Pierre Gassendi

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Pierre Gassendi (January 22, 1592 – October 24, 1655) was a French philosopher, scientist, astronomer, and mathematician, best known for attempting to reconcile Epicurean atomism with Christianity and for publishing the first official observations of the transit of Mercury in 1631.

Like many intellectuals during the first half of the sixteenth century, Gassendi sought an alternative to the Aristotelianism which had long been the foundation for natural philosophy. Gassendi was responsible for introducing the atomism of Epicurus into the mainstream of European thought, by modifying it to conform to the requirements of Christian theology. He applied his theory of atomism in a variety of scientific fields, including chemistry, astronomy, natural science, optics, and even psychology and education. Gassendi promoted the acquisition of knowledge by the empirical method, through experimentation and analysis. His Epicurean ethics, in which God endowed man with both free will and the desire for pleasure, influenced the writings of Thomas Hobbes and John Locke.


While rationalism or empiricism tended to eliminate mysticism and turn away from notions of God in later developments, Gassendi's own stance on defending man's empirical method of attaining knowledge while rooting his thought in spiritual values highlights Gassendi as a valuable thinker of his time.


Early Life

Gassendi was born January 22, 1592, at Champtercier, near Digne-les-Bains, in France. At a very early age he showed academic potential and attended the college at Digne, where he studied Latin and rhetoric and showed particular aptitude for languages and mathematics. Soon afterwards he entered the University of Aix-en-Provence to study philosophy under P. Fesaye.

In 1612, when he was 16, the college of Digne called him to lecture on theology. Four years later he received the degree of doctor of theology at Avignon, becoming proficient in Greek and Latin, and in 1617 he took holy orders. In the same year he was appointed to the chair of philosophy at University of Aix-en-Provence.

Gassendi lectured principally on the Aristotelian philosophy, conforming as far as possible to the orthodox methods. At the same time, however, he followed with interest the discoveries of Galileo Galilei and Johannes Kepler, and became more and more dissatisfied with Aristotelianism. The period of revolt against Aristotelianism had begun, and Gassendi shared the empirical tendencies of the age. He contributed to the objections of Aristotelian philosophy, but waited to publish his thoughts.


Gassendi was deeply faithful, but one motivation for his career in the church seems to have been to secure a steady livelihood. Gassendi began as a humble canon in Digne, and twenty years later had advanced only to the slightly more elevated post of provost. He maintained himself in the good graces of the church, while writing letters of support to Galileo and cultivating personal and intellectual relationships with his secular patrons, Francois Luillier, Nicole-Pierre Fabri de Peiresc, local count of Alais Louis Emmanuel de Valois, and Parisian noble Habert de Montmor.

To allow him leisure for his studies, he was appointed a canon (c. 1623) at the cathedral of Digne. After several years of teaching philosophy and theology, Gassendi distanced himself from the rigid teachings of the scholastics. In 1624, after he left Aix for a canonry at Grenoble, he printed the first part of his Exercitationes paradoxicae adversus Aristoteleos. A fragment of the second book later appeared in print at La Haye (1659), but Gassendi never composed the remaining five, apparently thinking that the Discussiones Peripateticae of Francesco Patrizzi left little scope for his labors.

Gassendi then began a formative partnership in physiological, astronomical, and historical studies with his wise and wealthy patron Peiresc, which he later described in a biography of Peiresc written, after his death, in 1637. He developed his interests in physics and in the atomism of Epicurus. His published work in philosophy and natural philosophy captured the attention of the Minim priest, Marin Mersenne.

After 1628 Gassendi traveled in Flanders and in Holland, the only time he left France. During this period he wrote, at the request of Marin Mersenne, his refutation of Robert Fludd’s mystical attacks on Robert Keppler (Epistolica Exercitatio, in qua precipua principia philosophiae Roberti Fluddi deteguntur, 1631); an essay on parhelia (Epistola de parheliis); and some valuable observations on the transit of Mercury which Kepler had foretold. He returned to France in 1631, and two years later became provost of the cathedral church at Digne.

Astronomical Observations

In 1631, Gassendi became the first person to describe the transit of a planet across the Sun, viewing the transit of Mercury, which Kepler had predicted, by using a Galilean telescope to project the sun’s image on a sheet of paper. In December of the same year, he watched for the transit of Venus, but this event occurred when it was night in Paris.

Controversy with Descartes

Gassendi then spent some years traveling through Provence with Charles de Valois, duke of Angoulême, governor of the region. During this period he wrote only one literary work, his Life of Nicolas-Claude Fabri de Peiresc, which has been reprinted numerous times and been translated into English. In 1641 he was sent to Paris for the assembly of French clergy, and taught philosophy to Jean-Baptiste Molière.

In 1642 Mersenne engaged him in controversy with René Descartes. His objections to the fundamental propositions of Descartes appeared in print in 1642; they appear as the fifth in the series contained in the works of Descartes. Gassendi subsequently published his rebuttals in his Disquistio Metaphysica of 1646.

Mathematics chairmanship

In 1645, on the recommendation of Cardinal Richelieu, Gassendi was appointed by the king to the chair of mathematics in the Collège Royal in Paris, and gave his inaugural lecture on November 23 in the presence of the cardinal. His lectures on astronomy were published in 1647 as "Institutio Astronomica." In addition to controversial writings on physical questions, there appeared during this period the first of the works for which he is remembered by historians of philosophy. In 1647 he published the well-received treatise De vita, moribus, et doctrina Epicuri libri octo. Two years later he published a commentary on the tenth book of Diogenes Laertius, De vita, moribus, et placitis Epicuri, seu Animadversiones in X. librum Diog. Laër. (Lyons, 1649; last edition, 1675), and in the same year he published the more important Syntagma philosophiae Epicuri (Lyons, 1649; Amsterdam, 1684).

In 1648 an inflammation of the lungs compelled him to give up his lectures at the Collège Royal. He traveled in the south of France -in company of his protégé, aid and secretary François Bernier, spending nearly two years at Toulon, where the climate suited him. In 1653 he returned to Paris and resumed his literary work, publishing in that year lives of Copernicus and of Tycho Brahe.

Death and Memorials

The lung complaint from which he suffered continued to trouble him, and one year later he fell seriously ill with intermittent fever. The doctors bled him fourteen times, as strength failed and his voice became a whisper. He died October 24, 1655 in an apartment in the Chateau de Monmort, and was buried in the chapel there.

A bronze statue of him was erected by subscription at Digne in 1852. The Moon's Gassendi crater is named after him.

After Gassendi's death, his general renown, his influence on French education and popular conceptions of natural science, and impact on the discussion of Descartes' legacy, increased. Montmor and Gassendi's other Parisian friends collected his manuscripts on Epicurean logic, the natural sciences, psychology, and ethics and arranged to have them published posthumously as Syntagma Philosophicum. In 1658 they published six volumes of collected works, the Opera Omnia (Lyon, 1658; Florence, 1727), which included the Syntagma together with many of Gassendi's other writings, including his correspondence, letters on optics and the free fall of bodies, and a portion of his voluminous astronomical observations. In 1674-1675 Gassendi's acolyte, François Bernier, published a condensed, abridged, reorganized, and occasionally paraphrased version of the Opera Omnia, written in French. Over the following half century, the “Gassendistes” stood as formidable opponents to the “Cartésiennes” in French debates over educational and scientific matters, and Gassendi's thinking spread—variously influencing Gottfried Leibniz, Robert Boyle, John Locke, and Isaac Newton, among others.

Thought and Works

Gassendi is most remembered for introducing the atomism of Epicurus into European thought, for his opposition to Aristotelianism, and for his debate with Descartes. However, his greatest contribution to natural science and philosophical thought may have been through his active participation in intellectual deliberations with many prominent thinkers of his age. Gassendi corresponded with Hobbes, Mersenne, and Christina of Sweden, and engaged in controversy with Fludd, Herbert, and Descartes. He promoted the empiricist method in scientific and speculative investigation.

His philosophical system, particularly as it is presented in the Syntagma Philosophicum, has often been characterized as eclecticism. In fact, Gassendi's philosophy was a fully-referenced scholarly enterprise, advancing new historical styles and rhetorical modes. His philosophical system represents a model of research and exposition which is still in philosophical use today, and his significance in modern thought has recently been re-examined in the context of the history of philosophy.

Gassendi became one of the first to treat the literature of philosophy in a lively way. His writings abound in those anecdotal details, natural yet not obvious reflections, and vivacious turns of thought, which made Edward Gibbon style him—with some extravagance, but also with some truth—as "Le meilleur philosophe des littérateurs, et le meilleur littérateur des philosophes" (“The best philosopher among writers, and the best writer among philosophers”).


Many European intellectuals during the first half of the seventeenth century sought an alternative to the Aristotelianism which had been the foundation for natural philosophy. Gassendi was responsible for introducing the atomism of Epicurus into the mainstream of European thought, by modifying it to conform to the requirements of Christian theology.

Like Epicurus, Gassendi taught that the universe is made up of indivisible elemental particles, atoms, moving in void space. However, Gassendi claimed that there was a finite number of these particles, that they had been created by God, and that therefore the resulting universe was rule by divine providence. Gassendi was not a materialist; he argued for the existence of an immaterial, immortal soul and believed in the existence of angels and demons. He also believed that God had the freedom to impose His will upon the Creation.

Gassendi developed his theories of atomism in a wide range of applications, not only in chemistry and physics but in all areas of natural science and even in the fields of psychology and education. His atomist theory of light, which he described as a property carried by particular atoms, provided an alternative to Descartes’ view of light as pressure. His theory was that sound also traveled in the form of particles, and he believed that the velocity of these sound particles was unaffected by wind or air quality. Even planetary motion was explained as being driven by magnetic forces borne by dedicated atoms (this was an atomist modification of a view developed, though later abandoned, by Kepler).

Skepticism and Empiricism

Gassendi accepted the skeptical doctrine that we cannot have certain knowledge of the real essences of things through our sensory perceptions. Instead, he argued that we can have knowledge of the way things appear through sensory experiences. Though this “science of appearances” can give us only probable, and not certain, knowledge, it can provide us with knowledge useful for living in this world.

Though a favorite maxim of Gassendi’s was "that there is nothing in the intellect which has not been in the senses" (nihil est in intellectu quod non prius fuerit in sensu); and though he characterized the imagination (phantasia) as a counterpart of the senses, essentially the same in man and animal, he admitted that the intellect attains notions and truths of which no effort of sensation or imagination can give us the slightest apprehension (Op. ii. 383). Examples of these notins were the concept of God as both corporeal and incorporeal, the concept of universality, and the mind’s ability to reflect on its own thought processes.


Gassendi promoted the Epicurean ethics of hedonism, but developed a Christianized concept of pleasure. He believed that God endowed man both with free will and an innate desire to experience pleasure. Human beings participated in God’s providential plans for the creation by exercising their freedom of choice in seeking pleasure. The greatest pleasure which a human being could experience was the beatific vision of God after death. Gassendi developed a political theory of social contract, which influenced the thinking of Hobbes and Locke.

Scientific Observations

Gassendi’s contribution to the revival of atomism was only one aspect of his scientific interests. In the field of physics he also conducted a study of bodies in free fall (closely modeled on Galileo's work), an elaboration of the principle of inertia, and an early and reasonably accurate interpretation of the Pascalian barometry experiments of the late 1640s. Gassendi also conducted a number of scientific experiments. He attempted to measure the speed of sound by cannon fire, arranged to have weights dropped from the mast of a moving ship to enact Galileo's thought experiment (and so dispel doubts about the motion of the Earth), and carried out numerous chemical trials involving, among other things, the dissolution of salts and formation of crystals. He offered a wide variety of speculations, shaped by his atomism, on the earth sciences, based partly on geological fieldwork and biological and physiological observations. Gassendi devoted much of his time to astronomy. For decades, he made regular observations of the skies for decades, producing confirmatory evidence for Kepler's views, observing sunspots, the anses (rings) of Saturn, successfully predicting an eclipse in 1654, and recording his famous observation of the passage of Mercury before the Sun (1631). He commissioned the first map of the Moon, defended the Copernican view as plausible except for its conflicts with the teachings of the Roman Catholic Church, and disparaged the practice of astrology.


Monmort published Gassendi's collected works, most importantly the Syntagma philosophicum (Opera, i. and ii.), in 1658 (6 vols., Lyons).

N. Averanius published another edition, also in six folio volumes, in 1727. The first two comprise entirely his Syntagma philosophicum; the third contains his critical writings on Epicurus, Aristotle, Descartes, Fludd and Lord Herbert, with some occasional pieces on certain problems of physics; the fourth, his Institutio astronomica, and his Commentarii de rebus celestibus; the fifth, his commentary on the tenth book of Diogenes Laertius, the biographies of Epicurus, Nicolas-Claude Fabri de Peiresc, Tycho Brahe, Copernicus, Georg von Peuerbach, and Regiomontanus, with some tracts on the value of ancient money, on the Roman calendar, and on the theory of music, with an appended large and prolix piece entitled Notitia ecclesiae Diniensis; the sixth volume contains his correspondence. The Lives, especially those of Copernicus, Tycho and Peiresc, received much praise.

Samuel Sorbière recounts Gassendi's life in the first collected edition of the works, by Joseph Bougerel, Vie de Gassendi (1737; 2nd ed., 1770); as does Damiron, Mémoire sur Gassendi (1839). An abridgment of his philosophy was given by his friend, the celebrated traveler, François Bernier (Abrégé de la philosophie de Gassendi, 8 vols., 1678; 2nd ed., 7 vols., 1684).

Surveys of his work include:

  • George Sidney Brett, Philosophy of Gassendi, (London, 1908)
  • Johann Gottlieb Buhle, Geschichte der neuern Philosophie, iii. 1, 87-222
  • Jean Philibert Damiron, Mémoires pour servir a l'histoire de philosophie au XVII siècle
  • Pierre-Félix Thomas, La Philosophie de Gassendi (Paris, 1889)


  • This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
  • Antonina, Alberti. (1988). Sensazione e realtà. Epicuro e Gassendi, Florence, Leo T. Olschki. ISBN 8822236084
  • Bloch, Olivier. (1971). La philosophie de Gassendi. Nominalisme, matérialisme et métaphysique. La Haye: Martinus Nijhoff. ISBN 9024750350
  • Fisher, Saul. (2005). Pierre Gassendi's Philosophy and Science. Leiden: Brill. ISBN 978-9004119963
  • Joy, Lynn Sumida .(1987). Gassendi the Atomist: Advocate of History in an Age of Science. Cambridge /New York: Cambridge University Press. ISBN 0521522390
  • Lolordo, Antonia. (2006). Pierre Gassendi and the Birth of Early Modern Philosophy. Cambridge/New York: Cambridge University Press. ISBN 978-0521866132
  • Messeri, Marco. (1985). Causa e spiegazione. La fisica di Pierre Gassendi. Milan: Franco Angeli. ISBN 8820440458
  • Osler, Margaret J. (1994). Divine Will and the Mechanical Philosophy: Gassendi and Descartes on Contingency and Necessity in the Created World. Cambridge/New York: Cambridge University Press. ISBN 0521461049
  • Puster, Rolf W. (1991). Britische Gassendi-Rezeption am Beispiel John Lockes. Frommann-Holzboog. ISBN 3772813623
  • Tack, Reiner (1974). Untersuchungen zum Philosophie- und Wissenschaftsbegriff bei Pierre Gassendi: (1592 - 1655). Meisenheim (am Glan): Hain. ISBN 3445011036

External links

All links retrieved December 6, 2013.

General Philosophy Sources


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