not’ (Du Châtelet 1742, 181). I will analyze Du Châtelet’s views regarding (1) What counts as a good physical explanation, (2) Why a mechanical explanation is not necessary for answering most research questions in physics, and (3) Why a good physical explanation, instead, is sufficient for answering those questions. In so doing, I argue that Du Châtelet is proposing an independent criterion of what counts as a good explanation in physics: on the one hand, it frees physicists from the methodological constraint imposed by mechanical philosophy, which was still an influential school of thought at her time; on the other, it replaces this constraint with the requirements of attention to empirical evidence, for that alone determines which physical qualities are apt to serve as good explanans.
