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Karl Pearson (1857-1936), Biographical Notes


1857 Born as the second son of a middle-class lawyer (Quaker) in London. He was educated in London, but at the age of 16, he was withdrawn (because of ill-health) from the school and sent to Hitchin; there he learned mathematics with a private tutor, Edward John Rauth.

1875 Entered King's College, Cambridge; studied mainly mathematics. He refused to attend the required divinity lectures and chapel.

1879 After graduation, he went to Germany (Berlin and Heidelberg), and studied various things: law, philosophy, mathematics, physics, evolutionary theory, literature, etc. He also learned socialism and was influenced by that.

1880 On his return to England he began preparation for the bar. He changed his name from "Carl" to "Karl". Kevles's appraisal of Pearson's socialistic view is quite interesting:

Having abandoned religion, he sought a secular creed, and he found one appropriate to his personality in a socialism---iron-handed, if necessary---based on the Fichtian imperative of subordinating the mass of citizens to the welfare of the nation-state. Pearson came to equate morality with the advancement of social evolution, the outcome of the Darwinian struggle with the ascendancy of the fittest nation, and the achievement of fitness with a nationalist socialism. (Kevles 1985, 23)

Pearson called for something akin to socialist meritocracy, declaring in 1881 that "power intellectual shall determine whether the life-calling of a man is to scavenge the streets or to guide the nation." (Kevles 1985, 24)

1884 Professor of mathematics, University College, London.

1885 Founded the Men and Women Club

1888 The Ethic of Freethought

1890 Married to Maria Sharpe (a member of the Men and Women Club); his interests shifted to biology, and Galton's Natural Inheritance (1889) stimulated his interests further.

1892 The Grammar of Science; Pearson began collaboration with Walter F.R. Weldon, Professor of Zoology, University College (they got acquinted with each other through a reform movement in London University). Weldon was also under the influence of Galton, as regards statitical treatment of biological data.

Weldon measured certain physical characteristics of several large samples of the common wild shrimp. ... Weldon found that for each sample group the size of a given organ was distributed normally about a mean---it was the first demonstration that a wild population displayed the normal distribution---but that the probable error in organ size varied from one sample to another. Weldon also applied Galton's method of statistical correlation to a pair of each shrimp's physical features--the lengths of the carapace and of the post-spinous bodily portion. He found that the degree of correlation was high and was approximately equal---the correlation coefficient came to about 0.8 out of a possible 1.0---for all the samples under study. (Kevles 1985, 27)

Figure in Weldon's 1890 paper

The shrimp has the biological name Crangon Vulgaris, and looks like the top figure, left.

Weldon measured the length of the rightmost part, for 1000 females, and the data were plotted on the bottom graph (ragged line); a smooth normal curve nicely fits the data.


Pearson and Weldon, by their collaboration, established a new discipline "biometry". Pearson (but not Weldon) shared eugenic idea with Galton, and the two became closer. But, again, Kevles characterizes Pearson's eugenics as follows:

The eugenics of Karl Pearson, husband and father, was charged less with psychosexual energy than with his committment to social imperialism---the ideological system where, in fact, his eugenic convictions had originated.

In Pearson's view, the imperial nation required more than an aconomic framework designed to give its citizens a material stake in its power; it als demanded the "high pitch of internal efficiency" won by "insuring that its numbers are substantially recruited from the better stocks." Like Francis Galton, Pearson ... equated fitness with physique and mental ability, and assumed that it was centered in the middle, and particularly the professional class. Unlike Galton, he declared that fitness extended down to the "better" sort of English workingman marked by "a clean body, a sound if slow mind, a vigorous and healthy stock, and a numerous progeny." (Kevles 1985, 32-3)

1894 The first paper of the "Mathematical Contributions to the Theory of Evolution" (18 papers, until 1916); his contributions to mathematical statistics are great. For instance, he invented the term "standard deviation"; he has shown that normal distributions are only a special case of statistical distributions which can be obtained from a single differential equation; and the chi-square test of statistical significance is also important.

1895 Pearson began offering courses in statistics at University College.

1902 Pearson, Weldon, and Galton founded the journal Biometrika; Mendelian genetics rediscovered, and a long quarrel arised between this school and the school of Biometrika.

1906 Weldon died.

1907 Eugenics Education Society was founded; but Pearson refused to join.

But Pearson steadfastly refused to join the Eugenics Education Society, to participate in political activity, or to make available his institutional resources and expertise for the support of legislative measures. (Kevles 1985, 104)

1911 On Galton's death, a large fund is given to University College. Pearson was nominated to Galton Eugenics Professorship; he was also made head of a new Department of Applied Statistics which included Galton Laboratorty of National Eugenics.

1912 Began the publication of monographs The Treasury of Human Inheritance

1914 Contact with R. A. Fisher (photo: right) began; later (beginning 1919) Pearson had a vehement quarrel with him until Pearson's death.

1925 Annales of Eugenics founded.

1933 Pearson retired. R. A. Fisher succeeded Eugenics Professorship, and Applied Statistics were maintained by Egon S. Pearson (son of Karl) and J. Neyman; the two groups were antagonistic forever.

1936 Karl Pearson died in April.


Kevles 1985

Stigler 1986

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"Karl Pearson" (MacTutor History of Mathematics Archive, St. Andrews University),

"Ronald Fisher" (MacTutor History of Mathematics Archive, St. Andrews University),

Last modified December 9, 1999. (c) Soshichi Uchii