Pierre Gassendi
French mathematician, philosopher, and scientist
Gassendi also spelled Gassend
born Jan. 22, 1592, Champtercier, Provence, France
died Oct. 24, 1655, Paris
Main
French philosopher, scientist, and mathematician, who
revived Epicureanism as a substitute for Aristotelianism,
attempting in the process to reconcile mechanistic atomism
with the Christian belief in an infinite God.
Early life and career
Born into a family of commoners, Gassendi received his early
education at Digne and Reiz. He studied at universities in
Digne and Aix-en-Provence and received a doctorate in
theology at the university in Avignon in 1614. After being
ordained a priest in 1616 he was appointed professor of
philosophy at Aix-en-Provence. There he delivered critical
lectures on the thought of Aristotle from 1617 to 1622, when
the new Jesuit authorities of the university, who
disapproved of Gassendi’s anti-Aristotelianism, compelled
him to leave. Gassendi’s work Exercitationes paradoxicae
adversus Aristoteleos (“Paradoxical Exercises Against the
Aristotelians”), the first part of which was published in
1624, contains an attack on Aristotelianism and an early
version of his mitigated skepticism. Gassendi thereafter
engaged in many scientific studies with his patron,
Nicolas-Claude Fabri de Peiresc, until the latter’s death in
1637. A considerable portion of his researches during this
period involved astronomical observations, including his
discovery in 1631 of the perihelion of Mercury (the point of
the planet’s closest approach to the Sun).
Skepticism and atomism
In 1641 the theologian and mathematician Marin Mersenne
invited Gassendi and several other eminent thinkers to
contribute comments on the manuscript of René Descartes’s
Meditations (1641); Gassendi’s comments, in which he argued
that Descartes had failed to establish the reality and
certainty of innate ideas, were published in the second
edition of the Meditations (1642) as the fifth set of
objections and replies. Gassendi enlarged upon these
criticisms in his Disquisitio metaphysica, seu duitationes
et instantiae adversus Renati Cartesii metaphysicam et
responsa (1644; “Metaphysical Disquisition; or, Doubts and
Instances Against the Metaphysics of René Descartes and
Responses”).
In 1645 Gassendi was appointed professor of mathematics
at the Collège Royal in Paris. During the remainder of the
decade he published a work on the new astronomy, Institutio
astronomica juxta hypotheseis tam veteram quam Copernici et
Tychonis Brahei (1647; “Astronomical Instruction According
to the Ancient Hypotheses as Well as Those of Copernicus and
Tycho Brahe”), as well as two of his three major works on
Epicurean philosophy, De vita et moribus Epicuri (1647; “On
the Life and Death of Epicurus”) and Animadversiones in
decimum librum Diogenis Laertii, qui est de vita, moribus,
placitisque Epicuri (1649; “Observations on Book X of
Diogenes Laërtius, Which Is About the Life, Morals, and
Opinions of Epicurus”).
In his final Epicurean work, Syntagma philosophicum
(“Philosophical Treatise”), published posthumously in 1658,
Gassendi attempted to find what he called a middle way
between skepticism and dogmatism. He argued that, while
metaphysical knowledge of the “essences” (inner natures) of
things is impossible, by relying on induction and the
information provided by “appearances” one can acquire
probable knowledge of the natural world that is sufficient
to explain and predict experience. Adopting a view
characteristic of ancient Skepticism, Gassendi held that
experienced events can be taken as signs of what is beyond
experience. Smoke suggests fire, sweat suggests that there
are pores in the skin, and the multitude of events suggests
that there is an atomic world underlying them. The best
theory of such a world, in Gassendi’s opinion, is the
ancient atomism expounded by Epicurus (341–270 bce),
according to which atoms are eternal, differently shaped,
and moving at different speeds. Gassendi argued that such
atoms must have some of the physical features of the visible
objects they constitute, such as extension, size, shape,
weight, and solidity. The atoms collide and agglomerate,
resulting in events in the perceptible world. A mechanical
model of atomic movement and agglomeration, ultimately based
on experience, would allow one to discover probabilistic
empirical laws, to make predictions, and to explain
relationships between different kinds of phenomena. Because
the phenomenal world is thus related to the atomic world,
there is no need to explain events in terms of purposes,
goals, or final causes, as in Scholastic and Aristotelian
teleology.
Gassendi believed that there was no conflict between his
mechanistic atomism and the doctrines of Roman Catholicism;
indeed, he took pains to emphasize their compatibility.
Although he was a heliocentrist, he presented his
astronomical views in a way that made them at least
superficially consistent with the teachings of the church,
which had condemned Galileo for his heliocentrism in 1633.
Although Gassendi’s atomism was as complete an account of
nature as any other scientific theory of its time, it was
eventually replaced by the physics of Sir Isaac Newton. No
important discoveries are attributed to Gassendi’s
scientific program.
Religious and moral views
Gassendi rejected the Epicurean account of the human soul,
according to which it is material but composed of lighter
and more subtle atoms than those of other things. Souls are
genuinely immaterial, and their existence is known through
faith. Likewise, his theology, unlike Epicurus’s, did not
conceive of God as a material body. God’s existence is
proved by the harmony evident in nature. Following Epicurus,
Gassendi held that the proper goal of human life is
happiness, which consists in the peace of the soul and the
absence of bodily pain.
It has long been debated whether Gassendi was really a
secret libertine—a freethinker in matters of religion and
morals. Although he was a close associate of some notorious
religious skeptics and even took part in their retreats, he
was also good friends with some leading church figures, such
as the theologian and mathematician Marin Mersenne. Indeed,
Gassendi and Mersenne had quite similar views about science
and its foundations. Gassendi’s associations with a wide
range of other intellectual figures, including Thomas Hobbes
and Blaise Pascal, lend themselves to varied
interpretations.
Influence and assessment
In 1648 Gassendi resigned his post at the Collège Royal
because of poor health. After nearly five years in Provence
he returned to Paris in 1653, taking up residence in the
house of his new patron, Henri-Louis Habert, lord of Montmor.
He died there two years later.
Gassendi’s ideas were extremely influential in the 17th
century. Although his works were originally published as
huge Latin tomes, a French abridgement of them appeared in
the second half of the century, as did English translations
of various excerpts. His ideas were taught in Jesuit schools
in France, in English universities, and even in newly
founded schools in North America. Because Gassendi’s
epistemological views seem to be echoed in major sections of
John Locke’s Essay Concerning Human Understanding (1690),
one of the founding works of British empiricism, some
scholars have concluded that Locke was directly influenced
by Gassendi. It is interesting to note in this connection
that the Syntagma was published in English in Thomas
Stanley’s History of Philosophy (1655–62), a work that Locke
knew. Locke also met some of Gassendi’s disciples during his
exile in France.
At the turn of the 21st century there was growing
interest in Gassendi’s critique of Cartesianism, and his
scientific researches were shedding new light on the early
development of botany, geology, and other fields. He is now
regarded as an original thinker of the first rank.
