The selection of Senator Joe Biden to be Barack Obama’s running mate has revived the debate over a statement Biden made to The New York Observer in early 2007.

“I mean, you got the first mainstream African-American who is articulate and bright and clean and a nice-looking guy,” Biden was quoted as saying. “I mean, that’s a storybook, man.”

Now, we’re not going to deal with the question of whether his use of words like “articulate” and “clean” was racist or otherwise loaded, or whether he was slighting other “mainstream” African-Americans like Jesse Jackson, Shirley Chisholm or even Jackie Robinson. Instead, we’re going to focus on the comma that could have helped make his point clearer.

“Seldom has the distinction between a restrictive and a nonrestrictive clause been more important,” wrote Dean Mills, who happens to be the dean of the University of Missouri School of Journalism. “Without the comma, which is how every version I’ve seen is punctuated, it sounds as if Biden is saying that all other African-American candidates were not articulate, bright, etc.”

“But if you listen to the clips,” he continued, “Biden pauses significantly between ‘African-American’ and ‘who.’ So he could have meant (and almost certainly did): ‘I mean, you got the first mainstream African-American, who is articulate and bright and clean and a nice-looking guy.’”

Dean Dean Mills and I have had frequent run-ins over the serial comma, which he fervently believes in and I don’t. But this time, I’m on his side.

Biden was probably using African-American not as a noun, but, as Mills suggests, as an adjective, as in “the first mainstream African-American candidate” (though that, too, is open to interpretation). If the comma was spoken by Biden, but not included by his transcribers, the phrase “articulate and bright and clean” was a restrictive clause, meaning it applied only to Obama, and not to the body of African-Americans who came before him. That doesn’t mean he thought the other people were not “articulate and bright and clean”; it means he wasn’t speaking about them at all. (An even clearer way would have been “you got the first mainstream African-American candidate, and he is articulate and bright and clean.” But that would be changing the quotation, a definite no-no.) Without the comma, it was a nonrestrictive clause, meaning that it applied to every other African-American, and that he thought Obama was the first “articulate and bright and clean” African-American. That’s less likely.

It might be of little comfort to Biden to know about that comma now, given the kerfuffle that ensued over the actual words, but it could have saved him — and readers — a little bit of trouble.