Eugenics Laboratory Lectures number 5: Pearson, Karl. 1909. The Problem of Practical Eugenics (London: Dulau and Co.). 38 pp. Based on a course of lectures given in May 1909. Reprinted 1910. Second edition is 1912.
Summary
Delivered by Karl Pearson, F.R.S., in May 1909, this lecture synthesizes the findings of the Eugenics course and outlines the necessary direction for practical eugenic action. Pearson argues that the fundamental laws of heredity, established through biometric studies (parent-offspring resemblance ranging from 0.4 to 0.5), demonstrate the overwhelming importance of Nature.
He asserts that the pivot for all practical eugenic action must be the creation of a selective birthrate. He critiques two major forms of philanthropic effort: factory legislation and modern charity, claiming they are the “sources of our gravest present difficulties” because they attempt to improve racial fitness by relying solely on environmental reforms while disregarding parentage and biological laws.
Pearson presents striking statistical evidence of the rapidly falling birthrate in Britain, noting that the average family size in manufacturing towns had fallen from six to seven births to three to four births. Simultaneously, he shows that the birthrate in degenerate and pathological stocks (insane, criminal, deaf-mute) has been maintained at the old, high rate, averaging approximately 6.8 children per family. This differential fertility results in the nation progressively breeding from its less capable stocks, risking national decline.
The lecture concludes by emphasizing that the eugenist must work to educate the public conscience about these biological truths, acknowledging that this message is difficult because “truth at first is often an unpalatable medicine”.
Changes Across Editions:
The Problem of Practical Eugenics was originally issued in 1909 and published in a Second Edition in 1912. The core conclusions and the data used (such as the comparison of fertility in intellectual versus pathological stocks) remain consistent. The reissuance in 1912 served primarily to update the context of the statistical investigation. Pearson notes in the updated version that the first section of his intended full statistical treatment of the changing birthrate across the country was “now ready for press”. This statement indicates the ongoing consolidation of the massive body of data underpinning the claims made in the lecture. The Second Edition reinforced the message delivered in the 1909 lecture, emphasizing the urgency of applying scientific principles to societal problems to prevent national decline, especially in light of the ongoing suspension of natural selection.
Eugenics Laboratory Lectures number 5
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