Pierre Gassendi (b. 1592, d. 1655) was born at Digne, France, became a priest in 1617, and later a professor of philosophy at Aix while still in his mid-twenties. As Saul Fisher notes in his excellent Pierre Gassendi’s Philosophy And Science: Atomism for Empiricists (Brill, 2007), “Gassendi’s career as a priest is a crucial intellectual facet of intellectual constitution: his writings reflect an unbending allegiance to Holy Scripture and Church teachings, though not necessarily in orthodox doctrinal lights” (1.) In 1624, he met Mersenne, and between 1629 to 1630, while traveling in the Low Countries, he met Isaac Beeckman. In his 1632 work, Mercurius in sole visus, he described his 1631 observation of the transit of Mercury as a confirmation of Kepler’s theories. In 1632, after returning to Digne, he began a study of the ancient Greek philosopher Epicurus.
Gassendi spent the remaining twenty or so years of his life going between Provence and Paris due to his involvement with a group of philosophers who had gathered around the French philosopher Mersenne. As Fisher details, in the Mersenne circle, “debates ranged over numerous topics central to the dismantling of the Aristotelian and Scholastic world-views” (3.) Mersenne, an associate of Descartes, was instrumental in allowing Gassendi’s objection to Descartes’ Meditations to be included in the published appendix entitled Objections and Replies.
While some historians consider Gassendi’s signature achievement to be his revival of ancient atomism, a complete account of Gassendi’s philosophic and theological project, such as that produced by Saul Fisher, acknowledges that atomism was a only a portion of his anti-Aristotelianism. Gassendi preformed experiments investigating the behavior of bodies in free fall, experiments which closely mirrored those of Galileo. He also attempted to measure the speed of sound through an experiment involving cannon fire. As importantly, Gassendi produced numerous natural and geological histories and attempted to reconcile these histories with his atomism. In addition to his numerous astronomical observations, he commissioned the first map of the surface of the moon.
The later portion of his career saw the publication of studies on Epicurean philosophy as well as a Latin translation of Diogenes Laertiius’ volume on Epicurus, with commentary, in his Animadversiones of 1649. He continued elaborating his philosophic program until his death in the Paris apartment of Montmor in 1655.
Gassendi presents a particularly interesting problem of intellectual placement. His philosophic program was built upon a debate with classical authors and with the varieties of ancient and medieval Aristotelianism. Gassendi’s philosophy was as textual as it was experimental.
Although his skepticism and his empiricism are plausible supports for his scientific modernity, Gassendi’s recourse to atomism may be more correctly situated in the Greek revival associated with Renaissance humanism. Gassendi’s Latin and French were ornate and antiquarian. His works are replete with copious passages from Greek and Roman philosophers. If Descartes wished to inform his readers of his break from the classical tradition, Gassendi found it unproblematic to be in some instances continuous with it. For Gassendi, there was as much truth as error in the writings of the Stoics, Cynics, and Skeptics.
Gassendi, in another sense, was content to be placed among the ‘moderns.’ He subjected Aristotle’s natural philosophy and his causal view of the world to a rigorous empiricism. Along with Galileo, Gassendi argued for the factual failure of the Aristotelian doctrine of motion through a methodology which professed a reliance upon observation and experiment. While Bacon and Descartes both put forward a methodology for the adoption of a new science, only savants (Fisher’s term), such as Gassendi, cast aside the ontological argument and the grounding of phenomenology in necessity, essences, and clear and distinct ideas.
The removal of these elements and of the certainty they promised was the natural consequence of Gassendi’s rigorous defense of only two types of knowledge: revelation, concerning matters of faith and salvation, and sensory, concerning the properties of physical bodies, which could only be dimly perceived.
The most basic claim about the world that Gassendi made was that everything in it was contingent and the product of God’s will. As importantly, Gassendi argued, in opposition to Descartes, that if there was anything like an essence beneath the sensible, neither did it necessarily exist nor was it accessible to human understanding. In sum, Gassendi’s philosophic endeavor wedded a modern experimentalism to an epistemology and a phenomenology transmitted by an ancient tradition. Gassendi was between the ancients and the moderns – a blend of ancient theory and modern practice.