James H. Leuba (1867-1946) was a native of Switzerland who emigrated to the United States. From 1898 until 1933 he was a Professor of Psychology at Bryn Mawr College in Pennsylvania.
An admirer of William James, he became one of the founders of the academic study of the psychology of religion. An atheist, he believed that religious phenomenon could be studied as physiological events, and spent a great deal of time making a connection between drug use and religious mysticism.
He generally attempted to show in his research that the more educated a person was, the less they were inclined to believe in God.
Leuba figures prominently in two major controversies, both resulting from his famous 1916 study The Belief in God and Immortality.
One conclusion of this work was that college students were less likely to believe in God after leaving college than upon beginning college. William Jennings Bryant apparently read this study, and became so incensed by the "indoctrination" students were receiving from atheist professors he began looking for an opportunity to defend the faith in an educational setting. He was prepared, therefore, when he was called to prosecute the Scopes "monkey trial" in 1925 held in Dayton, Tennessee.
Of more immediate relevance to my book, Letter to an Atheist, is Leuba's survey of American scientists. Using the 5,500 names in the publication American Men of Science (apparently Leuba could not find any American Women of Science in 1914 when the survey was conducted), Leuba sent surveys to 1,000 randomly selected members. He received 750 responses. The results showed that 41.8% of the responding scientists believed in God. Such a response rate suggests a 95% confidence level that the results are correct, plus or minus 4 per cent.
Leuba tried to break down these results even further, separating the scientists into two different groupings: (1) physical scientists and biological scientists and (2) greater and lesser scientists by subjective estimates of the quality of their work.
Leuba claimed that biological scientists showed less belief in God than physical scientists.
He also claimed that "Greater" scientists showed less belief in God than "Lesser" scientists.
A closer look at his methodology suggests that his sample sizes for these different groupings were probably not large enough to make any conclusions with a high degree of confidence.
His sample size for physical scientists was 450, and biological scientists 300.
His sample size for "Lesser" scientists was 450, and "Greater" scientists was 300.
Leuba further complicated his findings by breaking up his study into two divisions of 500 each, each of which received approximately 375 responses. Division 1, for instance, consisted of 375 responses -- 150 from "Greater" Scientists and 225 from "Lesser" scientists. By area of functional expertise, Division 1 broke down approximately as follows: 202 physical scientists, 150 biological scientists, and 23 psychologists, philosophers, and sociologists. Leuba acknowledged that it was an error to include psychologists, philosophers, and sociologists in Division 1, and they were excluded from Division 2. In the same survey, psychologists had significantly lower rates of belief in God, but Leuba did not remove their contaminating influence from the results of Division 1.
The results of his study have been misreported as a consequence.
For instance, Nature Magazine reported in 1998 that Leuba concluded in his 1916 study that only 27% of the "Greater" scientists were believers. This is not accurate.
27% of the respondents to Division 1 reported a belief in God.
35% of the respondents to Division 2 reported a belief in God.
Nature Magazine failed to account for the inherent corruption of the Division 1 sample by psychologists, nor did it address the sample size problem.
The "margin of error" for a sample size of 150 is approximately 9 per cent.
Even if we were to accept the subjective breakdown of "greater" and "lesser" scientists that Leuba performed, the supposed difference between "greater" scientists and the population of scientists as a whole lies within the margin of error, and therefore, cannot be claimed.
One final comment on Leuba.
Though it is of no relevance to this argument, it turns out that he is remembered fondly by one of his students. The actress Katharine Hepburn (Bryn Mawr Class of 1928) recalls Professor Leuba in her memoirs for his kind and avuncular advice to her.