"Most artists are really spilling the beans on the politicians [in their works]. They're saying the struggles that we go through every day in dealing with the police, they're saying the struggles we have to deal with just being black in the United States of America — a lot of politicians don't like that."
He's not knocking parents' concerns about the potential impact of lyrics. He says parents should learn what their kids are playing in their rooms. "Parents should definitely be concerned. I'm a parent myself — that's why I put the [warning label] sticker on there," said Campbell.
Kweli agreed that many rappers feel parental concerns.
"I'm a parent and I would say the vast majority of hip-hop artists are parents, so when you talk about parents, you're also talking about hip-hop artists. I know there are artists who I listen to who I would never play around my kids," he said.
Politicians: Regulate Yourselves
The summit also drew politicians, including Democratic Reps. Cynthia A. McKinney of Georgia, Bennie Thompson of Mississippi and Earl Hilliard of Alabama. FCC Chairman Michael Powell is also slated to attend.
"We're here to ask the industry to set up standards so it can regulate itself, so it can police itself. This would be in line with what the movie industry has done," Hilliard said.
He suggested rappers might prefer to rate their own content before the government does it for them, as proposed under a Senate initiative.
"Since we do not know the hip-hop generation, we do not know the hip-hop industry, we feel that those who know the industry can regulate it better," Hilliard said.
Rapper Treach of the Grammy-winning group Naughty By Nature agrees artists should be in charge of their lyrics.
"We created this whole culture so we have a right to control it," he said.
But don't expect Def Jam's Simmons to encourage rappers to change their words. "We absolutely are not trying to clean up anything," he said.
And, he jokes, this is just the beginning. "Eminem's records are fun, but there's much scarier records we want to make."
ABCNEWS' Zak Young contributed to this report.