The essay "Physique de croyant" is an important statement of Pierre Duhem's position on the relation between his science and his religion. Duhem trod a difficult path, some might say an impossible one, in Republican France because he was both a physicist and a devout Catholic. In this essay, using "Physique de croyant" as a touchstone, I explore the way in which he tried to reconcile his conflicting allegiances. There are several strands in Duhem's strategy that need to be teased (...) out. First, Duhem sought to defend his science against the charge that it was materialist and atheist. He did this with his claim, usually called the autonomy thesis, that physics and metaphysics are fundamentally different enterprises—that physics, properly conducted, has no metaphysical implications and requires no metaphysical support. This did not deny metaphysics its rightful territory. Second, Duhem used his segregationist position to defend the Roman Catholic Church against the assaults of the positivist scientism then in favor with the Republicans. Third, he also sought to protect his science against fellow Catholics who wanted to use it for polemical purposes. I develop and evaluate these lines of defense. (shrink)

From 1873 to 1878, the American physicist Josiah Willard Gibbs offered to the scientific community three great articles that proved to be a milestone for the science of thermodynamics. On the other hand, between 1886 and 1896, the French physicist Pierre Maurice Marie Duhem translated thermodynamics into the language of Lagrange’s analytical mechanics. At the same time, he expanded its scope to include thermal phenomena, electromagnetic phenomena, and all kinds of irreversible processes. Duhem formulated a version of thermodynamics characterized by (...) the conceptual unification of mechanics, physics, and chemistry. Overall, the work of both physicists on thermodynamics is tremendous, full of axioms, theorems, corollaries, proofs, and hundreds of equations. Therefore, it would be a utopian aim to provide a short analysis of their work. Instead, the present study will attempt to give a brief outline of the main tools and concepts used by the two physicists. I will argue that each scientist approaches thermodynamics in a new and unique way, which reveals their scientific styles as reflected in their personalities, the writing styles, their behavior toward publicity, and their inclination for publication. Finally, I will examine the influence of their theories on the development of chemical thermodynamics. (shrink)