Jean Le Rond d’Alembert Biography

(Mathematician, Philosopher)

Birthday: November 16, 1717 (Scorpio)

Born In: Paris, France

A great mathematician, philosopher and music theoretician, Jean Le Rond d’Alembert was among the most influential men of his time. His “Traité de dynamique”, in which he expounded his own laws of motion, is one of his notable works. He did some outstanding developments in the field of mathematics, particularly, in the ‘foundations of mathematics’. The “d’Alembert theorem” and the “ratio tests” (a test to check if a “series” unites) developed by him is followed in mathematics even now. He expressed a fair amount of interest in physics as well, and thus, came up with the “d’Alembert operator”, which is vital in modern theoretical physics. As a mathematician and physicist, he received reasonable reputation and was therefore chosen to edit articles on mathematics and physics for the French encyclopedia. Later he turned to philosophy, literature and music. Some his philosophical works were highly praised in the salons he attended. Read on to know more about this genius.

Quick Facts

French Celebrities Born In November

Also Known As: Jean-Baptiste le Rond d'Alembert

Died At Age: 65


father: Louis-Camus Destouches

mother: Claudine Guérin de Tencin

Born Country: France

Physicists Philosophers

Died on: October 29, 1783

place of death: Paris, France

City: Paris

Childhood & Early Life

Jean le Rond D’Alembert was born Jean-Baptiste le Rond d'Alembert, on November 16, 1717, in Paris France, to Claudine Guérin de Tencin and Louis-Camus Destouches. His mother was a writer, while his father was an artillery officer in the French army. However, he was not raised by his parents. His father was abroad when Jean was born, and his mother abandoned the baby, leaving him outside a Church. It is said that Jean was named after the church’s patron saint.

However, when his father returned back to Paris, he brought Jean home and put him in the care of one of his friend’s wife. He did not want to be officially recognized as Jean’s father. However, he paid for Jean’s education in secret.

Jean was enrolled in a private school first, where he excelled in academics. Following the completion of his early education, he enrolled at a college affiliated with the University of Paris and received higher education in philosophy, law and arts. He graduated with a Bachelor of Arts degree in 1735.

His teachers at the university first wanted him to study theology, after observing his interests in the field. However, Jean wanted to pursue law and he became an advocate by 1738.  However, his interest in law was only limited until he studied it. He never practised law, which was a highly respected profession. By then, his interest had peaked in mathematics and he began self-studying it. He also took a one-year training in medicine. But he wanted to pursue mathematics for his career. He took some lessons from mathematicians, but mostly he was self-taught.

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By his mid-20s, he had excelled in the field of mathematics and made his first mark on the field in 1739, when he read his first paper to the Academy of Sciences. He submitted another paper in 1740, which was based on fluid mechanics. He wanted to become a part of the academy but had several failed attempts at joining it.

He ended up becoming a member of the Academy of Sciences in 1741 and two years later, he published his first important treatise, which was based on Newton’s third law of motion. In what is also known as d’Alembert’s Principle, he stated that Newton’s third law of motion equally applies to bodies that are in motion and the bodies that are rigidly fixed. Thus, he discovered his own laws of motion.

Many more mathematical works followed rapidly as he worked on the theories of equilibrium and the motion of fluids. In 1747, he had yet another major career breakthrough when he developed partial differential equations. He thus won a prize at the Berlin Academy and was also accepted as a member.

He further published Recherches sur les cordes vibrantes, in which he applied his new calculus theories to the problems of vibrating string. He further worked on applying his mathematical findings to any physical body, of any shape.

Towards the late 1940s, he made yet another discovery, written in the paper titled Recherches sur la précession des équinoxes et sur la nutation de l’axe de la terre. In the paper, he wrote his explanation for the earth’s orbit’s gradually changing positions.

Later in 1952, he published yet another paper, in which he wrote his new ideas and discoveries. He also researched integral calculus and published his findings in the Memoirs of Berlin Academy. This contribution to mathematical science is considered huge as some of his equations are still applied to this day.

He is also known for his works on music theories, from which his first interaction happened in the late 1940s when he was asked to review a memoir submitted by the musician Jean-Philippe Rameau. He praised Rameau’s works and called them scientific. He also stated that Rameau’s theories of music were in coherence with his own theories. A few years later, he analyzed the complete works of the musician in which he found out that his music composition was based on mathematical science.

Rameau believed that music was a science that works on only one principle. Jean polished his theories and theorized that one single principle was not enough to derive all the music in the world. Over time, the two men turned on each other and Jean and Rameau engaged in a bitter war of words, which led to the end of their friendship.

By the mid-1940s, he had become an influential thinker in French society. He was asked to be involved in the creation of Encyclopedie in 1945 for the first time. In 1947, he was named the co-editor of Encyclopedie and was charged with overlooking the publication of mathematical and scientific articles. However, he ended up writing the highly controversial ‘Geneve’, a non-scientific opinion piece on religion. It led to protests and ended with Jean’s resignation from the position of the co-editor.

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Influenced by this and willing to share his philosophical observations, he wrote Essai sur les éléments de philosophie: ou sur les principes des connaissances humaines in 1759. It was a highly popular article that laid out his philosophical principles and methods on topics such as metaphysics, language theory, science and epistemology.

However, his most important philosophical work is considered to be Preliminary Discourse to Encyclopaedia, which he wrote in 1751. In the document, he wrote about the enterprise of encyclopaedia and also traced the evolution of human thought throughout history.

He had also gained a follower in the Prussian king Frederick II, who constantly tried to persuade him to preside the Berlin Academy. Jean didn’t take the position but he advised the king many times on how to run the academy and appoint new members.

In the 1760s, he was also requested by Empress Catherine II of Russia to tutor her son. But he refused to move to Russia, as he liked the intellectual environment of Paris.

In April 1772, he was made the permanent secretary of the Academy of Sciences.

Personal Life & Death

Jean le Rond D’Alembert’s health began deteriorating in the mid-1760s, following which he left his foster mother’s home and shifted with Julie de Lespinasse, who was her admirer.  He was a regular visitor to her salon and was a man of high standing there. They fell in love with each other and also had an intimate relationship.

After her death in 1776, he shifted to the apartment given to him as the secretary of the Academy of Sciences. He passed away from a urinary bladder infection, on October 29, 1783.

He was known as a kind man who never wished for wealth and led a simple life.

He was a non-believer and hence, he was buried in an unmarked grave, in Paris.

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