Blue Plaques

PEARSON, Karl (1857-1936)

Plaque erected in 1983 by Greater London Council at 7 Well Road, Hampstead, London, NW3 1LH, London Borough of Camden

All images © English Heritage

Profession

Statistician

Category

Economics and Statistics

Inscription

KARL PEARSON 1857-1936 Pioneer Statistician lived here

Material

Ceramic

Notes

Put up by the Greater London Council in 1983

Karl Pearson is credited with establishing the field of modern statistics, which emerged from his work in mathematical biology or biometry. In connection with this, he was also an early proponent of eugenics – the selective breeding of people to ‘improve’ a population – which now makes him extremely controversial.

A photograph of Karl Pearson in 1910
A photograph of Karl Pearson in 1910 © National Portrait Gallery, London

Early life and education

Carl Pearson was born to nonconformist parents in Islington and won a scholarship to study mathematics at King’s College, Cambridge. He was awarded a fellowship that allowed him to travel to Heidelberg and Berlin, where he studied mathematics, physics and philosophy. By this time Pearson had become influenced by Darwinism and was a freethinker and agnostic. 

While in Germany, Pearson converted to a form of socialism. He would return frequently to the country, where he felt freed from the constraints of the British class system, and by 1890 had adopted Karl as the spelling of his given name. On returning to London in 1880 Pearson followed his father into the legal profession. But he practiced for only a short time before resuming his mathematical work. 

Mathematics and statistics

In 1884 Pearson was appointed Goldsmid Professor of Applied Mathematics and Mechanics at University College, London (UCL), to teach maths to engineers. His appointment as Professor of Geometry at Gresham College in 1890 allowed him to continue to give free evening lectures on statistics to artisans, clerks and others who worked in the City of London. The first lectures formed the basis of his internationally influential book The Grammar of Science (1892), and the remaining 30 provided a framework for his innovations in statistics. The last dozen of these incorporated Charles Darwin’s ideas of variation, speciation and natural selection. 

The inheritance of physical and mental characteristics, and the relative fertility of the fit and unfit, now formed the basis for Pearson’s social-Darwinistic ‘eugenic creed’. 

Biometrics

In 1894 Pearson began teaching statistics at UCL’s Biometric Laboratory, which he had started in order to measure allegedly inherited characteristics in mathematical terms.

In the Victorian period the application of statistics was closely associated with public health and the social sciences. Pearson proposed that it also belonged to zoology, evolutionary biology and astronomy – and thus to mathematics. In the 1890s, Pearson and his UCL colleague the evolutionary biologist Walter FR Weldon began to look for empirical evidence of natural selection. In this they were inspired by the theories of Charles Darwin and the methods of Darwin’s cousin, the statistician Francis Galton. Both had read Galton’s Natural Inheritance (1889), which explored how traits and talents are inherited and which laid the foundations for modern statistics. Very soon Pearson and Galton formed a close personal bond. 

Karl Pearson (left) alongside Francis Galton in about 1905
Karl Pearson (left) alongside Francis Galton in about 1905 © adoc-photos/Corbis via Getty Images

Like Galton, Pearson was fascinated with heredity and statistics and, working with Weldon’s questions and data, was able to develop schemes through which to manage large sets of data and provide tools to calculate variability. In 1901, after the Royal Society resolved that mathematics and biology should not be mixed, the journal Biometrika was founded to promote the study of biometrics, with Galton as a consultant and Pearson and Weldon as its editors. Pearson went on to edit the journal for 35 years.

Pearson was one of the founders of biometry and the use of statistics in many branches of science, and is remembered for the Pearson Significance Test. His work led to the professionalisation of statistics and in 1917 to the first British degree course in the subject. 

Professor of national eugenics

In 1907, when Galton – who had coined the term ‘eugenics’ – stepped down as Director of the Eugenics Record Office which he had helped to found at UCL, Pearson accepted his request to take over. He renamed it the Galton Laboratory for National Eugenics.  

On Galton’s death in 1911, Pearson became the first Galton Professor of Eugenics at UCL. This post allowed him to focus on mathematical statistics, biometry and eugenics until he retired in 1933.

Karl Pearson was elected a Fellow of the Royal Society in 1896 for his contributions to statistics and evolutionary theory and awarded the society’s Darwin medal in 1898. As a socialist, he refused the offer of an OBE in 1920, and also a knighthood in 1935. He died unexpectedly at his Surrey cottage in 1936.

National eugenics and its legacy

National Eugenics was, as Galton Eugenic Laboratory publications explained, ‘the study of agencies under social control, that may improve or impair the racial qualities of future generations, either physically or mentally’. As Pearson’s own publications make clear, this was based on racist ‘science’ which called for the creation ‘of a homogeneous white race, whose fertility shall markedly dominate that of the black’. He held similar views on ‘the fertility of the unthrifty, of the mentally defective’ and ‘the criminal, the tramp and the congenital pauper’, insisting that the right to live did not convey the right to reproduce. 

In a published speech at his retirement dinner in 1934, Pearson suggested that the culmination of eugenics lay ‘in the future, perhaps with Reichskanzler Hitler and his proposals to regenerate the German people. In Germany a vast experiment is at hand, and some of you may live to see its results’. Later that year, however, he wrote privately that he found the Nazis intolerable.

The ‘results’ Pearson spoke of turned out to be the Nazi regime’s atrocities in the name of racial purity, which discredited eugenics. But even before the Second World War, advances in the understanding of human genetics had begun to undermine the scientific credibility of eugenics. In 2020, following an inquiry into UCL’s historical links with the eugenics movement, the names of Galton and Pearson were removed from two lecture theatres and a building at the university.

Blue plaque

Pearson is commemorated in a plaque at 7 Well Road, Hampstead, erected by the Greater London Council in 1983. He moved to the house – one of a procession of semi-detached red-brick pairs built in about 1880 – with his growing family in 1892. The house was the birthplace of Pearson’s son, Egon (1895−1980), also an eminent statistician, and remained his London home until the end of his life.

Further reading

Bricks + Mortals: a history of eugenics told through buildings (UCL podcast) 

LA Farrall, The Origins and Growth of the English Eugenics Movement, 1865–1925 (London, 1969; new edn, 2019)  

BW Hart, ‘Watching the “eugenic experiment” unfold: the mixed views of British eugenicists toward Nazi Germany in the early 1930s’, Journal of the History of Biology, 45:1 (2012), 33–63

ME Magnello, ‘Karl Pearson and the establishment of mathematical statistics’, International Statistical Review, 77:1 (2009), 3–29 (subscription required)

TM Porter, Karl Pearson: The Scientific Life in a Statistical Age (Princeton, NJ, 2010)

B Semmel, ‘Karl Pearson: Socialist and Darwinist’, The British Journal of Sociology, 9:2 (1958), 111–25

J Woiak, ‘Karl Pearson (1857–1936)’, Oxford Dictionary of National Biography (Oxford, 2004; subscription required) 

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