Rohault, Jacques (1618–1672)

Summary

Born at Amiens, Rohault studied in the Jesuit college of his home city and then moved to Paris, where he became known as a professor of mathematics. He was the son-in-law of Claude Clerselier, the editor of Descartes’ unpublished writings, and as a result of this connection became a lightning rod of the Cartesian movement in France. Besides hosting some of the most famous Parisian conferences of his time – “the Wednesday meetings” – Rohault got actively involved in the dissemination of Cartesianism by sending Pierre-Sylvain Régis to teach Descartes’ philosophy in Toulouse. From the philosophical point of view, he presents his achievements as a combination of Aristotle's and Descartes’ thought, to which he adds something new, namely an experimental methodology.

Rohault published only two books during his life: the Traité de physique (1671a) and the Entretiens sur la philosophie (1671b). While the first aims at providing a textbook on natural philosophy, the second represents his answer to the increased debates about transubstantiation in France during the 1660s. More metaphysical in character, the Entretiens represents Rohault's contribution to the debate over forms and accidents. Relying on a Cartesian theory of matter, he appeals to Scholastic explanation in terms of matter, form, and privation. However, even if his taxonomy might look traditional, Rohault is very Cartesian in his explanation. He reduces the three Aristotelian principles of matter, form, and privation to simple properties of matter, something that is much better clarified by his Traité (see form, substantial).

More systematic in structure, the Traité de physique was a very influential book from its publication up to the middle of the eighteenth century, in France and elsewhere, including Louvain, Cambridge, and Utrecht. Quickly translated and published in Latin, this book was significant for the evolution of mechanical philosophy even in the context of the birth and development of Newtonianism. Moreover, in England, numerous editions of Rohault's treatise were accompanied by annotations from the celebrated Newtonian, Samuel Clarke. Varying in length and theme, Clarke's notes contribute to a range of debates in natural philosophy, by pointing out both the strengths and the weaknesses of Rohault's Cartesian solutions.