Agassiz’s racial theories shaped Lincoln’s views on racial equality.

Evidence

Through these sessions, I learned that Louis Agassiz had also met with President Abraham Lincoln and that his racist theories had a profound effect on Lincoln’s point of view. This was evident in the debate he had with Stephen A. Douglas, the Illinois senator he was challenging for his seat, on September 18, 1858—just three years before Lincoln was elected president of the United States. … “I am not, nor ever have been, in favor of bringing about in any way the social and political equality of the white and black races, I am not nor ever have been in favor of making voters or jurors of negroes, nor of qualifying them to hold office, nor to intermarry with white people; and I will say in addition to this that there is a physical difference between the white and black races which I believe will forever forbid the two races living together on terms of social and political equality,” Lincoln stated. “And inasmuch as they cannot so live, while they do remain together there must be the position of superior and inferior, and I as much as any other man am in favor of having the superior position assigned to the white race.” — Tamara Lanier, From These Roots, 824

Categorization

• QUESTION: The causal claim that Agassiz directly influenced Lincoln’s 1858 debate language is the author’s inference from juxtaposition; worth checking whether historians support a direct link.