OK, I see what is going on. I believe they were likely correct and basing their opinion directly from observational data. Syphilis was rampant and education was extremely low.
You think they were wrong, and assume observational data would refute it.
>> [list of stereotypes] contribute to […] the prevailing indifference with regards to treatment.
>> the promise of medical treatment […] secured subjects' cooperation in the study
However, you're right: I was actually using the heuristic "racists are full of shit". This heuristic is pretty useful, because it means you can do useful things with your life instead of analysing and refuting bullshit racist argument #453054624.
Characterizing "rather low intelligence of the Negro population" (not educational attainment, but "intelligence") as "likely correct" is shocking. But it's also not an uncommon perspective on HN. Lots of "The Bell Curve" truthers here.
I think educational attainment and intelligence are correlated, and understand the quote to be in relation to a specific group, time, and place (and not race as a category).
Individuals arent statistics, but environmental circumstances have profound impact on cognitive development and intelligence measures.
You think they were wrong, and assume observational data would refute it.