Diderot, Denis (1713–1784) French philoso-
pher, novelist, and critic
Diderot was born in Langres and received his master’s
degree from the University of Paris in 1732. He spent
the next 10 years engaged in assorted occupations,
including teaching and writing sermons for a fee. He
also immersed himself in the study of mathematics, lit-
erature, and languages and translated a number of
English works into French. In 1746 Diderot published
his Pensées philosophiques (Philosophical Thoughts),
which contained a bold critique of Christianity. That
same year, at the request of his friend, the mathemati-
cian Jean Le Rond d’Alembert, Diderot became a con-
tributing editor to the monumental Encyclopédie,a
multivolume review of the arts and sciences of the day
whose guiding perspective was a faith in the progress
of the human mind inspired by RATIONALISM. Other
contributors included the most prominent philoso-
phers of the period, such as VOLTAIRE, ROUSSEAU, d’Hol-
bach, and Turgot.
Diderot’s own philosophical orientation was ratio-
nalist. He was an advocate of the scientific method and
developed a version of materialism that held the uni-
verse to be a purely physical system composed of ele-
mentary material particles containing energy. More-
over, in the Lettre sur les aveugles(Letter on the Blind)
of 1749, Diderot presented an evolutionary theory for
the development of organisms, including the influence
of hereditary factors. Because this treatise contained a
passage that questioned the notion of a divine purpose
in nature and the existence of an intelligent God,
Diderot was arrested by the authorities and imprisoned
at Vincennes for three months.
Diderot’s materialism led him to conceive of mo-
rality as a product of both physiology and cul-
ture. Human beings are decidedly natural animals,
possessed of basic biological needs and driven by emo-
tions and sensations. But they also possess imagina-
tion, memory, and intelligence and are able to adapt to
different environments and modify their beliefs and
habits. Through an appropriate education, it is pos-
sible to cultivate our national capacities and
to live a life of virtue and JUSTICEthat may bring hap-
piness.
Diderot was also a prominent critic of the social
and political institutions of the day, believing them to
be unnecessarily restrictive and conservative. In a
number of writings, including articles in the Ency-
clopédie,Diderot strongly supported the ideals of mod-
ern DEMOCRACY against the traditional authority of
royalty. He asserted that “the people” are the true
source of SOVEREIGNTY, and therefore they should
choose representatives and determine legislation and
the operation of government. To prevent tyranny,
church and state must be separated. In addition,
Diderot actively campaigned for the elimination of
capital punishment and other forms of inhumane pun-
ishment. Overall, Diderot’s contribution to the intellec-
tual development of the ENLIGHTENMENTis significant,
primarily due to the publicity his work on the Ency-
clopédie, brought to the philosophical and political
ideas of the period.Further Reading
Furbank, P. N. Diderot: A Critical Biography.New York: Knopf,
1992.discrimination
A concept prevalent in the 20th century, held espe-
cially by American LIBERALS, that claims an injustice is
done by society when individuals of equal ability are
treated unequally. This assumes that differences in
race, gender, disability, or sexual orientation do not86 Diderot, Denis
German Nazi dictator Adolf Hitler, Russian dictator Joseph Stalin,
Italian dictator Benito Mussolini, and Louisiana politician Huey
Long are dressed as Napoleon Bonaparte. Painting by Miguel
Covarrubias, 1933.(LIBRARY OFCONGRESS)