Pierre Gassendi

French scientist, philosopher, and religious leader

• Born: January 22, 1592
• Birthplace: Champtercier, Provence, France
• Died: October 24. 1655
• Place of death: Paris, France

Although best known for his Christianization of Epicurean atomism, Gassendi also advanced science through his discoveries in physics and astronomy, and he promoted Catholicism through his pastoral and administrative work.

Early Life

Pierre Gassendi (pyehr gah-sahn-dee) was born in a Provençal village in the south of France. His father, Antoine Gassendi, was a peasant farmer, and his mother, Françoise (Fabry) Gassendi, came from similar provincial roots. The mental abilities Pierre manifested as a child convinced his parents that he was not suited to farm labors, and his uncle, Thomas Fabry, the village priest, took care of his early education.

From the age of seven to fourteen, Pierre attended schools at Digne and Riez, neighboring towns to the east and south of Champtercier. After leaving school he spent two years on his father’s farm while teaching rhetoric at Digne. He resumed his formal education in 1609 at Aix-en-Provence, where he studied philosophy and theology. In 1612, he returned to Digne to teach theology. Having decided to become a priest, he traveled to Avignon and received his doctorate in theology in 1616. Shortly thereafter, he was ordained to the priesthood and said his first Mass.

For the next six years Gassendi taught philosophy at the university in Aix-en-Provence. During this time he began making the astronomical observations that would continue for more than three decades and constitute more than four hundred pages of his collected works. For example, in 1621, he observed luminous, multicolored, and shifting shapes in the northern sky, to which he gave the name “aurora borealis.” On his travels around France he met influential intellectuals and learned from them new scientific and philosophical ideas. Particularly important was his association with Nicolas-Claude Fabri de Peiresc , the priest, politician, and Humanist who became Gassendi’s friend and patron.

Life’s Work

Gassendi saw his life’s task as reconciling Christianity and science by resurrecting an ancient atomic theory and making it compatible with his deeply held religious convictions. In his first book, Exercitationes paradoxicæ adversus Aristoteleos (1624; unwelcome essays against the Aristotelians), he was highly critical of Aristotle’s claim to know the essences of things. For example, Aristotle reasoned from the nature of sound to the conclusion that high tones travel more rapidly than low tones, but seventeenth century scientists discovered that a sound’s velocity was independent of its pitch. In contrast to the authoritarianism of the Aristotelians, Gassendi favored a middle way between dogmatism and skepticism, in which genuine scientific knowledge arose from the astute description of phenomena. During the 1620’s, Gassendi visited Paris and deepened his friendship with Marin Mersenne , a Minim friar who was a proponent of the new science and a foe of the occult sciences. Gassendi, too, became an opponent of astrology, alchemy, divination from dreams, and natural magic.

When the Jesuits took over the university at Aix-en-Provence, Gassendi returned to Digne where, for the next several years, he devoted himself to his clerical duties, his scientific studies (by using the newly invented telescope, microscope, and barometer), and his philosophical and theological inquiries. He corresponded with Galileo, whose Copernicanism he shared. He also traveled to Paris, Flanders, and Holland, where he met many leading scholars and scientists. François Luillier, a government official, sometimes accompanied Gassendi, and he became another of his important patrons.

Throughout the 1630’s, Gassendi made many astronomical observations. Particularly important was his telescopic observation of Mercury crossing the face of the Sun in 1631. He was the first to see this transit of Mercury, and in his Mercurius in sole visus (wr. 1632; Mercury seen in the Sun; pb. 1658 in his Opera omnia) he used his data to support the heliocentric systems of Copernicus and Johannes Kepler , although, like Galileo, he was critical of Kepler’s theory of elliptical planetary orbits.

By this time Gassendi had become convinced that the only way to solve the skeptical crisis confronting Christianity was through the atomic theory of Epicurus, a Greek philosopher who had lived three centuries before the time of Christ. Gassendi once stated that he chose Epicurus as his exemplar because his system of the world could be more easily consolidated with Christianity than any other ancient philosophy. Epicurus was an unlikely choice, since this polytheist believed in a purposeless and uncreated universe inhabited by humans with mortal souls, whereas Gassendi, a believer in Divine Providence and the immortal human soul, understood that God had created a purposeful world composed of a finite number of atoms whose properties and aggregations accounted for all natural phenomena. Peiresc and Luillier, Gassendi’s patrons, supported his attempt to Christianize Epicurean atomism, but Peiresc’s death in 1637 had a devastating effect on Gassendi. Setting aside his studies of Epicureanism, he devoted himself to writing a biography of his friend, which was published in 1641.

Returning, in the 1640’s, to his scientific work and ecclesiastical duties, Gassendi traveled to Paris and taught philosophy to the nineteen-year-old Jean-Baptiste Poquelin, who would later become the famous playwright Molière. In 1642, he published a short work on motion that contained the first correct statement of the principle of rectilinear inertia, that is, the tendency of an object to remain in motion in a straight line. At the request of Mersenne, Gassendi published, in 1644, a critique of René Descartes’s Meditationes de prima philosphia (1641; Meditations on First Philosophy , 1680). Contrary to Descartes, Gassendi believed that, regardless of how clear and distinct ideas were, there was no guarantee that they represented anything real. Furthermore, Gassendi disagreed with the Cartesian identification of matter with extension, and he opposed Descartes’s theory of a voidless universe filled with matter, since Gassendi needed empty spaces for atomic motions.

Mersenne died in 1648 and Gassendi’s own health declined. He returned to Provence where he continued his work on science and Epicurean philosophy under the patronage of Henri-Louis Habert de Montmor. In Provence and, after 1653, in Paris, he wrote biographies of the astronomers Copernicus, Brahe, Regiomontanus, and Georg von Peurbach. He also reinterpreted Epicurean ethics in a Christian way. Epicurean hedonism sought to maximize pleasures and minimize pains, but for Gassendi the greatest pleasure attainable by a human being was the beatific vision of God, attainable after death only if individuals followed the rules of Christian morality. He did not live to see the publication of his chief work, Syntagma philosophicum (published in his Opera omnia, 1658). The disease from which he suffered, most likely tuberculosis, weakened his health, and he died at the home of Lord Montmor in 1655. Three years after his friend’s death, Montmor had all of Gassendi’s works published in six volumes.

Those scholars who admire Gassendi see him as laying the foundations of modern scientific thought. Though his contributions to science were not on the same level as those of Galileo, Kepler, or Newton, he performed some interesting experiments, such as analyzing falling objects from the mast of a moving ship, and he did introduce some important scientific ideas, such as rectilinear inertia, which went beyond Galileo’s erroneous circular inertia. Furthermore, by avoiding the dogmatism of the Cartesians and the nihilism of the skeptics, he devised a reformed atomism acceptable to both Christians and scientists.

Critics of Gassendi argue that his reformed atomism did little to stimulate new observations and experiments. Karl Marx, the nineteenth century materialist and socialist, characterized Gassendi’s attempt to Christianize atomism as cloaking a courtesan in a nun’s habit. However, a few scholars see Gassendi as a cryptomaterialist, whereas some Catholic scholars see a contradiction between his strong empiricism (nothing is in the mind that is not first in the senses) and his belief in an immaterial, immortal soul (how did such an idea get into the mind?).

Despite these differences, general agreement exists about Gassendi’s importance to seventeenth century thought. To many Christians, including some influential Jesuits, Gassendism was preferable to Cartesianism as an alternative to Scholasticism. To Protestants such as John Locke and Thomas Hobbes , Gassendi’s empiricism, hedonistic ethics, and theory of the social contract were important influences on their political theories. Gassendi’s ideas also influenced such scientists as Robert Boyle , Isaac Newton , and John Dalton. His contemporaries, especially those who knew him best, testify that he was comfortable with his Catholicism. Like the priest-scientist Pierre Teilhard de Chardin in the twentieth century, who Christianized evolution, Gassendi, through the cross-fertilization between his natural and supernatural milieus, created new views concerning Humanism, religion, and science that helped to create the intellectual foundations of the modern Western world.

Bibliography

Lindberg, David C., and Ronald L. Numbers, eds. When Science and Christianity Meet. Chicago: University of Chicago Press, 2003. This book emphasize the complexity of the relationship between science and Christianity throughout history, and William B. Ashworth, Jr.’s, essay, “Christianity and the Mechanistic Universe,” shows how Gassendi’s life and work was an important part of this story in the seventeenth century. Includes a further-reading guide and an index.

Osler, Margaret J. Divine Will and the Mechanical Philosophy: Gassendi and Descartes on Contingency and Necessity in the Created World. New York: Cambridge University Press, 1994. Osler argues that the differences between Descartes and Gassendi grew out of their different theological presuppositions. Includes an extensive bibliography and an index.

Sarasohn, Lisa T. Gassendi’s Ethics: Freedom in a Mechanistic Universe. Ithaca, N.Y.: Cornell University Press, 1996. In this analysis of the relationship between Gassendi’s natural philosophy and his ethics, Sarasohn shows how Gassendi found a middle way between Hobbesian materialism and Cartesian rationalism. Index.