Born at Boulogne (St. Bertrand), a village in the foothills of the Pyrenees, Bayle was well known throughout England, France, and Germany as an esteemed physician, inventor, and savant. He was author of some fourteen works spanning topics in medicine, philosophy, physics, anatomy, and biology. He was a strong exponent of experimentation and Cartesianism and a member of the famous Société des Lanternistes.

During 1665–71, Bayle met and worked with Pierre-Sylvain Régis, a student of Jacques Rohault, who was sent from Paris to offer courses on Cartesianism. Bayle's General Systeme of the Cartesian Philosophy appeared in 1669 and contains the first complete statement of Descartes’ system. It is adumbrated but complete; it includes topics ranging from metaphysics and logic to plants and animals. Of note, given Bayle's concern with the role of experience in science, is the inclusion of the three grades of sensory response from Descartes’ Sixth Replies (AT VII 436–38, CSM II 291–95) (see sensation).

By 1670, Bayle habitually opened the Cartesian conferences, lecturing on curious medical cases , such as his study of a twenty-five-year pregnancy. He believed that such “freaks of nature” play an important role in the progress of science, piquing the curiosity of the scientist and motivating him to tedious study. With the publication of Dissertationes medicae tres in 1670, Bayle's work and merit were recognized by the Royal Society of London and the Académie des sciences in Paris.

Bayle's Discourse on Experience and Reason (Lennon and Easton 1992) carries the subtitle: “In which it is shown the necessity of joining the two in physics, in medicine, and in surgery.” Bayle criticizes placing reason above experience and failing to draw on reason to identify causes. He praises Descartes’ genius for identifying causes while cautioning the lack of sufficient observations for conclusions concerning the movement of the heart and the function of the pineal gland.

In addition to his activities as reformer, teacher, scientist, and physician, Bayle served as adviser to the Parlement of Toulouse in 1681 when summoned to examine multiple cases of alleged demonic possession. Against the common superstitions of the townspeople, Bayle offered a naturalistic explanation, which carried the day.