Jules Dupuit in his time

Jules Dupuit was a peerless figure of the mid-nineteenth century with a double characteristic: his education, his carrier and his works made him a prominent figure in the lasting tradition of engineers-economists and, at the same time, his involve­ment in the liberal institutions undoubtedly placed him at the heart of the French liberal school.

A representative figure of “ingenieur economiste”

Arsene Jules Emile Juvenal Dupuit was born on 18 May 1804 in Fossano (Pied­mont, Italy). His curriculum epitomises the typical traits of the French school of “ingenieur-economistes”: after his education in the prestigious Ecole Royale Polytechnique and the Ecole Royale des Ponts et Chaussees,¹ he began his career as a simple engineer specialised in the management of canals and the mainte­nance of roads in the French department of Sarthe. At the beginning of the 1830s, he devoted himself to technical studies concerning the wear of metalled roads and the friction of wagons on railways. His early works were remarked by his hierarchy and he became second-class Chief engineer of the Marne (1842) and first-class Chief engineer in Maine-et-Loire (1849),^{[59] [60] where he was alternately in charge of road maintenance, building and management of bridges, hydraulic studies and transport policy. After being appointed in Paris (1850) as a chief engineer of the Prefect of the department of Seine and then General Inspec­tor (1855) and member of the Conseil general des ponts et chaussees (1855),[61] Dupuit progressively became a public figure. He crossed swords with Baron Haussmann[62] while leading the road services of Paris and multiplied interven­tions outside his original field of competence. His career as an engineer slowed down with the reduction of his technical duties and his involvement in economic and social debates increased: he started a kind of “second life” and from a field engineer he became a man fully involved in the debates of his time (Simonin and Vatin 2016, 20).[63]}

Contrarily to Cournot, Dupuit belonged to the lasting tradition of French engi­neers, whose heritage can be traced to the soldier-engineer Sebastien Le Prestre de Vauban (1633-1707).

Apart from his technical excellence and public-oriented interests, Dupuit - like numerous other French economists - also acquired specific economic skills on the job, such as being able to balance expenditure and resources for any road or canal project, to draw up quotes or to manage a budget. In short, he learned how to think as an economist, even if he did not benefit from any specific training in econom­ics.^[64] In their everyday work, Jules Dupuit and the other engineers of the Corps des ponts et chaussees had to solve practical problems closely linked to econom­ics. They also had to make decisions complying with the highest interest of soci­ety: the calculation of costs and benefits was systematised to settle the relevance of any public investment in communication networks. Every time civil engineers were responsible for public works, they had to follow a comprehensive approach in a broad (technical, economic, financial) perspective, much beyond the scope of engineering science: when questioning the practicability and desirability of a given bridge, canal or roads maintenance task, certain economic questions immediately arose: should the user be charged for the costs? Should this charge be equal or dif­ferentiated? Should the flow of users and the size of their vehicles be regulated? In this way, his practical experience as an engineer a la franςaise certainly set Dupuit on the path to economic calculation and then economic analysis (Vatin 2003).

Due to this specific French background, Dupuit was not the only civil engi­neer to show interest in political economy and to participate in (more or less fre­quent) discussions with economists. Numerous engineers in their everyday work raised the same type of questions as Dupuit. Reciprocally, the Societe d’economie politique included numerous engineers, from the most well-known, like Michel Chevalier (1806-1879), Ernest Lame Fleury (1823-1903) or Roger de Fontenay (1809-1891), to more modest figures such as Benjamin Nadault de Buffon, Pierre- Jules Mahyer or Felix-Jacques Obry de Labry. But, among them, Dupuit was the only one to show such a prominent analytical singularity. Etner (1987) remarks that these engineers were not really aware that they formed a specific group: this perspective only surfaced some decades later, when Dupuit’s contributions were recognised by prestigious heirs as seminal works for their intellectual tradition. Later on, historians of economic thought regarded Jules Dupuit as the founding father of this school of thought.

Dupuit and the French liberal economists

Dupuit’s intellectual development shows a second essential feature: in the 1850s, in addition to his activities as chief engineer, he gradually succeeded in gaining an important stature within the liberal group. As an economist, Dupuit dealt with the liberal legacy linked to several names he most often quoted: Adam Smith, Jean-Baptiste Say, Antoine-Louis-Claude Destutt de Tracy and Pellegrino Rossi (to whom he regularly paid tribute): they inspired his views, especially on value theory. Nevertheless, these references are perhaps a simple “rhetoric trick” (Vatin 2003) since Dupuit, like the other contemporary French engineers, was accustomed to reading political economy, especially the greatest authors.

Dupuit’s involvement in economic debates increased in the second half of his career. He gradually became a full member of the most influential intellectual soci­eties of his time, in which the liberal economists exerted a strong influence: the Paris Societe d’economie politique and the Societe de statistique de Paris, in which he discussed topical economic, social and technical issues with a wide variety of other members (professional economists, merchants, manufacturers, bankers, poli­ticians, philosophers, engineers, etc.). His most important involvement was with the Societe d’economie politique, one of the main channels of dissemination of liberal ideas in France.^[65] He started to attend its meetings in 1849 and multiplied his interventions during the following decade. In 1849 he wrote his first article for the Journal des economistes and dozens of articles were to follow on a large variety of topics. But he never published any treatise which might have gathered all his contributions together.

Dupuit finally ended up belonging to the inner circle of liberal economists. In this respect, his intellectual trajectory is outstanding compared to many other engineers^[66] who participated in a more distant and irregular way in the debates within the Paris group. He was strongly supported by Joseph Garnier (1813-1881), a powerful liberal figure, while his main enemies were Roger de Fontenay, who opposed him on value theory, and Leon Walras (1834-1910), whose main criticism regarded his analysis of surplus.^[67] It must be noted that Dupuit never mentioned Cournot’s name in his writings in spite of the proximity of their investigations and the apparent similarity of their reasoning - but there is no evidence to prove that he either ignored or knew the mathematician’s works.

Dupuit’s inclusion in the liberal group was, however, paradoxical. On the one hand, the liberal economists mostly ignored the originality of his developments on public economics, and Dupuit did not share his views as an engineer with his liberal contemporaries.

His interactions with his liberal contemporaries got worse from 1860 onwards as his positions became more and more opinionated and radical. Only Joseph Garnier remained a constant support for him, while many other Societe members were increasingly irritated by his later opinions. In the twilight of his life, his rela­tionships with the liberal economists deteriorated so badly that, in 1863, he failed to become the Vice Chairman of the Societe d’economie politique - after having been in contact with Frederic Le Play (1806-1882), he even ended up becom­ing a member the same year of the Societe internationale des etudes pratiques d’economie sociale (more often called Societe d’economie sociale), considered as the opponent of the liberals.

The strength and novelty of Dupuit’s analyses were subsequently appreci­ated at their true value.^[71] If many marginalist authors credited Dupuit for major improvements in economic analysis,^[72] his theoretical contributions to the field were belatedly rediscovered thanks to the 1933 reprint - by Luigi Einaudi and Mario De Bernardi - of some of his most famous works. Rene Roy and Franςois Divisia strove to bring Dupuit’s thought up to date on the occasion of the centenary of his most reputed essay, “De la mesure de l’utilite des travaux publics”. But now the present readers can profitably enjoy his complete economic works edited in 2009 by Yves Breton and Gerard Klotz.^[73]

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