Born in Paris, d'Alembert was thenatural son of the writerClaudine Guérin de Tencin and the chevalierLouis-Camus Destouches, anartillery officer. Destouches was abroad at the time of d'Alembert's birth. Days after birth his mother left him on the steps of theSaint-Jean-le-Rond de Paris [fr] church. According to custom, he was named after thepatron saint of the church. D'Alembert was placed in anorphanage forfoundling children, but his father found him and placed him with the wife of aglazier, Madame Rousseau, with whom he lived for nearly 50 years.[6] She gave him little encouragement. When he told her of some discovery he had made or something he had written she generally replied,
You will never be anything but a philosopher—and what is that but an ass who plagues himself all his life, that he may be talked about after he is dead.[7]
Destouches secretly paid for the education of Jean le Rond, but did not want hispaternity officially recognised.
D'Alembert first attended a private school. The chevalier Destouches left d'Alembert anannuity of 1,200livres on his death in 1726. Under the influence of the Destouches family, at the age of 12 d'Alembert entered theJansenistCollège des Quatre-Nations (the institution was also known under the name "Collège Mazarin"). Here he studied philosophy, law, and the arts, graduating asbaccalauréat en arts in 1735.
In his later life, d'Alembert scorned theCartesian principles he had been taught by theJansenists: "physical promotion, innate ideas and the vortices". The Jansenists steered d'Alembert toward anecclesiastical career, attempting to deter him from pursuits such as poetry andmathematics. Theology was, however, "rather unsubstantial fodder" for d'Alembert. He entered law school for two years, and was nominatedavocat in 1738.
He was also interested in medicine and mathematics. Jean enrolled first as Jean-Baptiste Daremberg and subsequently changed his name, perhaps for reasons of euphony, to d’Alembert.[8]
Later, in recognition of d'Alembert's achievements, Frederick the Great of Prussia proposed the name "d'Alembert" for a suspected (but non-existent) moon of Venus, however d'Alembert refused the honor.[9]
In July 1739 he made his first contribution to the field of mathematics, pointing out the errors he had detected inAnalyse démontrée (published 1708 byCharles-René Reynaud) in a communication addressed to theAcadémie des Sciences. At the timeL'analyse démontrée was a standard work, which d'Alembert himself had used to study thefoundations of mathematics. D'Alembert was also aLatin scholar of some note and worked in the latter part of his life on a translation ofTacitus, for which he received wide praise including that ofDenis Diderot.
In 1740, he submitted his secondscientific work from the field offluid mechanicsMémoire sur la réfraction des corps solides, which was recognised byClairaut. In this work d'Alembert theoretically explainedrefraction.
In 1743, he published his most famous work,Traité de dynamique, in which he developed his ownlaws of motion.[12]
When theEncyclopédie was organised in the late 1740s, d'Alembert was engaged as co-editor (for mathematics and science) with Diderot, and served until a series of crises temporarily interrupted the publication in 1757. He authored over a thousand articles for it, including the famousPreliminary Discourse. D'Alembert "abandoned the foundation ofMaterialism"[13] when he "doubted whether there exists outside us anything corresponding to what we suppose we see."[13] In this way, d'Alembert agreed with theIdealistBerkeley and anticipated thetranscendental idealism ofKant.[citation needed]
In 1754, d'Alembert was elected a member of theAcadémie des sciences, of which he became Permanent Secretary on 9 April 1772.[14]
In 1757, an article by d'Alembert in the seventh volume of theEncyclopedia suggested that the Geneva clergymen had moved fromCalvinism to pureSocinianism, basing this on information provided byVoltaire. The Pastors of Geneva were indignant, and appointed a committee to answer these charges. Under pressure fromJacob Vernes,Jean-Jacques Rousseau and others, d'Alembert eventually made the excuse that he considered anyone who did not accept the Church of Rome to be a Socinianist, and that was all he meant, and he abstained from further work on the encyclopaedia following his response to the critique.[15]
D'Alembert's first exposure to music theory was in 1749 when he was called upon to review aMémoire submitted to the Académie byJean-Philippe Rameau. This article, written in conjunction withDiderot, would later form the basis of Rameau's 1750 treatiseDémonstration du principe de l'harmonie. D'Alembert wrote a glowing review praising the author's deductive character as an ideal scientific model. He saw in Rameau's music theories support for his own scientific ideas, a fully systematic method with a strongly deductive synthetic structure.
Two years later, in 1752, d'Alembert attempted a fully comprehensive survey of Rameau's works in hisEléments de musique théorique et pratique suivant les principes de M. Rameau.[17] Emphasizing Rameau's main claim that music was a mathematical science that had a single principle from which could be deduced all the elements and rules of musical practice as well as the explicit Cartesian methodology employed, d'Alembert helped to popularise the work of the composer and advertise his own theories.[17] He claims to have "clarified, developed, and simplified" the principles of Rameau, arguing that the single idea of thecorps sonore [fr] was not sufficient to derive the entirety of music.[18] D'Alembert instead claimed that three principles would be necessary to generate the majormusical mode, the minor mode, and the identity ofoctaves. Because he was not a musician, however, d'Alembert misconstrued the finer points of Rameau's thinking, changing and removing concepts that would not fit neatly into his understanding of music.
Although initially grateful, Rameau eventually turned on d'Alembert while voicing his increasing dissatisfaction withJ. J. Rousseau'sEncyclopédie articles on music.[19] This led to a series of bitter exchanges between the men and contributed to the end of d'Alembert and Rameau's friendship. A long preliminary discourse d'Alembert wrote for the 1762 edition of hisElémens attempted to summarise the dispute and act as a final rebuttal.
D'Alembert also discussed various aspects of the state of music in his celebratedDiscours préliminaire ofDiderot'sEncyclopédie. D'Alembert claims that, compared to the other arts, music, "which speaks simultaneously to the imagination and the senses," has not been able to represent or imitate as much of reality because of the "lack of sufficient inventiveness and resourcefulness of those who cultivate it."[20] He wanted musical expression to deal with all physical sensations rather than merely the passions alone. D'Alembert believed that modern (Baroque) music had only achieved perfection in his age, as there existed no classicalGreek models to study and imitate. He claimed that "time destroyed all models which the ancients may have left us in this genre."[21] He praises Rameau as "that manly, courageous, and fruitful genius" who picked up the slack left byJean-Baptiste Lully in the French musical arts.[22]
In France, thefundamental theorem of algebra is known as the d'Alembert/Gauss theorem, as an error in d'Alembert's proof was caught by Gauss.
He also created hisratio test, a test to determine if aseries converges.
TheD'Alembert operator, which first arose in D'Alembert's analysis of vibrating strings, plays an important role in modern theoretical physics.
While he made great strides in mathematics and physics, d'Alembert is also famously known for incorrectly arguing inCroix ou Pile that theprobability of a coin landing heads increased for every time that it came up tails. In gambling, the strategy of decreasing one's bet the more one wins and increasing one's bet the more one loses is therefore calledtheD'Alembert system, a type ofmartingale.
Diderot portrayed d'Alembert inLe rêve de D'Alembert (D'Alembert's Dream), written after the two men had become estranged. It depicts d'Alembert ill in bed, conducting a debate on materialist philosophy in his sleep.
D'Alembert, Jean Le Rond (1747b). "Suite des recherches sur la courbe que forme une corde tenduë mise en vibration (Further researches on the curve that a tense cord forms [when] set into vibration)".Histoire de l'académie royale des sciences et belles lettres de Berlin. Vol. 3. pp. 220–249.
^Israel 2011, p. 115: "D'Alembert, though privately an atheist and materialist, presented the respectable public face of 'la philosophie' in the French capital while remaining henceforth uninterruptedly aligned with Voltaire."
^Force & Popkin 1990, p. 167: "Unlike the French and English deists, and unlike the scientific atheists such as Diderot, d'Alembert, and d'Holbach, such English scientists as David Hartley and Joseph Priestley presented their scientific theories as evidence for their scriptural views."
^Horowitz 1999, pp. 52–53: "In positive theory there was a wide divergence between Voltaire's panpsychic deism and Diderot's physiological materialism, or d'Alembert's agnostic positivism and Helvetius' sociological materialism."
Bernard, Jonathan W. (1980). "The Principle and the Elements: Rameau's Controversy with D'Alembert".Journal of Music Theory.24 (1):37–62.doi:10.2307/843738.JSTOR843738.
Christensen, Thomas (1989). "Music Theory as Scientific Propaganda: The Case of D'Alembert's Élémens [sic] De Musique".Journal of the History of Ideas.50 (3):409–27.doi:10.2307/2709569.JSTOR2709569.
Elsberry, Kristie Beverly (1984).Elémens de musique théorique et pratique suivant les principles de M. Rameau: an Annotated New Translation and a Comparison to Rameau's Theoretical Writings (PhD Dissertation). Florida State University.
Force, James E.; Popkin, Richard Henry (1990).Essays on the Context, Nature, and Influence of Isaac Newton's Theology. Springer.ISBN9780792305835.
