Jules Dupuit (18 May 1804 - 5 September 1866) was a French civil engineer and economist. May 18 is the 138th day of the year in the Gregorian Calendar (139th in leap years). ... 1804 was a leap year starting on Sunday (see link for calendar). ... September 5 is the 248th day of the year (249th in leap years). ... 1866 is a common year starting on Monday. ... The term civil engineer refers to an individual who practices civil engineering. ... An economist is someone who studies Economics. ...

He was born in Fossano, Italy then under the rule of Napoleon Bonaparte. At the age of ten he emigrated to France with his family where he studied in Versailles - winning a Physics prize at graduation. He then studied in the Ecole Polytechnic as a civil engineer. He gradually took on more responsibility in various regional posts. He received a Légion d'honneur in 1843 for his work on the French road system, and shortly after moved to Paris. He also studied flood management in 1848 and supervised the construction of the Paris sewer system. He died in Paris. Bonaparte as general Napoleon Bonaparte ( 15 August 1769 – 5 May 1821) was a general of the French Revolution and was the ruler of France as First Consul (Premier Consul) of the French Republic from November 11, 1799 to May 18, 1804, then as Emperor of the French (Empereur des Français... Versailles, formerly the unofficial capital city of the kingdom of France, is now a wealthy suburb of Paris and is still an important administrative and judicial center. ... French Legion of Honour The Légion dhonneur (Legion of Honor (AmE) or Legion of Honour (ComE)) is an Order of Chivalry awarded by the President of France. ... The Eiffel Tower has become a symbol of Paris throughout the world. ...

Engineering questions led to his interest in economics, a subject in which he was self-taught. His 1844 article was concerned with deciding the optimum toll for a bridge. It was here that he introduced his curve of diminishing marginal utility. As the quantity of a good consumes rises, the marginal utility of the good declines for the user. So the lower the toll (lower marginal utility), the more people who would use the bridge (higher consumption). Conversely as the quantity rises (people allowed on the bridge), the willingness of a person to pay for that good (the price) declines. The word toll has several meanings. ... // A Abundance Abundance is the state in which there is more than enough. ...

Thus, the concept of diminishing marginal utility should translate itself into a downward-sloping demand function. In this way he identified the demand curve as the marginal utility curve. This was the first time an economist had put forward a theory of demand derived from marginal utility. Although not the first time that the demand curve had been drawn, it was the first time that it had been proved rather than asserted.

Dupuit's logic was suspect in that it skipped over the fact that marginal utility is particular to an individual, while market demand is an aggregate. Nothing was said on the interpersonal comparability of utility in order to connect personal marginal utility to aggregate demand. Dupuit, however, did not draw a supply curve and thus did not get price-determination into his story.

Dupuit went on to define "relative utility" as the area under the demand/marginal utility curve above the price and used it as a measure of the welfare effects of different prices -- concluding that public welfare is maximized when the price (or bridge toll) is zero. This was later known as Marshall's "consumer surplus". Alfred Marshall Alfred Marshall (July 26, 1842–July 13, 1924), born in Bermondsey, London, England, became one of the most influential economists of his time. ... This page deals with the various forms of economic surplus, including producer, consumer, government, and social/total surplus. ...

Dupuit's reputation as an economist does not rest on his advocacy of laissez-faire economics (he wrote "Commercial Freedom" in 1861) but on frequent contributions to periodicals. Wanting to evaluate the net economic benefit of public services, Dupuit analysed capacities for economic development, and attempted to construct framework for utility theory and measuring the prosperity derived with public works. He also wrote on monopoly and price discrimination. Laissez-faire is short for laissez faire, laissez passer, a French phrase meaning to let things alone, let them pass. First used by the eighteenth century Physiocrats as an injunction against government interference with trade, it is now used as a synonym for strict free market economics. ... In economics, marginal utility is the additional utility (satisfaction or benefit) that a consumer derives from an additional unit of a commodity or service. ... In economics, a monopoly (from the Greek monos, one + polein, to sell) is defined as a persistent market situation where there is only one provider of a kind of product or service. ... Price discrimination exists when sales of identical goods or services are transacted at different prices from the same provider. ...

External links

• Biography of Jules Dupuit