By THOMAS CHATTERTON WILLIAMS

What’s on President Obama’s iPod? A wide range, he told Rolling Stone magazine last week, from the jazz of John Coltrane to the ballads of Maria Callas. And more: “My rap palate has greatly improved,” Mr. Obama noted. “Jay-Z used to be sort of what predominated, but now I’ve got a little Nas and a little Lil Wayne and some other stuff, but I would not claim to be an expert.”

Expert or not, that’s the wrong message for the president to be sending black America.

Does Mr. Obama like Lil Wayne’s “Lil Duffle Bag Boy”? In that song, the rapper implores young black men to “go and get their money” through round-the-clock drug hustling. And with Lil Wayne, it’s not just an act: The rapper is currently serving a one-year term on Rikers Island after being caught in New York with drugs and guns stashed in his Louis Vuitton overnighter.

Lil Wayne is emblematic of a hip-hop culture that is ignorant, misogynistic, casually criminal and often violent. A self-described gangster, he is a modern-day minstrel who embodies the most virulent racist stereotypes that generations of blacks have fought to overcome. His music is a vigorous endorsement of the pathologies that still haunt and cripple far too many in the black underclass.

Thus President Obama has conveyed his taste for the rapper behind lyrics like:

Put that white widow weed in the cigar and puff

look, ma, I’m trying to make a porno starring us

well not just us, a couple foreign sluts

Naming thuggish rappers might make Mr. Obama seem relatable and cool to a generation of Americans under the sway of hip-hop culture, but it sends a harmful message—especially when, in black America, some 70% of babies are born out of wedlock.

More from Lil Wayne, a native of New Orleans, the nation’s perennial murder capital, who devotes his ingenuity to making black-on-black homicide sound fly:

We put that steel on

red beam, safety off

murder scene, tape it off

redrum, tomato sauce

Just as disturbing is Mr. Obama’s appreciation for Jay-Z, the rapper and unrepentant ex-drug dealer whose real name is Shawn Carter. Not only did Jay-Z earn a mention from the president in Rolling Stone, but he’s been photographed sitting in Mr. Obama’s chair in the White House Situation Room.

Mr. Obama is certainly not responsible for hip-hop’s grip on black America, or for Mr. Carter’s ideas and behavior. But what president would ever let Marilyn Manson drop by the White House? Is Jay-Z any better?

In the song “Show You How,” Mr. Carter—who also calls himself “Jay-Hova,” as in God—rhymes:

Listen man, get a crate, some crack and some house slippers

a newspaper, a lookout boy, and get your chips up

or get a gun, a mask, an escape route

some duct-tape’ll make ’em take ya to the house

For so many black Americans, Barack Obama is appealing and promising precisely because he represents a powerful, necessary alternative to Jay-Z’s version of blackness.

That’s why I cheered when Mr. Obama, then a little-known state senator, inserted himself into the cultural debate during the 2004 Democratic National Convention: “Children can’t achieve unless we raise their expectations and turn off the television sets and eradicate the slander that says a black youth with a book is acting white,” he declared. And it’s why I cheered again last year when he told an NAACP gathering that, “Our kids can’t all aspire to be LeBron [James] or Lil Wayne. I want them aspiring to be scientists and engineers, doctors and teachers, not just ballers and rappers.”

The president is entitled to his friends and aesthetic tastes. But he undermines his own laudable message and example when he associates himself with a hip-hop culture that diminishes blacks.

Mr. Williams is the author of “Losing My Cool: How a Father’s Love and 15,000 Books Beat Hip-Hop Culture” (Penguin, 2010).

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