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Lambert Adolphe Jacques Quetelet (22 February 1796 – 17 February 1874) was a Belgian astronomer, mathematician, statistician and sociologist. He founded and directed the Brussels Observatory and was influential in introducing statistical methods to the social sciences. His name is sometimes spelled with an accent as Quételet.


Adolphe was born in Ghent, Belgium, the son of François-Augustin-Jacques-Henri Quetelet, a Frenchman and Anne Françoise Vandervelde, a Belgian. His father François was born at Ham, in Picardy, and being of a somewhat adventurous spirit, crossed the English Channel and became a British citizen and the secretary of a Scottish nobleman. In this capacity he travelled with his employer on the Continent, particularly spending time in Italy. At aged about 31, he settled in Ghent and was employed by the city, where Adolphe was born the fifth of nine children, several of whom died in childhood.

Francois died when Adolphe was only seven years old. Adolphe studied at the Ghent lycée, where he started teaching mathematics in 1815 at the age of 19. In 1819 he moved to the Athenaeum in Brussels and in the same year he completed his dissertation (De quibusdam locis geometricis, necnon de curva focal – Of some new properties of the focal distance and some other curves).

Quetelet received a doctorate in mathematics in 1819 from the University of Ghent. Shortly thereafter, the young man set out to convince government officials and private donors to build an astronomical observatory in Brussels; he succeeded in 1828. He became a member of the Royal Academy in 1820. He lectured at the museum for sciences and letters and at the Belgian Military School. In 1850, he was elected a foreign member of the Royal Swedish Academy of Sciences.

Quetelet also founded several statistical journals and societies, and was especially interested in creating international cooperation among statisticians.

In 1855 Quetelet suffered from apoplexy, which diminished but did not end his scientific activity. He died in Brussels on 17 February 1874, and is buried in the Brussels Cemetery.

His scientific research encompassed a wide range of different scientific disciplines: meteorology, astronomy, mathematics, statistics, demography, sociology, criminology and history of science. He made significant contributions to scientific development, but he also wrote several monographs directed to the general public. He founded the Royal Observatory of Belgium, founded or co-founded several national and international statistical societies and scientific journals, and presided over the first series of the International Statistical Congresses. Quetelet was a liberal and an anticlerical, but not an atheist or materialist nor a socialist.
Social physics

The new science of probability and statistics was mainly used in astronomy at the time, to get a handle on measurement errors with the method of least squares. Quetelet was among the first who attempted to apply it to social science, planning what he called a "social physics". He was keenly aware of the overwhelming complexity of social phenomena, and the many variables that needed measurement. His goal was to understand the statistical laws underlying such phenomena as crime rates, marriage rates or suicide rates. He wanted to explain the values of these variables by other social factors. These ideas were rather controversial among other scientists at the time who held that it contradicted a concept of freedom of choice.

His most influential book was Sur l'homme et le développement de ses facultés, ou Essai de physique sociale, published in 1835 (In English translation, it is titled Treatise on Man, but a literal translation would be "On Man and the Development of his Faculties, or Essays on Social Physics"). In it, he outlines the project of a social physics and describes his concept of the "average man" (l'homme moyen) who is characterized by the mean values of measured variables that follow a normal distribution. He collected data about many such variables.

When Auguste Comte discovered that Quetelet had appropriated the term 'social physics', which Comte had originally introduced, Comte found it necessary to invent the term 'sociologie' (sociology) because he disagreed with Quetelet's collection of statistics.

Quetelet was an influential figure in criminology. Along with Andre-Michel Guerry, he helped to establish the cartographic school and positivist schools of criminology which made extensive use of statistical techniques. Through statistical analysis, Quetelet gained insight into the relationships between crime and other social factors. Among his findings were strong relationships between age and crime, as well as gender and crime. Other influential factors he found included climate, poverty, education, and alcohol consumption, with his research findings published in Of the Development of the Propensity to Crime.[1]

In 1835 he presented his theory of the average man in Sur l'homme et le développement de ses facultés, essai d'une physique sociale, which measurements of human trait are grouped according to the normal curve.

In terms of influence over later public health agendas, was Quetelet's establishment of a simple measure for classifying people's weight relative to an ideal weight for their height. His proposal, the body mass index (or Quetelet index), has endured with minor variations to the present day.[2] Anthropometric data is used in modern applications and referenced in the development of every consumer-based product.

1823. Relation d'un voyage fait à la grotte de Han au mois d'août 1822'. 'With M.M. Kickx.
1827. Recherches sur la population, les naissances, les décès, les prisons, les dépôts de mendicité, etc., dans le royaume des Pays-Bas.
1829. Recherches statistiques sur le royaume des Pays-Bas.
1831. The Propensity to Crime.
1834. Astronomie élémentaire.
1835. Sur l'homme et le développement de ses facultés, ou Essai de physique sociale. 2 volumes.
1838. De l'influence des saisons sur la mortalité aux différens âges dans la Belgique.
1839. Catalogue des principales apparitions d'étoiles filantes.
1842. A Treatise on Man and the Development of His Faculties.
1843. Sur l'emploi de la boussole dans les mines.
1845–1851. Sur le climat de la Belgique. 2 volumes.
1848. Du système social et des lois qui le régissent.
1848. Sur la statistique morale et les principes qui doivent en former la base.
1850. Mémoire sur les lois des naissances et de la mortalité à Bruxelles.
1853. Mémoire sur les variations périodiques et non périodiques de la température, d'après les observations faites, pendant vingt ans, à l'observatoire royal de Bruxelles.
1864. Histoire des sciences mathématiques et physiques chez les Belges.
1867. Météorologie de la Belgique comparée à celle du globe.
1867. Sciences mathématiques et physiques au commencement du XIXe siècle.
1869. Sur la physique du globe en Belgique.
1870. Anthropométrie, ou Mesure des différentes facultés de l'homme.


^ Piers Beirne (1987). "Adolphe Quetelet and the Origins of Positivist Criminology". In; American Journal of Sociology 92(5): pp. 1140–1169.
^ Garabed Eknoyan (2008). "Adolphe Quetelet (1796–1874) – the average man and indices of obesity". In: Nephrol. Dial. Transplant. 23 (1): 47–51.

Further reading

Ian Hacking (1990). The Taming of Chance. Cambridge University Press, chapters 13–15.
Alain Desrosières (1998). The Politics of Large Numbers: A History of Statistical Reasoning. Harvard University Press, chapter 3.
Stephen Stigler (1999). Statistics on the Table. Harvard University Press, chapter 2.
Philip Ball (2005). Critical Mass: How One Thing Leads to Another. Arrow Books 2005, chapter 3.
Fabien Locher (2007). "The observatory, the land-based ship and the crusades: earth sciences in european context, 1830–1850", British Journal for History of Science, 40(4), 2007, pp. 491–504 (On the leading role of Adolphe Quetelet in the fields of meteorology and geomagnetism in early nineteenth-century).

External links
Wikisource has original works written by or about:
Adolphe Quetelet

Tylor, Edward Burnett (May 1872) "Wikisource link to Quetelet on the Science of Man" Popular Science Monthly 1 D. Appleton & Company. Wikisource ISSN 0161-7370 Wikisource link [scan]
O'Connor, John J.; Robertson, Edmund F., "Adolphe Quetelet", MacTutor History of Mathematics archive, University of St Andrews.

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