Karl Pearson: The Scientific Life in a Statistical Age

  • Theodore M. Porter
Princeton University Press: 2004. 352 pp. $35, £22.95 0691114455 | ISBN: 0-691-11445-5
Karl Pearson's statistical analysis provided early support for Darwin's theory of natural selection. Credit: SPL

Karl Pearson was one of the founders of modern statistics and a major contributor to the creation of neodarwinian evolutionary theory. He was also a strong supporter of eugenics — the policy of ‘improving’ humans by controlling their reproduction. His contributions to science and mathematics were obscured by the hostility of some of the next generation of statisticians, notably R. A. Fisher. But more recently there has been a wider recognition of the part Pearson played in the rise of a statistical approach that has transformed our vision of nature.

Theodore Porter's book on Pearson is not a biography in the conventional sense. It focuses on the early part of his career in an effort to show how he was drawn to the study of statistics and eventually conceived it as the key to a new philosophy of nature, which was to become his life's work. Those seeking extended analysis of Pearson's work on statistics, evolutionary theory and eugenics will have to look elsewhere, because these have more to do with the later part of his career, which Porter surveys in a single, penultimate chapter. It is not Porter's intention to carry on, but this could easily be the first part of a two-volume biography.

The great value of Porter's book is that this focus on the early phase of Pearson's career highlights the complex route by which his quest for emotional and intellectual satisfaction led him towards the project that would, in effect, create modern statistics. This is very much the story of a romantic hero grappling with the challenges thrown at him by life and love. He studied mathematics at King's College, Cambridge, emerging as third wrangler in the mathematics Tripos (he was placed third in the lists of those completing the examination), despite spending much of his time on other intellectual pursuits. These alternative interests led Pearson to study German culture, and he become an expert on the Reformation and passion plays. In 1884, though, he was appointed professor of applied mathematics at University College London, where he worked on the mathematical description of the behaviour of elastic bodies.

This hardly sounds the stuff of high romance, but Pearson was driven by inner passions to seek out a new vision of the truth and make his name by promoting it. In the course of his intellectual wanderings he became a socialist (although the story that he changed his name from Carl to Karl in honour of Karl Marx is apocryphal) and he took up ‘the woman question’ about women's rights. His relations with the opposite sex were mixed up in complicated ways with his intellectual and ethical interests, but his support for women's rights was genuine.

In addition to his post at University College London, Pearson was appointed to the Gresham chair of geometry in 1890 and began a three-year course of lectures to non-academic students in which his new approach to statistics was formulated. He chose statistics because by using familiar activities such as games of chance he could appeal to students who would not have appreciated a more abstract approach. For Porter, however, Pearson's 1892 book The Grammar of Science is the key statement of what was now emerging as a foundation for science itself. In 1893, the biologist W. F. R. Weldon approached Pearson for help with analysing his data on variation within populations, as a test of the darwinian theory of natural selection. The pieces of the jigsaw puzzle now fell into place, and Pearson was soon pioneering his revolution in statistical thinking.

The end results of Pearson's intellectual pilgrimage are clear enough, but specialists may have doubts about the way Porter sees the whole package eventually coming together. Porter is not over-generous with references to the secondary literature, which makes it difficult to relate his interpretations to those published by other scholars. It is not always clear just how revolutionary Pearson's new techniques were: Porter writes of him taking up mathematical statistics as though the field were already in existence, but some would argue that Pearson actually created the field in its modern form. Furthermore, Eileen Magnello has suggested (Hist. Sci. 37, 79–196, 123–150; 1999) that The Grammar of Science is not the best guide to the whole statistical project. And Weldon plays a disappointingly small role in Porter's book, considering that it was the problems generated by his data that helped Pearson complete his intellectual odyssey.

Porter's study is innovative because its focus on the complex nature of Pearson's early life provides a major counterweight to conventional studies of his later work in biology and eugenics. Whether his intellectual and emotional struggles made him the tortured outsider that Porter envisages is a moot point — most turn-of-the-century intellectuals were that way inclined, at least in Britain. But perhaps we should accept that with so complex a figure, differing interpretations are bound to emerge.