A hundred years ago, the fact that people from different racial backgrounds had very different rates of success in education, in the economy and in other endeavors, was taken as proof that some races were genetically superior to others.
Some races were considered to be so genetically inferior that eugenics was proposed to reduce their reproduction, and Francis Galton urged "the gradual extinction of an inferior race."
It was not a bunch of fringe cranks who said things like this. Many held Ph.D.s from the leading universities, taught at the leading universities and were internationally renowned.
Presidents of Stanford University and of MIT were among the many academic advocates of theories of racial inferiority -- applied mostly to people from Eastern and Southern Europe, since it was just blithely assumed in passing that blacks were inferior.
This was not a left-right issue. The leading crusaders for theories of genetic superiority and inferiority were iconic figures on the left, on both sides of the Atlantic.
John Maynard Keynes helped create the Cambridge Eugenics Society. Fabian socialist intellectuals H.G. Wells and George Bernard Shaw were among many other leftist supporters of eugenics.
It was much the same story on this side of the Atlantic. President Woodrow Wilson, like many other Progressives, was solidly behind notions of racial superiority and inferiority. He showed the movie "Birth of a Nation," glorifying the Ku Klux Klan, at the White House, and invited various dignitaries to view it with him.
Such views dominated the first two decades of the 20th century. Now fast forward to the last few decades of the 20th century. The political left of this era was now on the opposite end of the spectrum on racial issues. Yet they too regarded differences in outcomes among racial and ethnic groups as something unusual, calling for some single, sweeping explanation.
Now, instead of genes being the overriding reason for differences in outcomes, racism became the one-size-fits-all explanation. But the dogmatism was the same. Those who dared to disagree, or even to question the prevailing dogma in either era were dismissed -- as "sentimentalists" in the Progressive era and as "racists" in the multicultural era.