Quetelet's "average man": how did statistics begin to measure society in the 19th century?

Astronomers observing the stars knew that when they measured the same point many times, a slightly different number came out each time, and they took the average. The Belgian astronomer and mathematician Adolphe Quetelet asked: don't people's height, weight and even behaviour cluster around such an "average" too?

• The 1835 book. Quetelet's most influential work, "Sur l'homme et le développement de ses facultés, ou Essai de physique sociale" (On Man and the Development of His Faculties, or an Essay on Social Physics), came out in 1835.
• The "average man" (l'homme moyen). In the book Quetelet proposed the concept of the "average man" to describe society as a whole: he showed that human characteristics cluster around a central value.
• "Social physics". Quetelet believed that society, like nature, can be studied through laws. That is why he called his work "social physics".
• It sparked debate. Many of the objections to the book concerned the idea of the "average man": if the number of crimes is stable from year to year, is human behaviour predetermined, and where does free will come in?
• An international congress. In 1853 Quetelet chaired the first International Statistical Congress in Brussels. Afterwards such congresses were held in other cities as well, and agreements were reached so that countries' data could be compared.
• From manual labour to the machine. In the 19th century tables were drawn by hand and numbers were counted on paper. In the USA processing the 1880 census by hand dragged on for years: the sources put it at about seven to eight years. That is why, for the 1890 census, Herman Hollerith proposed an electrical tabulating machine that worked with punched cards: a hole in the card closed an electrical circuit and the counter went up by one.
• Statistics became a matter of state. In the 19th century figures began to be collected not only for the ruler but also to understand society: births, deaths, crime, health. Quetelet was one of the scholars who urged that this data should speak a common language.

Example (prepared by the author, hypothetical figures). The heights of 5 pupils in year 7 at the "Tong" school were measured: 148, 152, 150, 155, 145 cm. The average: (148 + 152 + 150 + 155 + 145) ÷ 5 = 150 cm. This "average pupil" may not actually exist in the class, but it says a lot about the class in a single number: for example, when choosing the height of the desks. Quetelet's idea worked in the same way, and its danger lies here too: an average figure does not describe any particular person.