Gassendi, Pierre (1592–1655)

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Pierre Gassendi, the leading French seventeenth-century skeptical and Epicurean philosopher and scientist, was born at Champtercier, a Provençal village in France. He studied at Digne and Aix-en-Provence and was appointed professor of rhetoric at Digne at the age of twenty-one. In 1614 he received his doctorate in theology at Avignon. He was ordained a priest in 1616 and was appointed professor of philosophy at Aix. From 1617 to 1623 he lectured on Aristotle's philosophy, developing a forceful critique of it. His first published work, Exercitationes Paradoxica Adversus Aristoteleos (1624), was intended to be followed by six more parts, of which only the second part, published posthumously, was written. It contains both an attack on Aristotle's thought and portions of Gassendi's mitigated skepticism.

After a year in Digne, during which he performed various ecclesiastical duties, Gassendi visited Paris for a brief period in 1625 and became friendly with such avant-garde thinkers as Francois de La Mothe le Vayer and Marin Mersenne. He continued the astronomical researches that he had begun in Provence, and, with the mathematician Claude Mydorge (15851647), observed a lunar eclipse. Gassendi's careful astronomical records from 1618 to 1655 were published after his death. He also engaged in many scientific studies with his patron, Nicolas-Claude Fabri de Pieresc (15801637). His discovery of the perihelion of Mercury was an important support for the Copernican theory at the time.

Gassendi returned to Paris in 1628, remained there until August 1629, and then spent nine months in Flanders and Holland, where he met many leading scientists and scholars. He spent the next years partly in Paris and partly in Provence, publishing scientific works on astronomy and physics and presenting skeptical attacks on Herbert of Cherbury and the Rosicrucian Robert Fludd. He undertook an intensive study of Epicurean atomism, a subject in which he had been interested for some time. The results of this study were to form a basic part of his later writings.

In 1634 Gassendi was elected provost of the Cathedral of Digne. In 1641 he was sent to the assembly of the French clergy in Paris and during this visit taught philosophy to the young Molière (16221673). Gassendi was appointed to the chair of mathematics at the Royal College (now the Collège de France) in 1645, but because of ill health he was away from his post from 1648 to 1653. He fell ill in 1654 and died the following year.

Except for his early attacks on Aristotelianism, Fludd's Rosicrucianism, and Herbert of Cherbury, Gassendi's philosophical works date from the 1640s onward. In 1641, at the request of Mersenne, Gassendi wrote his objections to René Descartes's Méditations ("Fifth Set of Objections"). Descartes's testy answer led Gassendi to expand his criticism into the bulky Disquisitio Metaphysica, finished in 1642 and published in Amsterdam in 1644. He published three works on Epicurus and his philosophy between 1647 and 1649: De Vita et Moribus Epicuri (1647), Animadversiones in Decimum Libri Diogenis Laertii, qui est de Vita, Moribus Placitisque Epicuri (1649), and Syntagma Philosophiae Epicuri, cum Refutationibus Dogmatum, Quae Contra Fidem Christianum ab eo Asserta Sunt (1649). His most important philosophical writings appeared only posthumously, in the 1658 edition of his complete works. His overall treatment of philosophical problems appears in Syntagma Philosophicum (Opera, volumes 1 and 2) and in the second part of his first work, the Exercitationes, which presents his constructive or mitigated skepticism.


Gassendi's thought developed from a fairly thoroughgoing skepticism, strongly influenced by Sextus Empiricus, Michel Eyquem de Montaigne, Pierre Charron, and Francisco Sanches, to what he called a via media between skepticism and dogmatism. The via media involved both a fundamental epistemological skepticism and a hypothetical form of Epicurean atomism that was modified to eliminate those aspects of Epicurus's thought that conflicted with Christian doctrine. In the first part of the Exercitationes Gassendi, following in the tradition of Francesco Patrizi and Peter Ramus, tried to show all the erroneous or dubious aspects of Aristotelianism. The second part set forth an attack on all those who claimed to have discovered necessary and indubitable knowledge of the real nature of things. Our knowledge of the world, Gassendi insisted, comes only from sensory experience. We are unable to arrive at absolutely true first principles and real or essential definitions, since inductions from experience can never yield certain universal prepositions. No matter how much data are gathered, a negative instance may still turn up in the future. Even if we somehow managed to discover some genuine definitions and first principles, no further scientific knowledge about nature could be gained by employing syllogistic reasoning, since, as the Greek Pyrrhonists had shown, the truth of the premises of a syllogism depends on antecedent knowledge that the conclusion is true. Either the conclusion is part of the evidence of the premises or the syllogism establishes nothing, since it is not known whether the premises are true.

In the concluding section Gassendi launched his strongest attack on the possibility of gaining necessary knowledge about the world. Using the arguments of the ancient skeptics, he tried to show that all that we can know is how things appear, not how they really are in themselves. We can know that honey seems sweet, but we cannot find out if it really is sweet. On the basis of appearances we cannot tell what the real nature of things must be that produces such effects on us. Sense experience varies too much to provide any means for determining what reality is like on the basis of what is perceived. We lack any means of reasoning from experience to what has caused it. We are not even able to establish any criterion of true knowledge. Hence, we can only conclude that nothing can be known about reality. However, in this early work Gassendi insisted that we can develop useful sciences about appearances. As long as we restrict our conclusions to the world of experience, we will neither come in conflict with divine truth, nor accept any dubious dogmatic theory about unperceived reality. Such theories, whether metaphysical or mathematical, are presumptuous conjectures that have no value whatsoever.

Objections to Descartes

In his middle period Gassendi challenged those who claimed to have discovered some means of knowing the real nature of things. He employed various skeptical arguments against Renaissance naturalists and against such leading "new philosophers" as Herbert of Cherbury and Descartes. Gassendi's two letters against Herbert's De Veritate (in which the latter claimed to have refuted skepticism) used arguments about diversity of experience and disagreements among individuals to counter Herbert's common notions and common consent theory. In the "Fifth Set of Objections" and the Disquisitio Metaphysica, Gassendi turned skeptical argumentation against Cartesianism. He tried to show that Descartes's method of doubt illustrated what the skeptics had claimed for centuries. Then Gassendi challenged Descartes's positive dogmatic conclusions. Gassendi contended that the vaunted Cartesian criterion of true knowledge (that of clarity and distinctness) was useless, since people often think that they clearly and distinctly perceive something and then turn out to be wrong. Hence, to employ this criterion, another criterion would be needed to determine when something really is clear and distinct and does not merely appear to be so. In addition, another criterion would be necessary to employ this second criterion, and so forth.

The culmination of Gassendi's attack, which Descartes called the objections of objections, was his posing the possibility that all knowledge, even if it were clear and distinct, might not be about anything outside of our minds. If this could be the case, then all the knowledge purported to be found by Descartes might be imaginary or fictitious. Descartes saw this suggestion as a fundamental challenge to his system and as a denial of the possibility of gaining knowledge about any reality other than our own thoughts. His reply consisted in refusing to take the objection seriously, since if one did, "it follows that there is nothing that we can in any way comprehend, conceive or imagine, that should be accepted as true, that is to say that we have to shut the door completely on reason, and be content to be monkeys, or parrots, and no longer men" (Descartes, Oeuvres, C. Adam and P. Tannery, eds. vol. IXA, 212).

Mitigated Skepticism

In his later writings Gassendi attempted to develop a mitigated skepticism that would show how we could possess worthwhile knowledge about the world of appearances and how a science of this world could be developed, using Epicurean atomism as a hypothetical model.

Gassendi's mature theory about our knowledge of the world appears in his Syntagma Philosophicum, published in 1658 after his death. The work is enormous, containing 1,600 folio pages, printed in double columns. It is divided into three general sections, the first dealing with logic and theory of knowledge, the second with the natural world, and the third with ethics. Because of his skepticism, Gassendi did not regard metaphysics as a serious subject and so he omitted it entirely from his book.

At the outset, Gassendi seeks to establish a way to knowledge that is between the doubts of the skeptics and the complete assurances of the dogmatists. Neither the view that we can know nothing nor the view that we can know everything is tenable. The skeptics admit that we can know how nature appears to us. But they deny that we can know more than this. On the contrary, the dogmatists claim that we can know the real nature of things, which are not apparent to us. This, Gassendi contends, is exaggerating the power of the human mind. However, between skepticism and dogmatism there is a third possibility, which has been called constructive or mitigated skepticism, an acceptance of the thesis that although in a fundamental sense we cannot gain certain knowledge of the nature of reality, we can nevertheless gain a type of knowledge that we need have no reason to doubt and that will suffice to enable us to understand the world.

This limited knowledge is obtained first by accepting what is obvious to us, our sense experience, plus certain obvious conclusions from it, such as that things exist. Signs found in sense experience enable us to know about other matters not immediately obvious to the senses. The ancient Greek skeptics had admitted that, on the basis of the constant conjunctions found in experience, we could judge that certain things temporarily not apparent to us were the case, such as when we see smoke, we can judge that there is a fire. In addition, we are also able to judge, by means of our reasoning ability, that particular sense experiences indicate that the world has certain features, even though we are never able to perceive these features. Thus, we can judge from the appearance of sweat on the skin that it has pores.

Long before the invention of the telescope, Democritus was able to judge from the white color of the Milky Way that it is composed of an innumerable quantity of stars. This type of reasoning, which leads us to knowledge about the world, is based on a careful and cautious evaluation of our sense information by our reason, plus inferences, made from this information, based on careful reasoning and on certain general principles that we have learned from experience. The conclusions we reach in this way about the nature of the world are beyond doubt and are ultimately evaluated in terms of future information gained from experience (as in the case of the Milky Way) and from these conclusions in explaining the course of our experience. We do not discover the absolute truth in this way, but only a faint shadow of it. This faint shadow will turn out to be the most satisfactory scientific explanation that can be given of experience in terms of the hypothesis (confirmed by experience and reasoning) that the world is composed of atoms in motion.

In terms of this theory of knowledge Gassendi examines various logical systems, ancient and modern, to state the best method for attaining limited knowledge. Many of the classical devices, Gassendi finds, are practically useless. The philosophies of Francis Bacon and Descartes have serious defects, Gassendi claims. Our senses can err, and we cannot, no matter what we do, attain real knowledge of the inner nature of things. But a logical method that is based on sense information carefully analyzed on general, unquestionable principles gained from experience and careful reasoning, and constantly checked and verified, can serve as the instrument for attaining what truth is possible.


According to Gassendi what we can know about the world consists of a modified form of the atomism of Epicurus, modified in terms of the science of the time and the religious principles Gassendi maintained that he accepted. (Whether Gassendi was a sincere Christian has been, and still is, debated among scholars.) After surveying and criticizing the views of various philosophers about the nature of the world, Gassendi offers as the most probable theory (but not as the necessarily true one) the view that the actual components of the universe are indivisible atoms, moving in empty space. The supposed atoms are assumed to have been eternally created by God, to have different shapes, and to be moving at different rates of speed. Gassendi did not want mathematically describable atoms, since he feared this would lead to some sort of mathematical metaphysics. His atoms had features like those of ordinary experience. The atoms collided and presumably the result of all the collisions is the world that we perceive. A mechanical model related to our experience can then allow us to find empirical laws, make predictions, and explain relationships between different kinds of phenomena. In so relating the phenomenal world to the atomic world, there is no longer any need for Aristotelian purposes.

Appealing to the recent findings of scientists such as Evangelista Torricelli (16081647) and Blaise Pascal, Gassendi insists that the essential feature of atoms is solidity. In addition, they have the properties of extension, figure, and weight. They are conceived of as having the kinds of configurations found in ordinary experience, like those of wagon wheels and houses, rather than mathematically describable sizes and shapes. Gassendi had a distrust of those who maintained that nature was to be described in mathematical terms, since he felt that they were probably advocating some type of Platonic metaphysical theory about the nature of reality.

God has created the atoms and given them an impulse to move downward. They move at different rates of speed, and for this reason they collide with one another. The collisions change the courses of the atoms, causing still further collisions, and so on. The various changes that take place in the world, both on the apparent and on the nonapparent level, can be accounted for by the movements of the atoms, their collisions, and their combinations. Thus, the real world is conceived as a mechanism made up of small moving parts, the atoms. The qualities and movements of the atoms suffice to account for changes in the real world and the way in which the world appears to us. The qualities that we perceive, the colors, sounds, tastes, smells, and so on (the so-called secondary qualities), are not actually properties of real objects. Instead, they are the ways we perceive various atomic movements when they affect our sense organs.

Gassendi begins to modify his Epicurean theory when he discusses the cause of the movement of the atoms. He accepts the Scholastic thesis that the primary cause of motion is God. The evidence that God exists is the almost universal natural belief in a deity and the conclusion drawn from observing the order in the universe, namely, that there must be an orderer or designer of the world. That there are some atheists is dismissed by Gassendi as similar to the existence of blind people. That a few people lack the normal, natural human faculties and beliefs is no reason to doubt the reliability of the faculties and beliefs of the rest of humankind. Both the senses and our reasoning ability give us an adequate basis for accepting the view that there is a God.

One's conception of God is that of an omniscient and omnipotent being who is all-wise and all-good. He is the author and providential guide and cause of everything that exists and everything that happens in the world. Gassendi specifically rejects Epicurus's view that everything can be explained and accounted for solely in terms of the atoms and their motions. Where, he asks, do the atoms come from, and what makes them move? Furthermore, if the world were produced only by "the fortuitous concourse of atoms," why is it that the atoms never, by themselves, make a house, or a temple, or a book? Each of these seems to require a designer to organize the atoms in a specific way, and so does the universe in general.

Turning from physical events to mental ones, Gassendi attempts to give an atomic explanation of the nature of the soul. First, he exhibits his vast erudition by examining the opinions of many different ancient philosophers on the subject. Then he offers the theory that seemed most probable to him; namely, that the animal soul is a material object. Though we cannot see the soul, reason convinces us that it must exist. The various processes that occur in living beings, such as nutrition, sensation, and movement, could not take place were there not a soul. But what is the soul like? It is a tenuous material substance existing in the body. It is like a subtle fire, giving life to corporeal things somewhat as fire warms objects.

The human soul, however, is more complex than the animal soul, being composed of two parts. The first is the irrational soul, which is material and is like the soul of any other living thing. It accounts for the vegetative and sensitive processes that exist in man. This part of the human soul comes to us from our parents. Besides this, we possess another feature of our souls, the rational element that, Gassendi insists, contrary to Epicurus's view, is not corporeal and is not derived from other human beings, but only from God. The rational part of our souls, which is responsible for our higher intellectual activities, is also immortal. Epicurus had argued for the mortality of the soul, but Gassendi strongly insists that only the animal soul is mortal. As evidence for his belief in the immortality of the rational soul, Gassendi contends that the fact that it is immaterial suffices to show that it is immortal. Furthermore, the universal agreement of humankind on this point is offered as another proof, as well as the view that the divine and just government of the world would seem to require human immortality for a proper system of rewards and punishments to function.

Gassendi apparently believed that there was no conflict between his atomism and his views about man and God. Hence, Catholicism could be compatible with a strictly material account of the natural world. And although Gassendi was a heliocentrist he tried to present his astronomical views in such a way that they did not conflict with those of the church in its condemnation of Galileo Galilei.

Gassendi's atomism was as complete a scientific theory as any other offered in the first half of the seventeenth century. It rivaled Descartes's. However, as science developed later on, Gassendi's picture was replaced by that of Isaac Newton and others. No important discoveries are attributed to Gassendi's great scientific program.

Human Psychology

In his discussion of human psychology Gassendi presents a theory to explain how the various mental processes take place. This section culminates with an examination of the sources of all of our knowledge, which, to some extent, anticipates the views that appear in John Locke's An Essay concerning Human Understanding (1690).

The faculties of sensation and imagination are common to humans and animals. Gassendi even asserts that sensation occurs to some extent in plants and minerals. Sensation occurs by means of a physical process involving material particles affecting a sense organ and causing a sensation, which is a physical event in the brain. The faculty of the imagination, which includes the memory as well, operates on traces or remains of the physical sense impressions. These traces are conceived of as waves in the brain that are actuated by other motions in the body and then cause further movements in the brain, giving rise to sensations or feelings similar to the original sensation that caused the wave. Much of the account offered by Gassendi is close to that presented by his contemporary, the materialistic philosopher Thomas Hobbes.

The imagination has three functions: apprehension, judgment, and reasoning. We can apprehend, as a result of the wave motions, the exact experiences and sensations that have occurred. Because of movements inside and outside us, the various waves can be agitated at later times, so that we can now be aware of what we experienced yesterday. Also, different features of different experiences can be apprehended at the same time, giving rise to apprehensions of objects that have never, as such, been experienced. Thus, for example, our apprehension of a centaur results from our previous sense experience of a horse and a man, plus the simultaneous activation of part of the remaining wave that came from each of them. Judging and reasoning, which Gassendi insists takes place in both humans and beasts, involves comparing apprehensions and associating them together according to their relations in actual experience. The faculties of judgment and reasoning put various apprehensions into an ordered sequence based on the experienced sequences of sensations, plus the natural instinct that makes us expect certain consequences to follow from what we have experienced.

Up to this point the detailed psychological theory that Gassendi presents is much like that later developed by the British empiricists from Locke to John Stuart Mill. But Gassendi also insists that there is another mental faculty that exists in humans, but not in other animals, that of intelligence or understanding, which belongs to our rational souls. By means of intelligence we are able to know things that cannot be experienced in sensation, such as God, space, and time. By this faculty we are also able to know the abstract essences of things, which transcend the powers of the imagination. Thus, for example, the imagination can know what "man" is, in terms of the sensations received. But, the essence of man, what it is that makes him what he is, can be known only by the intelligence. Lastly, this highest mental faculty is capable of self-consciousness. It can reflect on its operations and those of the imagination and make us aware that we see, we think, and so on.

In terms of this theory of the nature of the soul Gassendi next offers his opinion about the origin of our ideas. He repudiates completely the theory of Descartes and of Herbert of Cherbury that we possess innate ideas. Instead, Gassendi insists on the principle accepted by Aristotle and Epicurus, that there is nothing in the understanding that was not first in the senses. At the outset, the mind is a tabula rasa, a blank tablet. All the particular ideas that the mind ever knows, such as that of the sun, either come directly from sense experience or result from combinations of elements furnished by the senses. General or abstract ideas are formed by the intelligence from the collection of sense materials. In this case the sense information is necessary, but not sufficient to account for general ideas, such as that of "man." The intelligence goes beyond the actual sense-data in forming a unique idea from all the particular sensations. With regard to ideas of incorporeal things, which cannot be known by the senses, sense experience and the imagination furnish the occasion for the understanding to gain this knowledge. Because of certain experiences the understanding thinks, reflects, abstracts, and arrives at ideas, such as that of God. The senses provide some of the basic materials for these ideas and provide the context in which the understanding reasons to reach a conception of an incorporeal being.

Thus, all ideas either come from the senses or result from intellectual activities that are either caused or occasioned by sense information. However, in the cases of abstract ideas and ideas of incorporeal things, the actual content does not derive from any particular sense experiences. General principles, such as "The whole is greater than the part," are formed by induction from various particular experiences. When all of our experiences exhibit the same characteristics, we reach a general conclusion, which then becomes the basis of all further reasoning.

Ethics and Religion

The last part of Syntagma deals with ethics. Gassendi's theory is only a slightly modified version of Epicurus's hedonism. Gassendi holds that every pleasure, considered in itself, is a good and that all things that are considered good have value only in terms of the pleasure they produce. A completely pleasurable life is one without pains and troubles. Ultimately, for Gassendi, such a life can be achieved only by God. We can mitigate the pains in our lives as much as possible and thus attain a relatively good life.

A major problem in interpreting Gassendi's contribution is that of assessing his intentions and actual beliefs. There has been great debate whether Gassendi was really a Christian. He has been seen both as the founder of modern materialism, a leading skeptic and libertine, and as a serious Christian trying to find a via media between his faith and the new science. There have been long debates, especially in French literature, about the so-called Le cas Gassendi. He was a close associate of some of the leading French freethinkers and took part in retreats with them where they boasted of being able to speak freely on all subjects. Gassendi was also a close friend of some leading church figures such as Mersenne. Gassendi and Mersenne shared similar views about science and its foundations. They agreed that science could not refute skepticism and each offered a form of mitigated skepticism as a way of carrying on useful science without metaphysics. Nobody ever questioned Mersenne's religious sincerity, and he remained in closest touch with Gassendi. No charges were ever made at the time about any heretical opinion or activity on the part of Gassendi.

Arguments about how to evaluate Gassendi still go on. Researches into his few theological writings go one direction, his materialism points another way, and his associations with leading figures of the time, ranging from Hobbes to Pascal, allow for many interpretations. Gassendi was a priest all his life and he was friendly with the most orthodox and the most unorthodox figures of his time. His philosophical system represented a cautious and careful attempt to explain the world in keeping with both the results of the new science and the official views of the Catholic Church. He may have seen, as few others of his time did, the importance of the values of his religious tradition, of the classical heritage, and of the new science, and at the same time fully appreciated what the skeptics had shown about man's fallible nature. Unlike Montaigne, Charron, and La Mothe Le Vayer (all of whom he admired), he did not wish to destroy the fruits of human efforts along with man's presumptuous and dubious claims. More like Sanches, he wanted to find a constructive resolution to the skeptical crisis of the Renaissance, but not in the form of the new dogmatisms of Herbert of Cherbury or Descartes. Living within a major religious tradition, he tried to show that by discarding Aristotelianism and by accepting the wisdom of the skeptics along with certain elements of Epicureanism, faith and the new scientific discoveries could coexist.

Gassendi adapted various features of the philosophy of Epicurus to the state of knowledge of his day, and he modified certain portions of Epicurus's theory that were not in keeping with the Christian religion. The result was a semiskeptical, semiempirical theory that portrayed the world in terms of an atomic structure. Gassendi's philosophy remained important throughout the seventeenth century and was the chief modern alternative to Descartes's. It began to lose its appeal and importance after the development of Newton's scientific theories. Many of the basic elements of later English philosophy appear in Gassendi's views, and he probably had great influence on such thinkers as Hobbes and Locke.

Influence and Significance

Gassendi was one of the foremost philosophers and scientists of the early seventeenth century. He was the most important rival and critic of Descartes, and he had a crucial role in the revival of the ideas of the ancient Greek skeptics and atomists. Gassendi began his intellectual career as a skeptic; a staunch follower of Sextus Empiricus and Montaigne. Gradually, he mitigated his skepticism in the face of the scientific revolution of the time, in which he played a major role, and he adopted more and more of a materialistic explanation of the world based on the ancient theory of Epicurus. Though a prominent Catholic priest of his day, Gassendi developed one of the first completely mechanistic and materialistic theories of modern times.

Gassendi's ideas had much influence in the seventeenth century. Although he published his work in huge Latin tomes, a French abridgement was made in the latter part of the century and many portions of his work appeared in English. His ideas were being taught in Jesuit schools in France, English universities, and even newly founded institutions in North America. Because of the close similarity between Gassendi's skeptical empiricism and some of the major portions of Locke's Essay concerning Human Understanding, there has been a good deal of discussion about whether Locke was influenced by Gassendi or used some of his works. It has been discovered that one of Gassendi's main works on Epicurus appeared in English in 1659 in Thomas Stanley's History of Philosophy, a work that Locke knew. Locke had also met a few of Gassendi's disciples in France, so it is possible that some influence occurred.

Gassendi's atomism never connected itself with basic scientific findings, so that modern atomism had to start elsewhere. There has been more interest in Gassendi in recent years. Many conferences were held for his 400th birthday in 1992, with explorations of many aspects of his thought and activities, and his scientific researches are proving important in the history of botany, geology, and other fields. There is growing interest in his critique of Cartesian philosophy and he is now being seen as a genuinely original thinker of the first rank.

See also Aristotelianism; Aristotle; Atomism; Bacon, Francis; Charron, Pierre; Common Consent Arguments for the Existence of God; Descartes, René; Epicureanism and the Epicurean School; Epicurus; Fludd, Robert; Galileo Galilei; Herbert of Cherbury; Hobbes, Thomas; La Mothe Le Vayer, François de; Locke, John; Materialism; Mersenne, Marin; Mill, John Stuart; Montaigne, Michel Eyquem de; Newton, Isaac; Pascal, Blaise; Patrizi, Francesco; Pyrrho; Ramus, Peter; Renaissance; Sanches, Francisco; Sextus Empiricus; Skepticism, History of.


works by gassendi

Exercitationes Paradoxica Adversus Aristoteleos (1624). Amsterdam: Apud Ludovicum Elzevirium, 1649.

Petri Gassendi Diniensis ecclesiae praepositi Opera Omnia. 6 vols. Lyon, France: Sumptibus Laurentii Anisson, & Ioan. Bapt. Deuenet, 1658.

Lettres familières à François Luillier pendant l'hiver, 16321633, edited by Bernard Rochot. Paris: J. Vrin, 1944.

Recherches métaphysiques. Translated and edited by Bernard Rochot. Paris: J. Vrin, 1962. Originally published as Disquisitio Metaphysica in 1644.

works about gassendi

Bernier, François. Abrégé de la philosophie de Gassendi. 7 vols. Paris: Fayard, 1992. French translation of some of Gassendi's major texts.

Bloch, Olivier R. La philosophie de Gassendi: Nominalisme, matérialisme, et métaphysique. The Hague: Martinus Nijhoff, 1971. Careful study of Gassendi's philosophical development.

Centre International de synthèse. Pierre Gassendi, 15921655, sa vie et son oeuvre. Paris: A. Michel, 1955. Lectures on Gassendi by Bernard Rochot, Alexandre Koyré, Georges Montgrédien, and Antoine Adam. Some excellent discussions of his philosophical and scientific views.

Gregory, Tullio. Scetticismo ed empirismo: Studio su Gassendi. Bari, Italy: Laterza, 1961. Important study emphasizing Gassendi's materialism and skepticism.

Hess, Gerhard. "Pierre Gassendi, Der Französische Späthumanismus und das Problem von Wissen und Glauben." Berliner Beiträge zur Romanischen Philologie 9 (1939): 199. Important study of Gassendi's views on faith and reason.

Joy, Lynn Sumida. Gassendi the Atomist: Advocate of History in an Age of Science. New York: Cambridge University Press, 1987. Study of Gassendi's humanistic development of his scientific theories.

Kroll, Richard W. F. The Material Word: Literate Culture in the Restoration and Early Eighteenth Century. Baltimore, MD: Johns Hopkins University Press, 1991. The impact of Gassendi's ideas in Restoration England.

Murr, Sylvia, ed. Gassendi et l'Europe. Paris: J. Vrin, 1997. Essays by many scholars on the 400th anniversary of Gassendi's birth.

Osler, Margaret. Divine Will and the Mechanical Philosophy: Gassendi and Descartes on Contingency and Necessity in the Created World. New York: Cambridge University Press, 1994. Contrasts Descartes's philosophical theology with that of Gassendi's.

Pintard, René. Le libertinage érudite dans la première moitié du XVIIe siècle. Geneva, Switzerland: Slatkine, 2000. New edition of Pintard's 1943 work. Gassendi is examined in relation to the libertins, and an irreligious interpretation of his views is offered.

Popkin, Richard H. The History of Scepticism: From Savonarola to Bayle. Rev. ed. New York: Oxford University Press, 2003. This is a newly revised and enlarged edition of Popkin's 1979 work, The History of Scepticism: From Erasmus to Spinoza. Depicts Gassendi's place in the history of skepticism.

Rochot, Bernard. "Le cas Gassendi." Revue d'histoire littéraire de la France 47 (1947): 289313. Defense of Gassendi's religious sincerity against the accusations of Pintard.

Rochot, Bernard. "Gassendi et le Syntagma Philosophicum." Revue de synthèse 47 (1950): 6779. Study of Gassendi's philosophy of science and scientific method.

Rochot, Bernard. Les travaux de Gassendi sur Epicure et sur l'atomisme, 16191658. Paris: J. Vrin, 1944. Important study of Gassendi's development. Contains a critical bibliography.

Turner, Anthony, and Nadine Gomez. Pierre Gassendi: Explorateur des sciences. Catalogue from the exhibit on Gassendi at the Musée de Digne, Digne-les-Bains, France, May 19October 18, 1992. Portrays the many scientific interests Gassendi had.

Richard Popkin (1967, 2005)

Gassendi (Gassend), Pierre

views updated May 18 2018

Gassendi (Gassend), Pierre

(b. Champte rcier, France, 22 January 1592; d, Paris, France; 24 October 1655)

Philosophy, astronomy, scholarship.

The Gassend family used the form Gassendi, according to the italianism then in style, but Pierre always signed himself Gassend. When a very young man, he was already a principal professor at Digne. His family had him continue his studies, which he pursued at Aix.

In 1614 he was accepted into minor orders and obtained a doctorate at Avignon. Two years later he took holy orders at Aix, where, from 1617 to 1623, he was charged with the teaching of philosophy. He was then initiated into astronomy by Gaultier de la Valette and into humanism by Peiresc, who became his patron.

A partisan of new ideas, Gassendi had printed in Grenoble a first volume of Exercitationes paradoxicae(1624) aimed against the Scholastics; he prudently withheld a second volume. His reputation—and the size of his correspondence—increased, and a cononary at Digne assured his independence (he became provost in 1634).

In Paris in 1624 and again in 1628, he met Mersenne, Mydorge, the du Puy brothers, and Luillier. In 1629-1630 he traveled with the latter in the Low Countries, where he met Isaac Beeckman.

On 7 November 1631 he observed the transit of Mercury, and in his Mercurius in sole visus (1632) he treated the event as a confirmation of Kepler’s ideas. He returned to Digne at the end of 1632 and undertook an extensive study of Epicurus’ thought, in the course of which he expressed his own. At some junctures he clearly departed from the ancient philosopher, but at others he placed statements inspired by materialism next to affirmations of orthodoxy with Which they were difficult to reconcile. He was, however, in no hurry to publish and seems even to have interrupted his researches in 1637 when Peiresc died. He resumed them again under the protection of the new governor of Aix-en-Provence, Louis de Valois, at whose behest he returned to Paris after election to the Assembly of the Clergy, a position he was obliged to renounce in 1641. At the request of Mersenne, he immediately thereafter composed the Cinquiémes objections to the Meditations of Descartes. The Instantiae was published in 1644.

Gassendi’s growing influence led Louis de Valois and Cardinal Alphonse de Richelieu, arch bishop of Lyons, to appoint him professor of mathematics (i.e., astronomy) at the Collège Royal in Paris in 1645. He published a Leçon inaugurale and a Cours, in which he set forth the system of Copernicus, while prudently falling back on that of Tycho. He taught for only a short time, however. His health was uncertain, and in 1648 Louis de Valois called him back to Provence, where he spent several years. His Animadversiones of 1649 contains a portion of his works on Epicurus together with the Greek text and translation of book 10 of Diogenes Laertius.

In Paris once again in 1653, Gassendi produced a third version of his great work entitled Syntagma Philosophicum, but he did not resume teaching. He died at the home of his host, Habert de Montmort, and was buried at St. Nicolas des Champs on 26 October 1655.

Gassendi’s Opera omnia was published in six volumes by his friends in Lyons (1658), according to a plan he had established himself. The first two volumes contain the syntagma; the third, a series of scientific works; the fourth, the astronomical lectures and observations; the fifth, the Liv́es of Astronomers and Epicurean works, as well as the Life of Peiresc; and the sixth, the Latin correspondence he had selected to preserve. The Animadversiones was not reprinted in its original form until 1675.

Although he excited the curiosity and attention of others, Gassendi did not seek to do so. He was not the leader of the “Libertines” and the future “philosophes.” Olivier Bloch, in his authoritative thesis, sees in Gassendi a belated humanist rather than an avantgarde thinker.1 There is no reason to question the sincerity of his testimonies of allegiance to a church of which he was a respected dignitary, as were his best friends, Peiresc and Mersenne. His true intellectual master was Galileo. In the Exercitationes of 1624 Gassendi had demonstrated his philosophic independence, and as early as 12 July 1625 he wrote to Galileo that he shared his Copernican ideas. But he never had to suffer the anxieties of the great Florentine. His choice of Epicurean atomism as a framework for the exposition of his ideas appears to have been more a revolt against Scholasticism than the expression of any profound conviction. Moreover, his erudition embraced all doctrines, including those of the church fathers, whereas he rejected such important elements of Epicureanism as the vertical fall and swerving of atoms.

Gassendi’s eclecticism was that of a skeptic assured that no one doctrine penetrates to the essence of things—indeed, this is a constant aspect of his thought. Yet he proceeded as would a historian for whom the human mind had exhausted all possibilities, in contrast to Descartes, who wrote as if unaware that anyone had ever done philosophy before him. Gassendi’s first published letter (to Pibrac, 8 April 1621) reveals an extreme diversity in what he chose to adopt and a great deal of personal assurance; he rejected only dogmatism, even when Epicurean. Bound by no fixed viewpoint, he could more easily go along with the traditions of his peasant milieu. If his morality preached happiness, his method for attaining it was conformist. A worldly type like Saint-Évremond thought him timid. A fanatic like J.-B. Morin consigned him to the flames. Descartes accused him of nothing less than materialism—thereby contributing more than slightly to the suspicion in which he was held. Gassendi, in turn, treated Descartes as a dogmatist. Moreover, he disappointed the materialists. Gassendi wished, Karl Marx declared, to put a nun’s habit on the body of Lais.2 In reality, Gassendi, believing Aristotle’s metaphysics to be pagan, attempted to establish a metaphysics that would be Christian, but in harmony with the fundamentally anti-Aristotelian contemporary science.

In this undertaking Gassendi may simply have become aware of his own ambiguities.3 A thorough study of the philosophical manuscripts preserved at Carpentras, Tours, and the Laurentian Library, and also of the published works; which repeat and correct each other (Disquisitio, 1644; Animadversiones, 1649; and the posthumous Syntagma, 1658), reveals neither the duplicity nor the denial suspected by Pintard4 but rather an effort to bring the Epicurean elements, accompanied by their materialist tendency, together with the traditional Christian elements. The two had previously been juxtaposed in Gassendi’s writings without being mingled—but not without contradiction. This became evident after the beginning of the dispute with Descartes in 1641 and in the new drafts of the Epicurean works first undertaken in 1642. The factors that Gassendi emphasized to achieve a synthesis between Epicureanism and Christianity were nominalism, finality, and vitalistic or chemical analogies. A discussion of these factors is required before asking whether Gassendi felt that Descartes’s reproaches really hit their target.

Nominalism had been born in a Christian atmosphere, where it remained a minority position, inspired by awareness of the limits of human understanding (modulus intellectionis). Feeble beings that they are, men (homonciones) cannot reach essential truth but only appearances, or phenomena, conditioned by laws that they did not make and cannot understand. God established these laws in order that things might endure and satisfy the needs of living creatures. Man establishes a system of signs, of names, which permits him to identify things perceived and to communicate with other men. But the concepts thus formed are conventions, not universal propositions. The universal does not exist ontologically. God has given man a mind capable only of conceiving the universal as the result of repeated contacts between the senses and well-ordered material realities. In animals imagination and memory record the facts to be retained. In man the rational spirit enables him to combine these representations with a view to action, guided by coherent predictions and based on reflections that take time and that are true inferences and not intuitions of some reality beyond the reach of sensation. But there is an evident providential finality in the Creation thus interpreted, and it is further illustrated by the wonders of the universe, of which man is the consummation and the goal. Hence, final causes are the “Royal Way,” They demonstrate the existence of God. The view was opposed to that of Descartes; and Gassendi, incidentally, refuted the ontological argument on which Descartes relied in much the same way that Kant later did.

Gassendi held that the atoms were the first things created, not in infinite number, as Democritus had said, but in a number sufficient to create the finite universe we know. They are endowed with an unalterable (in French inamissible) movement propelling them without interference in all directions through the void. There is no swerving (no clinamen). The collisions that necessarily take place annul motion and result in the appearance of immobility. Collisions form molecules which are particles identifiable by several attributes. The homogeneous atomic particles for their part are endowed only with shape, resistance, minimum size, and a “weight” that is the effect of their elementary movement. Molecules combine in fewer ways than atoms to form sensible, objects, possessing not powers, or internal qualities capable of activity, but mechanical forces. Various circumstances may liberate these forces in such a manner that impressions are made on other objects, notably the senses of living beings. At this level, other forces become effective—for example, chemical forces.5.

The dynamism that is sometimes noticed in Gassendian physics, and that justifies the expression semina rerum (borrowed from Lucretius) to designate the atoms, was merely this accumulation of an energy potential, conceivable even in biology. For living bodies are subjected to the same laws as others. Life is composed of movements of the “flower of matter,” the animal soul, which in a way resembles Descartes’s animal spirits and subtle matter. Science is thus relative to our needs; a view in which there was both sensationalism and pragmatism. Thus, Gassendi was not only a belated humanist but also a precursor of Locke, Condillac, and the positivists and empiricists of the eighteenth and nineteenth centuries.

These ideas contained the entire arsenal upon which future materialists could draw. Yet Gassendi had no thought of being a materialist in the later sense of d’Holbach or Marx. The clash with Descartes had revealed to him the way in which his works, still unpublished, could scandalize certain readers; his role as a priest led him to take this danger into account. But until then he had been able to conjoin faith with Epicureanism with as little fear as Galileo had earlier felt in juxtaposing Copernicus and the Bible.

Galileo had pointed out in his letter to the grand duchess of Florence (see below) that the Bible had originally been addressed to the early Jews in terms that they could understand, while Copernicus, for his part, had offered his work to the pope, and it was not at first thought heretical. By the same token, in Gassendi’s view, God had the power to make the world from atoms, as the Epicureans held, and was equally able to illuminate it by making the earth revolve around the sun on the Copernican hypothesis.

Galileo explained his theological position in relation to science in 1615 in his letter to the grand duchess of Florence. Christine of Lorraine. The argument was immediately and widely disseminated, and Gassendi undoubtedly saw it at Aix. It was published in Latin in Strasbourg as early as 1635.6 although in response to the condemnation of 1633. Descartes’s opposition also obliged Gassendi to take “precautions.” The word is Mersenne’s, who, by publishing the Cinquiémes objections had provoked the dispute with Descartes. He spoke of precautions in praising Gassendi’s works in a letter to Rivet (8 February 1642).7 That was precisely the date on which Gassendi undertook a new draft of his Epicurean works. Gassendi may probably have made these modifications in order to persevere in the same project, not to remove ambiguities or to modify it in some unexpected way. Mersenne gave his approbation to the earlier version, while expressing satisfaction with improvements in the new edition. Freethinkers were the only ones who judged differently and for their own reasons: they hoped that this physics would teach man to dispense with metaphysics.8.

Was such a result what Gassendi wished? Not at all. In the seventeenth century it was possible to conceive of God’s having created the universe in a single stroke, but after a model that permits the most convenient analysis. The “fable du monde,” which Descartes imagined to be separate from dogma without contradicting it, played a finalist role despite its author’s intentions. The atomic model could be employed in the same fashion. An admirer of Gassendi, the physician Deschamps, asked whether, without impiety, one could say that.9.

Gassendi’s influence on epistemology may now be stated more precisely. Koyré summarized it by saying that Gassendi contributed to the new science “the ontology that it needed,”10 In order to eliminate “powers” and “acts,” “accidents” and “qualities,” whether occult or not, it was necessary to suppose fixed and measurable data in a medium that in no way influences what is observed. Such are the atoms, endowed with shape, solidity, impenetrability, and a natural tendency to motion, which is weight. Such is the void in which bodies move without interference and without any change occurring in their nature through mere endurance. Time does not “eat away” at things; rather their mechanical and spatial relations change in the course of time. Contrary to the Scholastic view, space and time are neither substance nor accident. They exist when their content disappears and when nothing is happening. They establish the general frame of any knowledge of reality—with atoms redividing in a homogeneous void and moving in the unalterablecourse of time. Gassendi was one of the first to state this universal, categorial law of space and time.

Despite his influence on the ontology of classical physics, Gassendi’s scientific successes were not of the first rank. He owed what he achieved to his fidelity to the Democritean schema. Thus his study of Parhélies (1630) suggests a corpuscular explanation of light. His patient and thorough method made him a pioneer of observational astronomy, in which field Galileo had already set the example in 1610.11 But the observations, which almost fill the fourth volume of his Oeuvres, could serve only as a model for his contemporaries without leading him to any major discovery. For example, he corrected the geographical coordinates acknowledged for use in navigation in the Mediterranean, and he rejected the discovery of Jupiter’s new satellites announced by de Rheita in 1643.

The observation of the transit of Mercury, in which he alone was successful and which confirmed Kepler and, indirectly, Copernicus, caused widespread discussion. Koyré, however, reproaches him for having disregarded the mathematical form that enabled Kepler to determine the elliptical orbits of the Planets.12 Numerous sketches of various aspects of Saturn did not suggest to him the ring hypothesis, which Huygens proposed in 1659 without access to information that was much superior. Gassendi remained a prisoner of what the senses, even when fortified, are able to show. The Cours of 1644 at the Collége Royal (published in 1647) prudently presented Tycho Brahe together with Copernicus, while leaning sufficiently toward the latter to shock J.-B. Morin. In the De proportione qua gravia decidentia accelerantur of 1645, as in the De motu impresso, Gassendi defended—against the criticism of Le Cazre—the law of freely falling bodies, in which velocity is proportional to the square of the time elapsed and not to the distance traversed. But he never understood the importance of its having been deduced either from simple observations of motion on an inclined plane or in any other way.

In 1654 Gassendi joined to his other lives of astronomers the Life of Copernicus, in which the trial of Galileo, although not omitted, is barely mentioned. He thus insisted on the hypothetical and mathematical character of Copernicus’ work, whereas in 1647 the Institutio astronomica had explained the condemnation of Galileo by considerations relating to Galileo himself, but presenting no objections to Copernicus’ theories.13 It is further worth noting that Gassendi followed Galileo in the error of regarding the phenomen on of the tides as a proof of the motion of the earth. As was well known, the periodicity of the tides does not correspond to that of the diurnal movement, and Descartes did not make this mistake.14.

On one point—and it is an important one— Gassendi was more successful than Galileo: he correctly stated the principle of inertia. The experiment of the De motu impresso a motore translato, performed in 1640 in Marseilles, overthrew the argument of Copernicus’ opponents against the movement of the earth. Gassendi arranged to have a weight dropped from the top of a vertical mast on a moving ship in order to demonstrate that it fell at the foot of the mast and not behind it, thus sharing in its fall the forward motion of the ship. Galileo considered the experiment unnecessary; he foresaw the result by reasoning.15 Others, notably Bruno, had already spoken of it. But Gassendi understood that the composition of motions is a universal phenomenon: Every movement impressed on a body in motion in any direction whatsoever persists in Democritean space, which has neither up nor down. Motion is, in itself, a physical state, a measurable quantity, not— as the Scholastics maintained—the change from one state to another. It changes only through the interposition of another movement or of an obstacle.

Furthermore, Gassendi also corrected the formulation given by Kepler, for whom inertia was a tendency to rest: in classical physics, inertia is indifference to both motion and rest. On this point, Gassendi was guided by Galileo’s experiments on the pendulum, in which motion is maintained without any supplementary impetus. In addition, Kepler’s idea of magnetic effluents or forces gave him an, intimation of the existence of universal attraction or, rather, universal interaction—although he was no more successful than Descartes in conceiving its transmission otherwise than by contact.16.

Gassendian atoms and Cartesian subtle matter belong, as has been seen, to a single period of thought. Moreover, the idea of inertia was common to Beeckman, Gassendi, and Descartes, who all knew each other, and we know that Newton read Gassendi, as did Boyle and Barrow.

In 1650, on a mountain near Toulon, another experiment repeated the famous one of the Puy-de-Dôme.17 Gassendi fully appreciated the value of Pascal’s work. But the latter, in the Èquilibre des liquerṣ,,18 speaks indiscriminately of “weight and pressure of the air,” whereas, guided by the corpuscular picture and not by the hydrostatic scheme referred to in Pascal’s title, Gassendi could differentiate weight (which is constant for a given mass of air) from pressure (which varies according to the state of agitation, dilation, or contraction of this same mass). It is variations in pressure that affect the barometer and that measure not only the approximate height of the “column of air” but also the changes of state of the atmosphere, which are capable of influencing subsequent weather conditions. Of course, the barometric vacuum proves that the natural vacuum is not impossible; but what happens in the tube depends only an what happens outside. Koyré rightly points out that in this regard Gassendi anticipated Boyle, who read him closely and regretted not having done so earlier.19.

Gassendi applied his empirical and experimental sagacity to other fields, often in collaboration with Mersenne. Together they estimated the speed of sound as 1,038 feet per second, a passable approximation for the time.20 Physiology and dissection also interested Gassendi, as did all of natural history. However, he never completely renounced a false observation made at Aix in his youth when Payen made him “see” a communication between the two parts of the heart; but at least he esteemed Harvey and Pecquet. Numismatics and music also occupied him on occasion.

It is evident that Gassendi’s influence on science was more philosophical than technical and more critical than systematic. He rationalized physics, by introducing quantity into it through the measurements he undertook but above all by introducing atoms, those mutually combinable units that are capable of joining together in molecules and of producing measurable bodies. It is regrettable that with excessive modesty he reframed from propounding general views of the sort that can direct and enrich experiment a priori and that he did not envisage the possibility of applying mathematics to concrete, physical cases.21.


1. In Gassendi one sees primarily a precursor of Locke and Condillae, mentioned later in this article, as well as Hume, See Tricentenaire de Gassendi, pp.69, 227.

2. “Avant-propos” to “Mémoire sur Démocrite et Épicure.” in Oeuvres, J. Molitor. trans., I (Paris, 1946), xxii.

3. This and the following three paragraphs have been freely inspired by the excellent thesis of M. Bloch (see below), who generously lent it to the author.

4. Cf. Libertinoge érudit (Paris. 1943). p. 301, passim.

5. On this point, Bloch rehabilitates Etienne de Clave, a chemist condemned in 1624 by the Parlement of Paris.

6. Letter, in Le opere di Galileo Galilei. Favaro, ed. (Florence. 1890-1909), V, 309 ff. Gassendi does not approach the position of “double truth” to the extent that Bloch (see especially his ch. 11) thinks he does in his desire to reconcile Epicureanism and literal dogma. He thought he could juxtapose not two truths but facts equally real although differently expressed. Misunderstanding.” taught him what “precautions” (see following note) to take, precautions that Bloch sets forth with extreme precision; but these do not go as far as fideism.

7.Correspondence du P. Mersenne, XI, 38: “M. Gassendi réfute puissament, dans sa Philosophie Épicurienne, tout ce qui est contre le christianisme, et, comme vous avez fort bien remarqué, il y prend des précautions.” Rivet did not necessarily see what Mersenne was talking about. Mersenne, however, knew the drafts that preceded the one begun on this date as well as the drafts of the Instantiae, which was later joined to the Cinquièmes objections and Descartes’s Responsa to form the Disquisitio metaphysica (1644).

8. The author’s conclusions in this and the preceding paragraph are inspired by new material introduced by Gassendi in later editions that has been studied in depth by Bloth; the author’s opinions differ, in accordance with his knowledge of the respective positions of Descartes, Galileo, Gassendi, and mersenne in regard to each other.

9. Letter of 14 Aug. 1642, in Correspondence du P. Mersenne XI, 229-231.

10.Tricentenaire, pp. 176, 186.

11. Galileo sent Gassendi a telescope through Diodati; see letter of 25 July 1634 from Galileo to Diodati.

12.Tricentenarie, p. 188. n. 9. However, the Syntagma, I, 639a-b, mentions the elliptical trajectories of kepler.

13.Opera omnia (Lyons, 1658), V, 60b, end of book III, ch. 10.

14.Principes, IV, 49-52.

15.Dialogo, in Le operer di Galileo Galilel, VII 171; and Koyré Etudes galiléennes, pp. 215, 229, 249, 252; and in Tricentenaire, pp. 189 ff.

16. Despite everything that set them apart, Descartes and Gassendi were often bracketed by authors of the end of the seventeenth century. See also n. 5 and the corresponding text.

17. Gassendi had spoken of the Puy-de-Dôme experiment in a supp, to the Animadversiones (1649) and of his own in a letter (6 Aug. 1652) to Bernier, who had assisted him in that experiment. (Dating the letter “anno superiore,” he called Bernier’s memory into question: his own “diaire” testified that the experiment took place on 5 Feb. 1650.) All this is taken up again in the Syntagma (Opera omnia, I, 203-216). See Rochot’s articles in Aventure de l’esprit (Mélanges Koyré) and in Koyré, Tricentenaire, pp. 184 ff.

18. Pléiade ed., pp. 383 ff.

19.Tricentenaire, pp. 184 ff,; see also Bloch, ch., 8, especially n. 190, opposing Koyré.

20.Tricentenaire, p. 180.

21. Did Did Gassendi read the Saggiatore? See Le opere di Galileo Galilei, VI, 232, as well as the letter to Liceti (Jan, 1641), ibid., XVIII, 295: “The book of nature is written in mathematical language,”


I. Original Works. The contents of the six vols. of the Opera omina (Lyons, 1658), with a preface by Sorbiére, are summarily described in the text. The work has been reprinted twice: N. Averrani, ed. (Florence, 1727); and in facs. (Stuttgart, 1964), with a pref. by T. Gregory.

Following is a list of Gassendi’s principal individual works.

Scientific Works. Into this class fall Mercurius in sole visus et Venus invisa (Paris, 1632; 1658 ed., vol. IV); De apparente magnitudine solis humilis et sublimis epistolae quatuor (Paris, 1642; 1658 ed., vol, III); De motu impresso a motore translato epistolae duae (Paris, 1642; 1658 ed., vol. III), two letters to Dupuy, to which a third, to Gautier contra Morin and datged 1643, was added in the 1658 ed. (Gassendi’s friends had published the Gautier letter earlier [Lyons, 1649] without his knowledge); Oratio inauguralis habita in Regio Collegio, anno 1645, die Novembris XXIII, a P. Gassendo (Paris, 1645; 1658 ed., vol IV); De proportione qua gravia decidentia accelerantur (Paris, 1646; 1658 ed., vol. III); Institutio astronomica juxta hypotheseis tam veterum quam Copernici et Tychonis. Dictata a Petro Gassendo. Ejusdem oratio inauguaralis iterato edita (Paris, 1647; 1658 ed., vol. IV); and Tychonis Brahei . . . N. Coernici, G. peurbachi et J. Regiomontani . . . vitae (Paris, 1654; 1658 ed., vol V).

Philosophical Works. This second class includes Exercitationum paradoxicarum adversus Aristoteleos libri septem, in quibus praecipua totius Peripateticae doctrinae atque dialecticae excutiuntur; opinions vero aut nove, aut ex vetustioribus obsolete stabiliuntur, liber primus: In doctrinam Aristoteleorum universe, issued independently (Grenoble, 1624); bk. 2, In dialecticam Aristoteleorum, did not appear until the 1658 ed. (vol. III) with the shortened title Exerctitationes paradoxicae adversus Aristoteleos, in quibus . . . It was separately published shortly afterward as Exercitationum paradoxicarum liber alter in quo dialecticae Aristoteleae fundamenta excutiuntur (The Hague, 1659); a text and French trans. appeared as Dissertations en forme de paradoxes contre les aristotéliciens, B. Rochot, ed. and trans. (Paris, 1959), in which bk. 2. is corrected according to the MS at the Laurentian Library (this MS was formerly at Tours but was stolen from there by Libri).

Epistolica exercitatio, in qua praecipua principia philosophiae R. Fluddi, medici, reteguntur, et ad recentes illius libros adversus R. P. F. Marinum Mersennum scriptos respondetur (Paris, 1630; 1658 ed., vol. III).

The Disquisitio metaphysica seu dubitationes et instanitae adversus R. Cartesii metaphysicam, et responsa (Amsterdam, 1644; 1658 eds., vol. III) consists of the Objectiones quintae of 1641 with the publisher Sorbuère’s addition of the Instantiae of 1642, after Descartes’s Responsa. A text and French trans. of the Disquisitio was published as Recherche de la métaphysique, B. Rochot, ed. and trans. (Paris, 1962).

De vita et moribus Epicuri libri octo (Lyons, 1647; 1658 ed., vol. V).

Animadversiones in decimum librum Diogenis Laërtii, qui est de vita, moribus placitique Epicuri, 3 vols, (Lyons, 1649; 2nd ed., 2 vols., 1675), was reproduced only in part in the 1658 ed. The Greek-Latin text of Diogenes, with philological notes, does appear in vol. V. The reworked doctrinal commentary was incorporated into the Syntagma philosophicum (see below). The Philosophiae Epicuri syntagma, cum refutationibus dogmatum quae contra fidem christanam ab eo asseta sunt, oppositis per Perum Gassendum (1658 ed., vol. III), a sort of Epicurean breviary added as an appendix to to vol. II of the Animadversiones, appeared separately (The Hague, 1659) with the preface that Sorbièe had placed at the head of the 1658 ed.

His masterpiece, Syntagma philosophicum (logica, physica, ethica), was published posthumously (1658 ed., vols. I–II).

Correspondence. The Letters familières àFr. Luillier (hiver 1632-33), B. Rochot, ed. (Paris, 1944), is based on a MS that belonged to the heirs of the provost of Digne, now in the Bibliothèque Nationale (fonds latin 2643). The MS contains Gassendi’s drafts of the Latin letters in vol. VI of the 1658 ed. Most of the letters addressed to him in the same vol. are in the Bibliothèque Nationale. The French correspondence with Peiresc is in Lettres de Peiresc, Tamizey de Larroque, ed., IV (Paris, 1893). Gassendi is frequently mentioned in correspondence of the period; see especially Correspondence du. P. Mersenne, C. de Waard, Marie Tannery, and B. Rochot, eds. (Paris, 1932-). The bulk of his extensive correspondence in French and Latin is far from entirely known.

Miscellanleous Works. The biography De Nicolai Claudii Fabricii de Peiresc, senatoris aquisextiensis, vita (Paris, 1641; 1658 ed., vol. V) appeared in English as The Mirrour of True Nobility and Gentility, Being the Life of . . . N.C. Fabricius, Lord of Periesk, W. Rand, trans, (London, 1657). It is especially useful as a source for the historian of early seventeenth-century science.

A curious, and anonymous, pamphlet of 1654 designed to calm widespread fears occasioned by an eclipse of the sun is reasonably attributed to Gassendi. It was reprinted by B. Rochot, ed., in Bulletin de la Société d’tude du XVIIesiècle, no 27 (Apr. 1955), 161-177.

II.Secondary Liteature. The following items have been selected from the bibliography (343 items, including MSS, printed texts, biographical and doctrinal studies, and various articles) in the thesis of Olivier René Bloch, La philosophie de Gassendi: Nominalisme, matérialisme et méta physique (Paris, 1971); F. Bernier, Abrégé de la philosophie de Gassendi, 2nd ed., 7 vols, (Lyons, 1684); Henri Berr, Du scepticisme de Gassendi, B. Rochot, trans. (Paris, 1960), a trans, of the 1898 thesis An jure inter scepticos Gassendus numeratus fuerit; [J. Bougerel], Vie de Pierre Gassendi (Paris, 1737), which should be examined carefully because the author had access to documents that are now lost; G. S. Brett, Philosophy of Gassendi (London, 1908); G. Cogniot, “Pierre Gassendi, restaurateur de l’épicurisme,” in La pensée, no. 63 (Sept.-Oct. 1955); P. Damiron, Histoire de la phiosophie au XVIIesiècle (Paris-Neuchâtel, 1954), ch. VI, pp. 103-116; Tullio Gregory, Scietticismo ed empirismo, Studio su Gassendi (Bari, 1961); Pirre Humbert, L’oeuvre astronomique de Gassendi (Paris, 1936), completed by philosophes et savants (Paris, 1953), pp. 79-107; A Koyré, Études galiléennes (Paris, 1939), pp. 237 ff., repr. (Paris, 1966), pp. 304 ff,; F. A. Lange, Geschichte der Materialismus und Kritik senier Bedeutung in der Gegenwart, 2nd ed., 2 vols. (Iserlohn, 1837-1875), which appeared un French as Histoire du matérialisme, B. Pommerol, trans., 2 vols, (Paris, 1921), and in English as The History of Materialsm . . . , E. C. Thomas, trans., 3rd ed. (London, 1957), contains a section on Gassendi; Kurd Lasswitz, Geschichte der Atomistik vom Mittelalter bis Newton, 2 vols. (Hamburg-Leipzig, 1890; 2nd ed., 1928), II, 126-188; L. Mabilleau, Histoire de la philosophie atomistiue (Paris, 1895), pp. 400-422: P. Pendzig, Pierre Gassendis Metaphysik . . . (Bonn, 1908); René Pintard, Libertinage éudit, 2 vols. (Paris, 1943), which contains, in vol. I, numerous analyses in which Gassendi is portrayed as the leader of libertine tétrade and, in vol. II, an important bibliography (see also the MSS examined in his La Mothe le Vayer, Gassendi, Guy Patin (Paris, 1943]); B. Rochot, Les travaux de Gassendi sur Épicure et l’atomisme (Paris, 1944); G. sortais, La philosophie moderne depuis Bacon jusquà Leibniz, II (Paris, 1922); J. S. Spink, Free Thought From Gassendi to Voltaire (London, 1960); and P. F. Thomas, La philosophie de Gassendi (Paris, 1889), More a summary than an interpretation, it does not take into account the evolution of Gassendi’s thought as represented by the Syntagma. Two collections of studies are Pierre Gassendi, sa vie et son oeuvre, Centre International de Synthèse (Paris, 1955); and Tricentenaire de Gassendi, Actes du Congrès de Digne, 1955 (Paris-Digne, 1957).

The MSS enumerated by Bloch are in the Bibliothéque Nationale and in the libraries of Tours (706-710), Carpentras, and Florence (Laurentian). Biographical documents are at Aix-en-Provence, Digne, Grenoble, Marseilles, Munich, Oxford, Stuttgart, and Vienna; in the Archives du Ministère de la Guerre, Paris; and in the Bibliothèque Nationale (fonds français 12270 and fonds Dupuy.

Some texts have been translated into Polish by H. L. Kolakowski (Cracow, 1964) and into Russian by Sitkovsky (Moscow, 1966), with Studies.

It should be noted that the important study by G. Gusdorf, Révolution Galilèenne, vol III. of Les Sciences Humaines et la Pensée Occidentale, 2 vols. (Paris, 1969), was used in the preparation of this article.

Bernard Rochot.

Gassendi, Pierre

views updated May 29 2018


(b. Champtercier, France, 22 January 1592; d. Paris, France, 24 October 1655),

natural philosophy, atomism, astronomy, optics, mechanics. For the original article on Gassendi see DSB, vol. 5.

Since 1972, when Bernard Rochot wrote his entry for the DSB, Gassendi has been the object of increasing scholarly attention, and new light has been shed on virtually all aspects of his multifaceted philosophical and scientific activity. Besides adding some factual information to Rochot’s biographical account, the present postscript aims at providing a reassessment of four crucial issues, namely:

  1. the relation between Gassendi’s epistemological convictions and his scientific practice;
  2. the nonreductionist character of Gassendi’s matter theory, in which a crucial role is played by seminal virtues and organizing principles;
  3. Gassendi’s engagement in defense of Galileo Galilei’s theory of motion, of which he fully understood the cosmological implications;
  4. and, finally, Gassendi’s problematic attempts to derive the Galilean law of free fall from a physical explanation of gravity and to reconcile the principle of inertia with the laws governing the motion of atoms.

Early Intellectual Life . Second child of Antoine Gassend and Françoise Fabry, Pierre begun his schooling at Digne, and in 1602 was sent to Aix-en-Provence, where he studied philosophy under Father Philibert Fesaye and theology under Professor Raphaelis. In 1613, he was appointed principal of the College of Digne and professor of rhetoric. One year later he obtained the doctorate in theology at Avignon and was elected canon of the Cathedral of Digne. Ordained a priest in 1616, he became a professor of philosophy at Aix in 1617. In 1618 he started his astronomical observations under the guidance of Joseph Gaultier. The first entry in Gassendi’s astronomical diary records the observation of the comets made in Gaultier’s company in November 1618.

When, in 1621, the Jesuits took over teaching at Aix, Gassendi decided to return to Digne. His trips to Paris (1624, 1628, 1629, 1631) were marked by some important encounters: Marin Mersenne introduced him into his circle; the brothers Pierre and Jacques Dupuy, wardens of the king’s library, admitted him into their academy; with Elia Diodati, Gabriel Naudé and François de La Mothe Le Vayer he was to form the so-called Tétrade; with Ismael Bouillau he discussed astronomical matters; and with François Luiller he traveled through the Low Countries between 1628 and 1629.

However, the most important figure in Gassendi’s early intellectual life was certainly his first mentor, Nicolas Fabri de Peiresc, counselor to the Parliament of Provence and owner of an impressive library and of a collection of instruments. Peiresc offered Gassendi material and intellectual support, and the two shared an interest in humanism, philology, numismatics, cartography, astronomy, optics, and physiology.

Peiresc was always the first to be informed about the evolution of Gassendi’s Epicurean project. In 1626, Gassendi announced to Pieresc his intention to write an apology of Epicurus; and in 1631 he communicated his decision to extend his project beyond the field of ethics to include all of Epicurus’s philosophy (De vita et doctrina Epicuri). In the course of 1634, Gassendi sent to Peiresc eight manuscript quires (cahiers) containing the fruit of his work. These cahiers, which contained an apology De vita et moribus Epicuri(an updated version of which was published in 1647) and a preface De philosophia Epicuri universe, are now lost, but a manuscript containing a copy of the preface resurfaced at the British Library.

Several interests and engagements interfered with the elaboration of the Epicurean project. In 1629 Gassendi wrote an astronomical treatise, the Parhelia; in 1630 he published the Epistolica exercitatio, an attack against Robert Fludd written at Mersenne’s request; in 1631, he observed the transit of Mercury; in 1634, he composed the De veritate against Herbert de Cherbury and the first letter De apparente magnitudine solis humilis et sublimis(published in 1636).

Contrary to what has sometimes been maintained, the Exercitatio of 1630 was not intended as an attack against alchemy as such, but rather against the synthesis of alchemy, kabbalah, and religion operated by Fludd. In the Exercitatio a distinction is drawn between “false alchemy” and “real alchemy.” While rejecting Fludd’s interpretation of Genesis in alchemical terms, and his identification of God with the Platonic world soul, Gassendi recognized the importance of alchemy for natural philosophy, and even expressed the conviction that the transmutation of metals would become possible, if the seeds of gold were discovered. In the Exercitatio one also finds the hypothesis, which reappears in the Syntagma, that the generation and transformation of metals resemble biological processes, as they are brought about by seminal powers.

Both the Exercitatio against Fludd and De veritate against Herbert de Cherbury echo the epistemological stance already taken in Gassendi’s Exercitationes of 1624. In all these works Gassendi chastises the ambition of arriving at universal truths by means of a purely intellectual act (be this the intellectus principiorum of the scholastics or the instinctus naturalis of Herbert de Cherbury) and opposes to the dogmatic ideal of a scientia per causas his own model of a philosophia aperta et sensibilis, based on a direct reading of the book of nature. When, in March 1634, Gassendi left Digne for an extended sojourn at Peiresc’s villa at Aix-en-Provence, the two men engaged in an intense scientific activity that perfectly conformed to Gassendi’s ideal of a descriptive-cumulative science. Between 1634 and 1636, they undertook studies of meteorological phenomena as well as geological investigations concerning the nature of stones, minerals and fossils, the formation of caverns, and the circulation of waters; they planned to produce a lunar atlas, for which Claude Mellan began to make the engravings; most importantly, Gassendi followed Peiresc in his numerous microscopic observations and in his study of the physiology of vision.

Peiresc had acquired a Drebbel microscope as early as 1623, and he used the instrument to test recent anatomical and physiological discoveries, including William Harvey’s discovery of the circulation of blood and Gaspare Aselli’s discovery of the lactic vessels. Interestingly the two findings appeared to be incompatible with one another, for Aselli believed, in accordance to Galen’s view, that these vessels transported intestinal lymphatic material to the liver, the organ in which blood was produced. Gassendi himself found it difficult to dismiss Galen’s authority. While in 1629 he thought that Harvey’s theory of the continuous circulation of blood was probable and well-founded, in the Syntagma he would eventually endorse some of Jean Riolan’s and Guy Patin’s objections. The anatomical observations conducted with Peiresc were to be invoked in the Disquisitio metaphysica and in the Syntagma as a proof of the existence of final causes in the biological realm. Peiresc and Gassendi also anatomized the eyes of many different animals, seeking a physiological, rather than psychological, explanation of the problem of retinal inversion. After being inverted by the convex crystalline, the image was reinverted by the concave retina and reflected back into the vitreous humor.

The Microscope and the Atoms . If Peiresc’s enthusiasm for the microscope had been essentially directed toward its descriptive capacity, Gassendi appreciated it mostly for its analytic potential, viewing it as an ally in the rehabilitation of atomism. Waiting for the day that microscopes would become so powerful as to make atoms visible, Gassendi used the available instruments to collect empirical evidence in favor of his theory of matter. This evidence was, however, somewhat ambivalent. If applied to little organisms, the microscope revealed an immense variety of different forms underneath a seemingly homogeneous surface: the fact that an insect no bigger than a dot, when put under a magnifying lens, displayed a great variety of organs, appeared as an illustration that innumerable atomic shapes could combine to form compound bodies. The microscopic observation of salts and minerals suggested instead that nature repeated its basic patterns from the macroscopic world down to the atom. In 1636, after a visit to saline springs, Gassendi wrote to Peiresc that the microscopic observation of salts seemed to validate the principles of Epicurean philosophy: the fact that these cubic, hexahedral, or octahedral solids were made out of components of the same shape allowed for the conclusion that this shape was preserved up to the level of atoms. His observation of salts, moreover, further strengthened Gassendi’s belief in the existence of seminal virtues in charge of organizing the corpuscles according to pre-established patterns.

Since his visit to the chemist Jan Baptista van Helmont, in 1629, Gassendi had begun to embed ideas of Paracelsian extraction within his Epicurean program, a task rendered easier by Lucretius’s use of the expression “seeds of things” (semina rerum) to designate atoms. Of particular influence on Gassendi’s treatment of so-called natural res mixtae (animals, plants, and fossils) was the Paracelsian synthesis provided in Petrus Severinus’s Idea medicinae (1571). In the Syntagma, Gassendi explains that growth and internal organization of all beings, from metals and crystals upward, are due to seminal forces which are not immaterial principles, but rather physical agents composed of very active corpuscles endowed by God with a program. But how exactly the “divine and incomparable Architect” has set up the “occult internal economy” that leads to the formation of the seeds responsible for the generation of living forms remains unknown, as Gassendi professes in his Syntagma.

However, he explicitly adopts Severinus’s term mechanical spirits to account for this process. There is, from the historians’ point of view, some irony in this seemingly oxymoronic expression. It has often and convincingly been argued that Gassendi’s atomism was not of a mechanical sort, if by “mechanical” we understand the Cartesian program of reducing all upper-level phenomena to the structure of, or collisions by, material corpuscles. But before Robert Boyle popularized the term mechanical philosophy, this predicate had a wide variety of meanings. In fact, when invoking Severinus’s “mechanical spirits,” Gassendi meant intelligent agents, which had nothing in common with René Descartes’s inert chunks of matter.

Astronomical Observations and Optical Puzzles . A further influence on Gassendi’s matter theory was astronomy and in particular the observations he carried out in the 1630s. In his Admonitio of 1629, Johannes Kepler had predicted a solar transit of Mercury for 7 November 1631, explaining how the shadow of the planet on the solar disk could be used to calculate its apparent size. Gassendi, who was in Paris at the time, was the only person to observe the phenomenon predicted by Kepler. Using a telescope, he

projected the image of the sun on a paper screen, and on 7 November he saw a tiny shadow appear on the solar disk. As he explained in the Mercurius in Sole visus, the smallness of the apparent size of Mercury seemed to indicate that the solar system was much bigger than so far believed. The observation of the transit of Mercury triggered Gassendi’s interest in optical questions. Between 1636 and 1641 he performed various experiments to measure the shadows cast by a larger or smaller apparent sun. In his letters De apparente magnitudine solis humilis et sublimis, Gassendi invoked the corpuscular composition of light rays and atmosphere to account for some curious optical phenomena. He explained that when the sun is at the horizon more light rays are absorbed by the atmosphere than when it is at the zenith, so that less luminosity reaches the eye. This provokes a dilation of the pupil, which makes the sun appear larger. The optical experiments further reinforced Gassendi’s conviction that natural philosophy cannot rely exclusively on mathematical reasoning, which is often misleading: that the midday sun produces the smallest shadows contradicts the principles of geometrical optics, which would require that the shadow cast by the greater apparent sun (i.e., the horizon sun) be smaller than the one cast by the smaller apparent sun (i.e., the sun at the zenith).

Atoms, Mechanics, and Cosmology . When Peiresc died, on 24 June 1637, Gassendi was so devastated that he interrupted his scholarly activity as well as his epistolary contacts for nearly two years. In 1638, however, he encountered the new governor of Provence, Louis de Valois, who was to become his new protector. The two men entertained a very dense correspondence. Besides keeping de Valois informed about the advancement of his research, Gassendi devised for him a philosophy course, articulated in fifty-nine letters written between October 1641 and November 1642. The course followed the contents and the structure of the De vita et doctrina Epicuri. Gassendi started with an apology for Epicurus, continued with a historical analysis of various philosophical traditions, then offered a history of dialectics, and finally engaged in a reconstruction of Epicurus’s thought, notably of his canonics and physics. The letters reveal how different Gassendi’s relation with de Valois was from that with Peiresc. He treated the new mentor with the respect due to a prince and the benevolence due to an eager, but not particularly talented student.

In October 1640, de Valois witnessed a spectacular event of which he was also the sponsor: Gassendi left the port of Marseille on a galley to perform an experiment imagined by Galileo in the Dialogo. Gassendi verified that a ball dropped from the top of the mast landed at its foot no matter whether the ship was at rest or sailing at high speed. The experiment had important cosmological implications, for it falsified one of the crucial arguments against the daily motion of Earth. In the year of Galileo’s death, 1642, Gassendi published the Epistolae duae de motu impresso a motore translato, in which he provided a physicomathematical analysis of this experiment, as well as an examination of its cosmological implications. One of the major conceptual novelties introduced there was the identification of gravity with the attractive force of Earth. According to Alexandre Koyré’s interpretation, which many scholars have endorsed, the recognition of the external nature of gravity allowed Gassendi to publish the first correct statement of the principle of rectilinear inertia. This judgment is, however, overly generous. True, in the Epistolae and in the Syntagma, Gassendi does state that in an imaginary void space a stone set in motion would persist in a state of uniform rectilinear motion. But when talking about the behavior of bodies in the real world, he does not hesitate to describe uniform circular motion (e.g., of planets, or of a ball rolling on Earth’s surface) as maximally natural. Also, contrary to Galileo, he does not have the slightest notion of a centrifugal force. Moreover, as Koyré himself recognized, the principle of inertia is incompatible with Gassendi’s laws of microscopic dynamics. Far from being indifferent to motion and rest, Gassendi’s atoms are endowed with an innate tendency to move at maximum speed, so that the variety of motions of macroscopic bodies must be explained as the result of the clashes among the underlying atoms. Rather than in the formulation of some principle of inertia, the importance of Gassendi’s Epistolae resides in the emphasis that Gassendi places on the relation between Galileo’s new science of motion and Copernican cosmology.

Gassendi’s attempt to derive Galileo’s law of natural acceleration from a causal analysis of free fall is also interesting, although ultimately unsuccessful. Contrary to Descartes, who considered Galileo’s theory of motion a mathematical abstraction, incompatible with any mechanistic explanation of gravity, Gassendi stubbornly tried to devise a causal account of free fall that could be reconciled with the odd-number law. In the Epistolae de motu he described falling bodies as being subjected to the joint action of two forces. The first, which he calls the vis attrahens, is the force of the earth, which emits chains of magnetic particles capable of reaching distant bodies and carrying them back. The second, which he calls vis impellens, is the force of the air, which rushes upward to fill the space evacuated by the falling body and thereby produces an additional pressure from behind.

In the course of his polemics with the Jesuit Pierre Le Cazre, which led to the publication of the Epistolae de proportione qua gravia decidentia accelerantur(1646), Gassendi came to the conclusion that the vis attrahens was by itself capable of bringing about an acceleration according to Galileo’s odd-number law. But the relation Gassendi establishes between causal explanation and mathematical analysis of fall appears forced and artificial. For in no way can he account for the fact that a force acting through contact, by means of discrete pushes, will bring about a continuous acceleration. In the Syntagma Gassendi reconfirms his support for Galileo’s theory of motion, without, however, subscribing to its mathematical foundation. He denies that physical magnitudes can be made out of mathematical points, and postulates the composition of space and time out of extended minima.

In the Epistolae and the Syntagma, Gassendi stressed the conjectural character of his explanation of gravity. He claimed to be certain about the general mode of action of vis attrahens, which can operate only through contact, but admitted his ignorance concerning the particular configuration of the magnetic chains. Yet, the conjectural science proposed here was no longer the scientia experimentalis described in the Exercitationes, which denied to the human mind any access to the causes of things. In the Disquisitio metaphysica of 1641, Gassendi endorsed a conception of the scope of science that perfectly conformed to his new scientific practice. He declared science to be something more than a simple collection of sensible data and admitted the legitimacy of a process of inference that enabled the mind to proceed from known effects to possible causes.

In the Epistolae de motu, Gassendi even dared to expound Galileo’s proof of Earth’s motion based on the tidal phenomenon. Although he presented it as a faithful summary of someone else’s theory, he surreptitiously modified it so as to render it more compatible with the observed phenomena. Interestingly enough, a revised version of Galileo’s tidal theory is also found in the Syntagma, although Gassendi there officially adheres to Tycho Brahe’s cosmological system. To be sure, this adhesion represents a last-minute act of obedience to the Catholic Church. If one looks at the various drafts of the work, one sees that in 1642 (Ms. Tours 709) Gassendi presented Ptolemy’s and Copernicus’s as the only two possible world systems, and that in 1643 (Ms. Tours 710) he summarized Tycho’s proposal in merely ten lines. From the published version of the Syntagma, where attention is given to the Ptolemaic, Tychonic, and Copernican systems, it is still evident that Gassendi’s preference is for the latter, which is described as the most simple and elegant. But in two passages that were added to the manuscript at a late stage, the Tychonic cosmos is declared to be the only one capable of saving the phenomena while being compatible with sacred scriptures.

If in matters of cosmology Gassendi was ready to advocate the compromise favored by the church, he fought until the end of his life to demonstrate the compatibility between atomism and the Catholic faith. In a moment in which Jesuit natural philosophers were obliged to subscribe to the traditional Peripatetic theory of substance and accident as the only one that could explain the real presence of Christ in the Eucharist, Gassendi did not hesitate to get rid of substantial and accidental forms. To the Jesuit Le Cazre, who reminded him of the dangers that atomism posed to religion, Gassendi answered that tran-substantiation was a “supernatural process” that should and could not be explained in physical terms.

With extraordinary erudition and seemingly orthodox piety, Gassendi argued that Epicurus was, just like Aristotle, a pagan philosopher in need of mending. Epicurus had to be corrected in some crucial points, notably with respect to

  1. the creation and dissolution of the world and on the eternity of atoms;
  2. the infinite plurality of worlds;
  3. the blindness of causal necessity;
  4. the use of parts in living organisms; and
  5. the material and atomistic constitution of the soul.

But the fruits that could be obtained from a converted Epicurus were immensely more palatable than those gained from the Christianized Aristotle.



The Selected Works of Pierre Gassendi. Edited and translated by Craig Brush. Texts in Early Modern Philosophy. New York: Johnson Reprints, 1972.

Institutio Logica (1658). A Critical Edition with Translation and Introduction. Edited and translated by Howard Jones. Assen, Netherlands: Van Gorcum, 1981.

Descartes and His Contemporaries: Meditations, Objections, and Replies. Edited and translated by Marjorie Grene and Roger Ariew. Chicago: University of Chicago Press, 1995.

Pierre Gassendi (1592–1655): Lettres Latines. Edited and translated into French by Sylvie Taussig. Turnhout, Belgium: Brepols, 2004.


Alberti, Antonina. Sensazione e realtà. Epicuro e Gassendi. Florence, Italy: Olschki, 1988.

Ariotti, Pietro. “From the Top to the Foot of a Mast on a Moving Ship.” Annals of Science 28 (1972): 191–203.

Beaulieu, Armand. “L’enigmatique Gassendi: Prevot et savant.” La vie des sciences 9 (1992): 205–229.

Bernier et les gassendistes. Special issue of Corpus, edited by Sylvia Murr, 20–21 (1992): 47–64.

Brundell, Barry. Pierre Gassendi: From Aristotelianism to a New Natural Philosophy. Dordrecht, Netherlands: Reidel, 1987. The book describes Gassendi’s commitment to empiricism, Copernicanism, and Epicurean physics as being subordinated to the overall project of overthrowing Aristotle’s metaphysics and natural philosophy.

Clark, Joseph T. “Pierre Gassendi and the Physics of Galileo.” Isis 54 (1963): 352–370.

Clericuzio, Antonio. Elements, Principles and Corpuscles. A Study of Atomism and Chemistry in the Seventeenth Century. Dordrecht, Netherlands: Kluwer, 2000. The chapter on Pierre Gassendi (pp. 63–74) investigates the connection of atomism and chemistry in Gassendi’s thought.

Debus, Alan G. “Pierre Gassendi and His Scientific Expedition of 1640.” Archives internationales d’histoire des sciences 63 (1963): 133–134.

Descartes versus Gassendi. Special issue of Perspectives on Science, edited by Roger Ariew, 3 (1995): 425–581.

Detel, Wolfgang. “War Gassendi ein Empirist?” Studia leibnitiana 6 (1974): 178–221.

——. Scientia Rerum Natura Occultarum: Methodologische Studien zur Physik Pierre Gassendis. Berlin: De Gruyter, 1978.

——. “Scepticism and Scientific Method: The Case of Gassendi.” In Wissensideale und Wissenskulturen in der frühen Neuzeit; Ideals and Cultures of Knowledge in Early Modern Europe, edited by Wolfgang Detel and Claus Zittel. Berlin: Akademie Verlag, 2002.

Dumont, Simone, Jean Meeus, and Marcel Anstett. “Passage de Mercure devant le Soleil, observé par Gassendi (1592–1655), le 7 novembre 1631.” L’Astronomie 106, no. 4 (1992): 5–7.

Festa, Egidio. “Gassendi interprete di Cavalieri.” Giornale critico della filosofia italiana 71 (1992): 289–300.

Fisher, Saul. Pierre Gassendi’s Philosophy and Science. Leiden, Netherlands: Brill, 2005.

Galluzzi, Paolo. “Gassendi and l’Affaire Galilée of the Laws of Motion.” In Galileo in Context, edited by Jürgen Renn. Cambridge, U.K.: Cambridge University Press, 2001.

Gregory, Tullio. “Pierre Gassendi dans le quatrième centenarie de sa naissance.” Archives Internationales d’Histoire des Sciences 42 (1992): 203–226.

Hirai, Hiro. Le concept de semence dans les théories de la matière à la Renaissance. De Marsile Ficin à Pierre Gassendi. Turnhout, Belgium: Brepols, 2005. The concluding chapter (pp. 463–491) traces notably Gassendi’s debt to Petrus Severinus for the notion of seminal forces.

Jones, Howard. Pierre Gassendi (1592–1655): An Intellectual Biography. Nieuwkoop, Netherlands: B. de Graaf, 1981.

Joy, Lynn Sumida. Gassendi the Atomist: Advocate of History in an Age of Science. Cambridge, U.K.: Cambridge University Press, 1987. Joy argues that Gassendi’s atomistic natural philosophy was influenced and shaped by his historical researches. Lennon, Thomas L. The Battle of Gods and Giants: The Legacies of Descartes and Gassendi, 1655–1715. Princeton, NJ: Princeton University Press, 1993.

Lüthy, Christoph. Matter and Microscopes in the Seventeenth Century. PhD thesis, Harvard University, 1995. Describes (pp. 255–291) Gassendi’s microscopic research and its impact on his atomism.

Lüthy, Christoph, John E. Murdoch, and William R. Newman, eds. Late Medieval and Early Modern Corpuscular Matter Theories. Leiden, Netherlands: Brill, 2001. Contains the following chapters on Gassendi: Clericuzio, Antonio. “Gassendi, Charleton and Boyle on Matter and Motion,” pp. 467–482; Osler, Margaret. “How Mechanical Was the Mechanical Philosophy? Non-Epicurean Aspects of Gassendi’s Philosophy of Nature,” pp. 423–439; Palmerino, Carla Rita. “Galileo’s and Gassendi’s Solutions to the Rota Aristotelis Paradox: A Bridge between Matter and Motion Theories,” pp. 381–422.

Mazauric, Simone. Gassendi, Pascal, et la querelle du vide. Paris: Presses universitaires de France, 1998.

Messeri, Marco. Causa e Spiegazione: la Fisica di Pierre Gassendi. Milan, Italy: F. Angeli, 1985. Follows the parallel evolution of Gassendi’s epistemology and natural philosophy, through an analysis of his concepts of causality and explanation.

Murr, Sylvia, ed. Gassendi et L’Europe (1592–1792). Actes du colloque international de Paris, “Gassendi et sa postérité (1592–1792),” Sorbonne, 6–10 Octobre 1992. Paris: J. Vrin, 1997.

Osler, Margaret J. Divine Will and the Mechanical Philosophy: Gassendi and Descartes on Contingency and Necessity in the Created World. Cambridge, U.K.: Cambridge University Press, 1994. Osler argues that Gassendi’s probabilistic epistemology and his empiricist approach to science were deeply influenced by his voluntaristic theology.

Palmerino, Carla Rita. “Pierre Gassendi’s De philosophia Epicuri universe Rediscovered. New Perspectives on the Genesis of the Syntagma philosophicum.” Nuncius 14 (1999): 131–162.

——. “Gassendi’s Reinterpretation of the Galilean Theory of Tides.” Perspectives on Science 12 (2004): 212–237.

——. “Galileo’s Theories of Free Fall and Projectile Motion as Interpreted by Pierre Gassendi.” In The Reception of the Galilean Science of Motion in Seventeenth-Century Europe, edited by C. R. Palmerino and J. M. M. H. Thijssen, 137–164. Boston Studies in the Philosophy of Science, 239. Dordrecht, Netherlands: Kluwer, 2004.

Pancheri, Lillian U. “The Magnet, the Oyster, and the Ape, or Pierre Gassendi and the Principle of Plenitude.” Modern Schoolman 53 (1976): 141–150.

Pav, Peter Anton. “Gassendi’s Statement of the Principle of Inertia.” Isis 57 (1966): 24–34.

Popkin, Richard. The History of Scepticism: From Savonarola to Bayle. Rev. ed. Oxford: Oxford University Press, 2003.

Sarasohn, Lisa T. “Motion and Morality: Pierre Gassendi, Thomas Hobbes, and the Mechanical World View.” Journal of the History of Ideas 46 (1985): 363–379.

——. “French Reaction to the Condemnation of Galileo, 1632–1642.” Catholic Historical Review 74 (1988): 34–54.

——. Gassendi’s Ethics: Freedom in a Mechanistic Universe. Ithaca, NY: Cornell University Press, 1996. Examines how Gassendi made Epicurean ethics consonant with the new science and with the Christian notions of provindence and free will.

Société Scientifique et Littéraire des Alpes de Haute-Provence, ed. Quadricentenaire de la naissance de Pierre Gassendi, 1592–1992. Actes du Colloque International, Digne-les-Bains, 18–21 Mai 1992. 2 vols. Digne-les-Bains, France, 1994.

Taussig, Sylvie. Pierre Gassendi (1592–1655). Introduction à la vie savante. Turnhout, Belgium: Brepols, 2003.

Turner, Anthony, and Nadine Gomez, eds. Pierre Gassendi, explorateur des sciences. Catalogue de l’exposition, quatrième centenaire de la naissance de Pierre Gassendi. Digne-les-Bains, France: Musée de Digne, 1992.

van Helden, Albert. “Saturn and His Anses.” Journal for the History of Astronomy 5 (1974): 105–121.

——. “The Importance of the Transit of Mercury of 1631.” Journal for the History of Astronomy 7 (1976): 1–10.

Carla Rita Palmerino

Gassendi, Pierre (1592–1655)

views updated Jun 11 2018


GASSENDI, PIERRE (15921655), French Catholic priest and philosopher. Born in Provence on 22 January 1592, Gassendi was admitted to the clerical state in 1604 and received his doctor of theology degree at the University of Avignon in 1614. He studied philosophy and theology at the college of Aix-en-Provence, where he later taught from 1616 to 1622. He published his first book, Exercitationes Paradoxicae adversus Aristoteleos, in 1624, a work in which he criticized Aristotelianism by using the skeptical arguments of the ancient philosopher Sextus Empiricus (fl. c. 200 C.E.). Having rejected Aristotelianism, Gassendi undertook the task of creating a new, complete philosophy, one that included the three traditional areas: logic, physics, and ethics. Writing in the style of the Renaissance humanists, Gassendi chose the ancient atomist and hedonist Epicurus (341271 b.c.e.) as his model. Before European intellectuals could accept the philosophy of Epicurus, it had to be purged of various heterodox notions, such as materialism and the denial of creation and providence.

Gassendi worked on his Epicurean project from the 1620s until his death. The massive, posthumous Syntagma Philosophicum (1658) is the culmination of this project. It consists of three parts: "The Logic," "The Physics," and "The Ethics." In "The Logic," Gassendi presented his theory of knowledge, which he had first articulated in the Exercitationes. His empiricist theory of knowledge was an outgrowth of his response to skepticism. Accepting the skeptical critique of sensory knowledge, he denied that we can have certain knowledge of the real essences of things. Rather than falling into skeptical despair, however, he argued that we can acquire knowledge of the way things appear to us. This "science of appearances" is based on sensory experience and can only attain probability. It can, nonetheless, provide knowledge useful for living in the world. Gassendi denied the existence of essences in either the Platonic or Aristotelian sense and identified himself as a nominalist.

In "The Physics," Gassendi presented a Christianized version of Epicurean atomism. Like Epicurus, he claimed that the physical world consists of indivisible atoms moving in void space. Unlike the ancient atomist, Gassendi argued that there exists only a finite, though very large, number of atoms, that God created these atoms, and that the resulting world is ruled by divine providence rather than blind chance. Deeply involved in the natural philosophy of his time, Gassendi tried to provide atomistic explanations of all the phenomena in the world, including the qualities of things, inanimate bodies, plants, and animals. In contrast to Epicurus's materialism, Gassendi enriched his atomism by arguing for the existence of an immaterial, immortal soul. He also believed in the existence of angels and demons. His theology was voluntarist, emphasizing God's freedom to impose his will on the creation.

Adopting the hedonistic ethics of Epicurus, which sought to maximize pleasure and minimize pain, Gassendi reinterpreted the concept of pleasure in a distinctly Christian way. He believed that God endowed humans with free will and an innate desire for pleasure. Thus, by utilizing the calculus of pleasure and pain and by exercising their ability to make free choices, they participate in God's providential plans for the creation. The greatest pleasure humans can attain is the beatific vision of God after death. Based on his hedonistic ethics, Gassendi's political philosophy was a theory of the social contract, a view that influenced the writings of Hobbes and Locke. His emphasis on free willboth human and divineled him to reject astrology, which he considered absurd, and other forms of divination that entailed any kind of hard determinism in the world.

Gassendi was an active participant in the philosophical and natural philosophical communities of his day. He corresponded with Galileo during his troubles with the church, and interacted with both Hobbes and Descartes. He conducted experiments on various topics in natural philosophy, wrote extensively about astronomy, corresponded with important natural philosophers, and wrote a treatise defending Galileo's new science of motion. Gassendi's version of the mechanical philosophy rivaled that of Descartes, with whom he engaged in an extensive controversy following the publication of the latter's Meditations in 1641.

Gassendi's philosophy was promulgated in England in several books published in the 1650s by Walter Charleton (16201707) and in France by François Bernier's Abrégé de la philosophie de Gassendi (1674). A younger generation of natural philosophers, including Robert Boyle (16271690) and Isaac Newton (16421727), who accepted the mechanical philosophy, faced a choice between Gassendi's atomism and Descartes's plenism. John Locke (16321704) absorbed many of Gassendi's ideas about epistemology and ethics, which thus had considerable influence on the subsequent development of empiricist epistemology and liberal political philosophy.

See also Aristotelianism ; Astronomy ; Boyle, Robert ; Cartesianism ; Charleton, Walter ; Descartes, René ; Determinism ; Empiricism ; Epistemology ; Free Will ; Galileo Galilei ; Hobbes, Thomas ; Humanists and Humanism ; Locke, John ; Logic ; Mechanism ; Natural Philosophy ; Neoplatonism ; Newton, Isaac ; Philosophy ; Physics ; Political Philosophy ; Reason ; Scientific Method ; Scientific Revolution ; Skepticism: Academic and Pyrrhonian .


Primary Sources

Gassendi, Pierre. Opera Omnia. Lyon, 1658; reprinted Stuttgart-Bad Canstatt, 1964.

. The Selected Works of Pierre Gassendi. Translated by Craig Brush. New York, 1972.

Secondary Sources

Osler, Margaret J. Divine Will and the Mechanical Philosophy: Gassendi and Descartes on Contingency and Necessity in the Created World. Cambridge, U.K., and New York, 1994.

Sarasohn, Lisa T. Gassendi's Ethics: Freedom in a Mechanistic Universe. Ithaca, N.Y., 1996.

Margaret J. Osler

Gassendi, Pierre

views updated May 23 2018


Philosopher whose works influenced the growth of mechanics and theoretical astronomy from galileo to Newton; b. Champtercier, Jan. 22, 1592; d. Paris, Oct. 24, 1655.

Exposed to, but not convinced by, the Aristotelianism presented during his student days at the University of Aix (160912), the philosophically hungry Gassendi taught rhetoric in the college at Digne. In 1614 he received minor clerical orders, was granted a doctorate in theology by the University of Avignon, and was elected canon-theologian of the cathedral chapter at Digne. In 1616 Gassendi joined the philosophical faculty of the Royal Bourbon College at Aix and was ordained a priest at Marseilles. Gassendi's courses at Aix were ambiguous, for he countered each presentation of an "official" Aristotelian thesis with objections calculated to weaken, if not destroy, its acceptability. When in 1621 the Bourbon College was entrusted to the Jesuits, Gassendi returned to Digne.

In 1624 at Grenoble, en route to Paris on chapter business, Gassendi published the first of his projected seven Unpopular Essays against the Aristotelians (Exercitationes paradoxicae adversus Aristoteleos ). At Paris Gassendi consolidated an intimate friendship with Marin Mersenne, who, fearful of the inroads of magical pseudonaturalism, counseled Gassendi to discontinue the Exercitationes series and search instead for a sounder philosophy to fill the intellectual vacuum created by the impending dissolution of Aristotelianism. Gassendi chose Epicurus to replace Aristotle. To explore and expound the philosophy of Epicurus, as compatible with both the demands of orthodox Christian faith and the needs of the new science, thenceforth became Gassendi's goal as scholar and scientist.

Gassendi's choice entailed two consequences: (1) epoche and (2) acceptance of both atoms and the void. The first consequence, as a conscientious refusal to commit oneself to any one of several competing theories, allowed Gassendi, in his 1643 Disquisitio metaphysica, to controvert powerfully the purportedly certain deductive system of Descartes's 1641 Meditationes de prima philosophia and to write (indeterminatamente ) another book, his 1647 Institutio astronomica. Galileo had received papal authorization for such a book, but instead had produced his passionately partisan 1632 Dialogo in defense of Copernicus. Gassendi's espousal of atomism exorcised that theory from the curse of popular prejudice and made it respectable in a Christian milieu, but scientific development of it needed the quantitative and experimentally analytic results of Robert Boyle, not the qualitative and imaginatively synthetic descriptions of Gassendi's "compounds." Gassendi's acceptance of the void, however, allowed him to set the mechanics of Galileo's 1638 Discorsi into an isotropically neutral space, and hence to publish for the first time (1649) a scientifically adequate formulation of the principle of inertia.

Bibliography: Opera omnia, ed. h. l. habert de montmor and f. henri, 6 v. in 4 (Lyons 165875); repr. in 6 v. (Stuttgart 1964), introd. t. gregory. b. rochot, ed., Pierre Gassendi: Sa vie et son oeuvre (Paris 1955). Comité du Tricentenaire de Gassendi, Actes du Congrés du Tricentenaire de Pierre Gassendi (Paris 1957). t. gregory, Scetticismo ed empirismo: Studio su Gassendi (Bari 1961). j. t. clark, "P. G. and the Physics of Galileo," Isis 54 (1963) 352370.

[j. t. clark]

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