Roberval, Gilles Personne de (1602–1675)

Summary

Roberval was born as Gilles Personne in the small village of Roberval near Senlis, France. His father was a poor farmer or farmworker, and his mother is said to have given birth to him in a field. At the age of fourteen, his intelligence recognized, Gilles Personne was given instruction in mathematics and languages by a local priest. He later earned his living as an itinerant teacher of mathematics. After witnessing the siege of La Rochelle, he supplemented his mathematical knowledge through studies in fortification and ballistics. Arriving in Paris shortly afterward, in 1628, Roberval soon became a member of the circle around Mersenne and later of the Académie de Montmor. Around 1630 he was given permission to append “de Roberval” to his surname. In 1632 Roberval was appointed professor of philosophy at Collège de Maître Gervais in Paris, a small institution attached to the university, and he lived in austere rooms there until his death. He never married. Roberval competed successfully for the Ramus chair in mathematics at the Collège Royal and was appointed in 1634. Required by the statutes to submit to open competition every three years, he nonetheless kept this post until the end of his life.

Descartes and Roberval disliked each other intensely. Unimpressed by the Geometry, Roberval sent his critical comments to its author through their mutual friend Mersenne. Their animosity increased further when Roberval defended Fermat's method of tangents against criticism from Descartes (AT II 104–14). From this point onward, the two men engaged in dispute on many questions from methods for determining centers of gravity to the nature of space and body. When Roberval published what was purportedly the Latin version of a newly found Arabic script of a lost work of Aristarchus, but was in fact his own affirmation of the Copernican hypothesis, Descartes poured ridicule on the book. In particular, he noted that the supposed properties of matter were inconsistent with a spherical universe (AT IV 402).