Editing The Mismeasure of Man (section)

===Craniometry===
[[Image:Morton drawing.png|thumb|right|250px|The "species" of man: "a Negro head . . . a Caucasian skull . . . a Mongol head", by S. G. Morton (1839)]]
''The Mismeasure of Man'' is a critical analysis of the early works of [[scientific racism]] which promoted "the theory of
unitary, innate, linearly rankable [[Intelligence#Human intelligence|intelligence]]"—such as [[craniometry]], the measurement of skull volume and its relation to [[Intellectualism|intellectual]] faculties. Gould alleged that much of the research was based largely on [[Racism|racial]] and social prejudices of the researchers rather than their scientific objectivity; that on occasion, researchers such as [[Samuel George Morton]] (1799–1851), [[Louis Agassiz]] (1807–1873), and [[Paul Broca]] (1824–1880), committed the [[Methodology|methodological]] fallacy of allowing their personal ''[[A priori knowledge|a priori]]'' expectations to influence their conclusions and analytical reasoning. Gould noted that when Morton switched from using bird seed, which was less reliable, to [[Shot (pellet)|lead shot]] to obtain endocranial-volume data, the average skull volumes changed; however, these changes were not uniform across Morton's "racial" groupings. To Gould, it appeared that unconscious [[List of cognitive biases|bias]] influenced Morton's initial results.<ref name="Kaplan et al">{{cite journal | last1 = Kaplan | first1 = Jonathan Michael | last2 = Pigliucci | first2 = Massimo | last3 = Banta | first3 = Joshua Alexander | year = 2015 | title = Gould on Morton, Redux: What can the debate reveal about the limits of data? | url = http://philpapers.org/archive/KAPGOM.pdf | journal = Studies in History and Philosophy of Biological and Biomedical Sciences | volume = 30 | pages = 1–10 }}</ref> Gould speculated,

<Blockquote>Plausible scenarios are easy to construct. Morton, measuring by seed, picks up a threateningly large black skull, fills it lightly and gives it a few desultory shakes. Next, he takes a distressingly small Caucasian skull, shakes hard, and pushes mightily at the foramen magnum with his thumb. It is easily done, without conscious motivation; expectation is a powerful guide to action.<ref>Gould, SJ (1981). ''Mismeasure of Man''. New York: Norton & Company, p. 97.</ref></Blockquote>

In 1977 Gould conducted his own analysis on some of Morton's endocranial-volume data, and alleged that the original results were based on ''a priori''  convictions and a selective use of data. He argued that when biases are accounted for, the original hypothesis—an ascending order of skull volume ranging from Blacks to Mongols to Whites—is unsupported by the data.