Bayes' Theorem For Dummies—Dummies Like Richard Cohen
Trolling the universe this morning, Richard Cohen wrote a column arguing that it wasn’t racist of George Zimmerman to suspect Trayvon Martin of being a criminal because everyone knows that a disproportionate share of violent crimes are in fact committed by young black men.
I think what Cohen really means to be arguing isn’t so much that neither he nor Zimmerman are racists, but that racism is the correct social and political posture. That white people have good reason to fear black men, and that therefore all black men should be put in a subordinate position. But as a logical argument, Cohen here is falling afoul of very poor statistical inference. For example, the vast majority of newspaper op-ed columnists in America are white men just like Richard Cohen. But that doesn’t mean it’s reasonable to see a white man walking down the street and assume he’s a newspaper columnist. If you look specifically at Jewish men, you’ll see the stereotype that we are disproportionately represented in the field of political commentary is absolutely accurate. And yet it is still not reasonable to assume that some randomly selected Jewish man is a professional political writer. Even right here on the mean streets of Washington, D.C.—a city that’s legendary for its high rate of punditry—a clear majority of Jewish men are not pundits. It’s just a very rare occupation.
Here are the demographic backgrounds of the a list of the top 50 pundits in America in 2009, a list compiled by The Atlantic.
By the same token, the fact that young black men are disproportionately likely to be involved in violent crime in no way licenses the inference that you should stop random black men on the street and begin treating them like criminals.
For example, since moving to a majority black city ten years ago it is the case that 100 percent of the people who randomly assaulted me on the street were African-American. And yet that was a single incident on one day out of thousands. The overwhelming preponderance of black men I walk past on the street on a day-to-day basis—even the young ones, even the ones wearing hoodies—aren't committing any violent crimes.
Back on May 15, 2011, I wrote: "Was the beating of Matthew Yglesias a hate crime?"
If I were to start questioning every single black male teenager I come across as a criminal suspect, I would very much be engaged in unreasonable behavior. Now everyone makes mistakes, but the fact that Richard Cohen has been making this mistake in print for over 25 years leads me to think he just doesn’t care. He knows most young black men aren’t dangerous criminals, but he nonetheless thinks they should all be held under a cloud of preemptive suspicion anyway.
Sportswriter Damon Runyon (source of the great musical "Guys and Dolls") once amended the Book of Ecclesiastes:
"The race is not always to the swift, nor the battle to the strong, but that's how the smart money bets."