Pearson was offered a Germanics post at King's College, Cambridge. Comparing Cambridge students to those he knew from Germany, Karl found German students inathletic and weak. He wrote his mother, "I used to think athletics and sport was overestimated at Cambridge, but now I think it cannot be too highly valued."
On returning to England in 1880, Pearson first went to Cambridge:
Back in Cambridge, I worked in the engineering shops, but drew up the schedule in Mittel- and Althochdeutsch for the Medieval Languages Tripos.
In his first book, The New Werther, Pearson gives a clear indication of why he studied so many diverse subjects:
I rush from science to philosophy, and from philosophy to our old friends the poets; and then, over-wearied by too much idealism, I fancy I become practical in returning to science. Have you ever attempted to conceive all there is in the world worth knowing—that not one subject in the universe is unworthy of study? The giants of literature, the mysteries of many-dimensional space, the attempts of Boltzmann and Crookes to penetrate Nature's very laboratory, the Kantian theory of the universe, and the latest discoveries in embryology, with their wonderful tales of the development of life—what an immensity beyond our grasp! [...] Mankind seems on the verge of a new and glorious discovery. What Newton did to simplify the planetary motions must now be done to unite in one whole the various isolated theories of mathematical physics.
Pearson then returned to London to study law, emulating his father. Quoting Pearson's own account:
Coming to London, I read in chambers in Lincoln's Inn, drew up bills of sale, and was called to the Bar, but varied legal studies by lecturing on heat at Barnes, on Martin Luther at Hampstead, and on Lassalle and Marx on Sundays at revolutionary clubs around Soho.
After Galton's death in 1911, Pearson embarked on producing his definitive biography — a three-volume tome of narrative, letters, genealogies, commentaries, and photographs — published in 1914, 1924, and 1930, with much of Pearson's own money paying for their print runs. The biography, done "to satisfy myself and without regard to traditional standards, to the needs of publishers or to the tastes of the reading public", triumphed Galton's life, work and personal heredity. He predicted that Galton, rather than Charles Darwin, would be remembered as the most prodigious grandson of Erasmus Darwin.
When Galton died, he left the residue of his estate to the University of London for a Chair in Eugenics. Pearson was the first holder of this chair — the Galton Chair of Eugenics, later the Galton Chair of Genetics—in accordance with Galton's wishes. He formed the Department of Applied Statistics (with financial support from the Drapers' Company), into which he incorporated the Biometric and Galton laboratories. He remained with the department until his retirement in 1933, and continued to work until his death at Coldharbour, Surrey on 27 April 1936.
Pearson was a "zealous" atheist and a freethinker.
In 1890 Pearson married Maria Sharpe. The couple had three children: Sigrid Loetitia Pearson, Helga Sharpe Pearson, and Egon Pearson, who became a statistician himself and succeeded his father as head of the Applied Statistics Department at University College. Maria died in 1928 and in 1929 Karl married Margaret Victoria Child, a co-worker at the Biometric Laboratory. He and his family lived at 7 Well Road in Hampstead, now marked with a blue plaque.
Einstein and Pearson's work
When the 23-year-old Albert Einstein started the Olympia Academy study group in 1902, with his two younger friends, Maurice Solovine and Conrad Habicht, his first reading suggestion was Pearson's The Grammar of Science. This book covered several themes that were later to become part of the theories of Einstein and other scientists. Pearson asserted that the laws of nature are relative to the perceptive ability of the observer. Irreversibility of natural processes, he claimed, is a purely relative conception. An observer who travels at the exact velocity of light would see an eternal now, or an absence of motion. He speculated that an observer who travelled faster than light would see time reversal, similar to a cinema film being run backwards. Pearson also discussed antimatter, the fourth dimension, and wrinkles in time.
Pearson's relativity was based on idealism, in the sense of ideas or pictures in a mind. "There are many signs," he wrote, "that a sound idealism is surely replacing, as a basis for natural philosophy, the crude materialism of the older physicists." (Preface to 2nd Ed., The Grammar of Science) Further, he stated, "...science is in reality a classification and analysis of the contents of the mind..." "In truth, the field of science is much more consciousness than an external world." (Ibid., Ch. II, § 6) "Law in the scientific sense is thus essentially a product of the human mind and has no meaning apart from man." (Ibid., Ch. III, § 4)
Politics and eugenics
Karl Pearson at work, 1910.
A eugenicist who applied his social Darwinism to entire nations, Pearson saw war against "inferior races" as a logical implication of the theory of evolution. "My view – and I think it may be called the scientific view of a nation," he wrote, "is that of an organized whole, kept up to a high pitch of internal efficiency by insuring that its numbers are substantially recruited from the better stocks, and kept up to a high pitch of external efficiency by contest, chiefly by way of war with inferior races." He reasoned that, if August Weismann's theory of germ plasm is correct, the nation is wasting money when it tries to improve people who come from poor stock.
Weismann claimed that acquired characteristics could not be inherited. Therefore, training benefits only the trained generation. Their children will not exhibit the learned improvements and, in turn, will need to be improved. "No degenerate and feeble stock will ever be converted into healthy and sound stock by the accumulated effects of education, good laws, and sanitary surroundings. Such means may render the individual members of a stock passable if not strong members of society, but the same process will have to be gone through again and again with their offspring, and this in ever-widening circles, if the stock, owing to the conditions in which society has placed it, is able to increase its numbers."
"History shows me one way, and one way only, in which a high state of civilization has been produced, namely, the struggle of race with race, and the survival of the physically and mentally fitter race. If you want to know whether the lower races of man can evolve a higher type, I fear the only course is to leave them to fight it out among themselves, and even then the struggle for existence between individual and individual, between tribe and tribe, may not be supported by that physical selection due to a particular climate on which probably so much of the Aryan's success depended."
In The Myth of the Jewish Race Raphael and Jennifer Patai cite Karl Pearson's 1925 opposition (in the first issue of the journal Annals of Eugenics which he founded) to Jewish immigration into Britain. Pearson alleged that these immigrants "will develop into a parasitic race. [...] Taken on the average, and regarding both sexes, this alien Jewish population is somewhat inferior physically and mentally to the native population".
Contributions to biometrics
Karl Pearson was important in the founding of the school of biometrics, which was a competing theory to describe evolution and population inheritance at the turn of the 20th century. His series of eighteen papers, "Mathematical Contributions to the Theory of Evolution" established him as the founder of the biometrical school for inheritance. In fact, Pearson devoted much time during 1893 to 1904 to developing statistical techniques for biometry. These techniques, which are widely used today for statistical analysis, include the chi-squared test, standard deviation, and correlation and regression coefficients. Pearson's Law of Ancestral Heredity stated that germ plasm consisted of heritable elements inherited from the parents as well as from more distant ancestors, the proportion of which varied for different traits. Karl Pearson was a follower of Galton, and although the two differed in some respects, Pearson used a substantial amount of Francis Galton's statistical concepts in his formulation of the biometrical school for inheritance, such as the law of regression. The biometric school, unlike the Mendelians, focused not on providing a mechanism for inheritance, but rather on providing a mathematical description for inheritance that was not causal in nature. While Galton proposed a discontinuous theory of evolution, in which species would have to change via large jumps rather than small changes that built up over time, Pearson pointed out flaws in Galton's argument and actually used Galton's ideas to further a continuous theory of evolution, whereas the Mendelians favored a discontinuous theory of evolution. While Galton focused primarily on the application of statistical methods to the study of heredity, Pearson and his colleague Weldon expanded statistical reasoning to the fields of inheritance, variation, correlation, and natural and sexual selection.
For Pearson, the theory of evolution was not intended to identify a biological mechanism that explained patterns of inheritance, whereas Mendelian's theory postulated the gene as the mechanism for inheritance. Pearson criticized Bateson and other biologists for their failure to adopt biometrical techniques in their study of evolution. Pearson criticized biologists who did not focus on the statistical validity of their theories, stating that "before we can accept [any cause of a progressive change] as a factor we must have not only shown its plausibility but if possible have demonstrated its quantitative ability" Biologists had succumb to "almost metaphysical speculation as to the causes of heredity," which had replaced the process of experimental data collection that actually might allow scientists to narrow down potential theories.
For Pearson, laws of nature were useful for making accurate predictions and for concisely describing trends in observed data. Causation was the experience "that a certain sequence has occurred and recurred in the past". Thus, identifying a particular mechanism of genetics was not a worthy pursuit of biologists, who should instead focus on mathematical descriptions of empirical data. This, in part led to the fierce debate between the biometricians and the Mendelians, including Bateson. After Bateson rejected one of Pearson's manuscripts that described a new theory for the variability of an offspring, or homotyposis, Pearson and Weldon established Biometrika in 1902. Although the biometric approach to inheritance eventually lost to the Mendelian approach, the techniques Pearson and the biometricians at the time developed are vital to studies of biology and evolution today.
Awards from professional bodies
Pearson achieved widespread recognition across a range of disciplines and his membership of, and awards from, various professional bodies reflects this:
He was also elected an Honorary Fellow of King's College, Cambridge, the Royal Society of Edinburgh, University College, London and the Royal Society of Medicine, and a Member of the Actuaries' Club. A sesquicentenary conference was held in London on 23 March 2007, to celebrate the 150th anniversary of his birth.
Contributions to statistics
Pearson's work was all-embracing in the wide application and development of mathematical statistics, and encompassed the fields of biology, epidemiology, anthropometry, medicine, psychology and social history. In 1901, with Weldon and Galton, he founded the journal Biometrika whose object was the development of statistical theory. He edited this journal until his death. Among those who assisted Pearson in his research were a number of female mathematicians who included Beatrice Mabel Cave-Browne-Cave and Frances Cave-Browne-Cave. He also founded the journal Annals of Eugenics (now Annals of Human Genetics) in 1925. He published the Drapers' Company Research Memoirs largely to provide a record of the output of the Department of Applied Statistics not published elsewhere.
Pearson's thinking underpins many of the 'classical' statistical methods which are in common use today. Examples of his contributions are:
Pearson's system of continuous curves. A system of continuous univariate probability distributions that came to form the basis of the now conventional continuous probability distributions. Since the system is complete up to the fourth moment, it is a powerful complement to the Pearsonian method of moments.
Pearson, Karl (1900). "On the Criterion that a Given System of Deviations from the Probable in the Case of a Correlated System of Variables is Such that it can be Reasonably Supposed to Have Arisen from Random Sampling," Philosophical Magazine, 5th Series, Vol. L, pp. 157–175.
^Provine, William B. (2001). The Origins of Theoretical Population Genetics. University of Chicago Press, p. 29.
^Tankard, James W. (1984). The Statistical Pioneers, Schenkman Pub. Co.
^Blaney, Tom (2011). The Chief Sea Lion's Inheritance: Eugenics and the Darwins. Troubador Pub., p. 108. Also see Pearson, Roger (1991). Race, Intelligence and Bias in Academe. Scott-Townsend Publishers.
^McGrayne, Sharon Bertsch. The Theory That Would Not Die: How Bayes' Rule Cracked the Enigma Code, Hunted Down Russian Submarines, and Emerged Triumphant from Two Centuries of Controversy: Yale UP, 2011. Print. "Karl Pearson...was a zealous atheist..."
^Porter, Theodore M. Karl Pearson: The Scientific Life in a Statistical Age. Princeton: Princeton UP, 2004. Print.
^Patai, Raphael, & Jennifer Patai (1989). The Myth of the Jewish Race. Wayne State University Press, p. 146. ISBN978-0814319482
^Pearson, Karl; Moul, Margaret (1925). "The Problem of Alien Immigration into Great Britain, Illustrated by an Examination of Russian and Polish Jewish Children". Annals of Eugenics. I (2): 125–126. doi:10.1111/j.1469-1809.1925.tb02037.x.
^Farrall, Lyndsay A. (August 1975). "Controversy and Conflict in Science: A Case Study The English Biometric School and Mendel's Laws". Social Studies of Science. 5 (3): 269–301. doi:10.1177/030631277500500302. PMID11610080.
^Morrison, Margaret (1 March 2002). "Modelling Populations: Pearson and Fisher on Mendelism and Biometry". The British Journal for the Philosophy of Science. 53: 39–68. doi:10.1093/bjps/53.1.39.
^ abPearson, Karl (1892). The grammar of science. The contemporary science series. London : New York: Walter Scott ; Charles Scribner's Sons.
^Pearson, Karl (1 January 1896). "Mathematical Contributions to the Theory of Evolution. III. Regression, Heredity, and Panmixia". Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 187: 253–318. Bibcode:1896RSPTA.187..253P. doi:10.1098/rsta.1896.0007. ISSN1364-503X.
^Gillham, Nicholas (9 August 2013). "The Battle Between the Biometricians and the Mendelians: How Sir Francis Galton Caused his Disciples to Reach Conflicting Conclusions About the Hereditary Mechanism". Science & Education. 24 (1–2): 61–75. Bibcode:2015Sc&Ed..24...61G. doi:10.1007/s11191-013-9642-1.
^Mackenzie, Donald (1981). Statistics in Britain, 1865–1930: The Social Construction of Scientific Knowledge, Edinburgh University Press.
^Hald, Anders (1998). A History of Mathematical Statistics from 1750 to 1930. Wiley, p. 651.
^Analyse Mathematique. Sur Les Probabilties des Erreurs de Situation d'un Point Mem. Acad. Roy. Sei. Inst. France, Sci. Math, et Phys., t. 9, p. 255-332. 1846
^Wright, S., 1921. Correlation and causation. Journal of agricultural research, 20(7), pp.557-585
^Stigler, S. M. (1989). "Francis Galton's Account of the Invention of Correlation". Statistical Science. 4 (2): 73–79. doi:10.1214/ss/1177012580.
^ abcdPearson, K. (1900). "On the Criterion that a given System of Deviations from the Probable in the Case of a Correlated System of Variables is such that it can be reasonably supposed to have arisen from Random Sampling". Philosophical Magazine. Series 5. Vol. 50 no. 302. pp. 157–175. doi:10.1080/14786440009463897.
^Neyman, J.; Pearson, E. S. (1928). "On the use and interpretation of certain test criteria for purposes of statistical inference". Biometrika. 20 (1/2): 175–240. doi:10.2307/2331945. JSTOR2331945.
^Pearson, K. (1901). "On Lines and Planes of Closest Fit to Systems of Points is Space". Philosophical Magazine. Series 6. Vol. 2 no. 11. pp. 559–572. doi:10.1080/14786440109462720.
^Jolliffe, I. T. (2002). Principal Component Analysis, 2nd ed. New York: Springer-Verlag.
^Pearson, K. (1895). "Contributions to the Mathematical Theory of Evolution. II. Skew Variation in Homogeneous Material". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 186: 343–414. Bibcode:1895RSPTA.186..343P. doi:10.1098/rsta.1895.0010.
Most of the biographical information above is taken from the Karl Pearson page at the Department of Statistical Sciences at University College London, which has been placed in the public domain. The main source for that page was A list of the papers and correspondence of Karl Pearson (1857–1936) held in the Manuscripts Room, University College London Library, compiled by M. Merrington, B. Blundell, S. Burrough, J. Golden and J. Hogarth and published by the Publications Office, University College London, 1983.