In the first half of the 19th century two main ethnological views dominated the debate about racial differences. Influenced by the New Testament, the monogenesis view asserted that all human beings were of one blood and the observed differences displayed by the various racial groups were due to their exposure to distinct climatic and environmental conditions. With a wider acceptance by French scientists and intellectuals, the polygenesis view proclaimed that different races were due to separately created species with different aptitudes and unalterable capacities. In fact, the polygenetic theory dominated French anthropology … and the proceedings of the Ethnological Society of Paris for 1841-1847 contain extreme racist statements that aroused little dissent.
Aligned with the polygenetic discourse was the Swiss physician and naturalist Louis Agassiz, who believed that blacks were a separate and inferior species rather than just individuals who were part of a less developed culture. His academic credentials and prestige lead him to the United States and become a professor at Harvard University. In 1850 he expressed his views on racial differences in the paper entitled “The Diversity of Origin of the Human Races”, where he affirmed that scientists had “the obligation to settle the relative rank among … races,” because it would be “mock-philanthropy and mock-philosophy to assume that all races have the same abilities … and that in consequence …they are entitled to the same position in human society.” 
Another voice to join the chorus of the defenders of polygenesis was the French novelist and diplomat Arthur de Gobineau, who in 1855 wrote the essay “Essai sur l’inégalité des races humaines”, translated into English in 1915 as “The Inequality of Races.” In this work Gobineau gave his scientific justification for the superiority of the white race and explained why the lower races could never achieve higher levels of civilization. Gobineau’s views had many supporters including the German composer Richard Wagner, who, in 1881, founded the Gobineau Society to disseminate this ideology to the world .
The above discussion illustrates very clearly the scientific views that shaped the understanding of the observed differences among various human races in the mid 19th century. In France, particularly, the superiority of the Europeans (or the white race) was an undeniable fact endorsed by the scientific community, consequently being the framework in which Kardec wrote his considerations in the mentioned texts  and . However, an important distinction must be made. The scientific racism practiced in the 19th century, recognized today as an attempt to make nature herself an accomplice of political inequality , was used to justify and defend slavery and later became the basis for the oppression and atrocities committed in the 20th century in the name of ethnic purity and racial intolerance. On the other hand, without conflicting with the current scientific knowledge, Allan Kardec offered a plausible explanation where reincarnation was the mechanism that restored the concept of equality and brotherhood among individuals of different races. The next section discusses this point further. Continue Reading—>