IQ researcher Emil Kirkegaard tweeted this:

Jason, what are you trying to get at here?? pic.twitter.com/bpjshPVZmL

— Emil O W Kirkegaard (@KirkegaardEmil) September 22, 2022

It looks like  Jason Stanley, an American philosopher who is the Jacob Urowsky Professor of Philosophy at Yale University, and will tell you he is the Jacob Urowsky Professor of Philosophy at Yale University on Twitter has deleted this May 2022 tweet when the Unfortunate Implications were pointed out, but the actual op-ed he co-wrote is still online:

About 9 percent of the world’s prison population is black American (combining these two studies). If the system of justice in the United States were fair, and if the 38 million black Americans were as prone to crime as the average ethnic group in the world (where an ethnic group is, for example, the 61 million Italians, or the 45 million Hindu Gujarati), you would expect that black Americans would also be about 9 percent of the 2013 estimated world population of 7.135 billion people. There would then be well over 600 million black Americans in the world. If you think that black Americans are like anybody else, then the nation of black America should be the third largest nation on earth, twice as large as the United States. You can of course still think, in the face of these facts, that the United States prison laws are fairly applied and colorblind. But if you do, you almost certainly must accept that black Americans are among the most dangerous groups in the multithousand year history of human civilization.

Is the United States a ‘Racial Democracy’?  by Jason Stanley and Vesla Weaver January 12, 2014 7:00 pm

What Stanley is implying is that America's laws must enforced unfairly, or blacks wouldn't go to jail so much more than whites. He doesn't seem to understand the differential crime rates. This what Steve Sailer calls Kendiism after Ibram X. Kendi, who thinks that if black kids score lower on standardized tests, there's something wrong with the tests.

Stanley writes

Blacks are not necessarily having these encounters [with police] at greater rates than their white counterparts because they are more criminal. National surveys show that, with the exception of crack cocaine, blacks consistently report [I.e. self reporting] using drugs at lower levels than whites. Some studies also suggest that blacks are engaged in drug trafficking at lower levels. Yet once we account for their share of the population, blacks are 10 times as likely to spend time in prison for offenses related to drugs.

This was written in 2014, when crime in New York was at a much lower rate than it is now, thanks largely to Bloomberg continuing Giuliani's anti-crime policies, including having the NYPD encounter, so here are some figures from that era, showing that blacks are much more dangerous than whites:

• The evidence suggests that if there is police racial bias in arrests it is negligible. Victim and witness surveys show that police arrest violent criminals in close proportion to the rates at which criminals of different races commit violent crimes.
• Both violent and non­violent crime has been declining in the United States since a high in 1993. 2015 saw a disturbing rise in murder in major American cities that some observers associated with" depolicing” in response to intense media and public scrutiny of police activity.

Crime rates

• There are dramatic race differences in crime rates. Asians have the lowest rates, followed by whites, and then Hispanics. Blacks have notably high crime rates. This pattern holds true for virtually all crime categories and for virtually all age groups.
• In 2013, a black was six times more likely than a non­black to commit murder, and 12 times more likely to murder someone of another race than to be murdered by someone of another race.

Interracial crime

• In 2013, of the approximately 660,000 crimes of interracial violence that involved blacks and whites, blacks were the perpetrators 85 percent of the time. This meant a black person was 27 times more likely to attack a white person than vice versa. A Hispanic was eight times more likely to attack a white person than vice versa.

Urban centers

• In 2014 in New York City, a black was 31 times more likely than a white to be arrested for murder, and a Hispanic was 12.4 times more likely. For the crime of “shooting”—defined as firing a bullet that hits someone—a black was 98.4 times more likely than a white to be arrested, and a Hispanic was 23.6 times more likely.
• If New York City were all white, the murder rate would drop by 91 percent, the robbery rate by 81 percent, and the shootings rate by 97 percent.
• In an all­-white Chicago, murder would decline 90 percent, rape by 81 percent, and robbery by 90 percent.

See Watch Jared Taylor Talk About THE COLOR OF CRIME, 2016 Revised Edition   for more and if you're interested in the subject of "driving while black", read "Racial Profiling" And Bad Black Drivers: Blacks Speed Twice As Much As Whites And "Speed At Reckless Levels Even More"

I don't necessarily think that blacks are necessarily "among the most dangerous groups in the multithousand year history of human civilization."

They're just the among most dangerous groups in the United States of America at the current time, and the incarceration figures represent America being more civilized than Haiti, South Africa, Venezuela and Brazil.