The Mismeasure of Man is primarily concerned with discrediting 19th- and 20th-century theories that posited intelligence to be a biologically-determined, hereditary, and measurable quantity. Gould traces the history of these theories by presenting the stories and beliefs of the men behind the science. While there is no way to trace where a belief begins and another ends, the consequences of these beliefs can be determined. Moreover, as the scientific findings of hereditary intelligence are absorbed by popular culture, society is afforded new justifications for racist, sexist, and classist attitudes towards marginalized groups.

Since the scientific “truth” of hereditary intelligence upholds the superiority of white men over all other groups, a more granular ranking of marginalized groups must also exist. While the discovery of this ranking order is an unconsciously-enacted smokescreen, it still gives form to the informal, socially-constructed hierarchies that preexisted in 19th- and 20th-century Western societies. 

As men enacting unconscious social prejudices, the scientists presented in The Mismeasure of Man rely on their professional objectivity. Their collected research reveals the “truths” regarding heritable intelligence and group hierarchies. To this end, scientific evidence is used to verify, validate, and vindicate the existing social order. As such, existing social hierarchies (whites on top, blacks on the bottom) merely reflect reality, and the appeals for equality or a mixing of races are the opinions of overly-emotional hysterics, who do not possess the reason to see the underlying, logical “truth.