Ben Carson on "volatile" past, trying to stab a friend

Republican presidential candidate Ben Carson, in defending against criticisms of his relaxed demeanor on the campaign trail, opened up about his past "volatile" behavior during an interview that aired Sunday.

"I have plenty of energy. But, you know, I am soft-spoken. I do have a tendency to be relaxed. I wasn't always like that. There was a time when I was, you know, very volatile," Carson told NBC News. "But, you know, I changed."

The retired neurosurgeon went on to explain that "as a teenager, I would go after people with rocks, and bricks, and baseball bats, and hammers." He also spoke about the time, at 14 years old, when he "tried to stab someone" -- a well-known story of Carson attacking a friend during an argument over preferred radio stations. He missed: the knife hit the teenager's belt buckle and snapped.

"Fortunately, you know, my life has been changed," Carson added. "And I'm a very different person now."

When pressed on some of his controversial statements, Carson said that "as people get to know me, they know that I'm not a hateful, pathological person like some people try to make me out to be.

"That will be self-evident," he added. "So I don't really worry about that."

In the wide-ranging interview on NBC News, the Republican contender also spoke about gun control and his stance in staunchly backing the Second Amendment.

"Noah Webster said that America would never suffer under tyranny if people were armed," Carson said, repeating an oft-quoted line from the campaign trail. But, "of course, we should be thinking about what can we do to keep dangerous weapons out of the hands of mentally unstable people." The two things, Carson added, "are not incompatible."

Carson also weighed in on the debate over abortion, just as Republicans in Congress launched a panel to investigate women's health care provider Planned Parenthood.

He is in favor of considering exceptions to his belief that abortion should be illegal, particularly if the health of the mother was at stake.

"If in that very rare situation it occurred, I believe there's room to discuss that," Carson told NBC News.

But for exceptions like rape and incest, Carson "would not be in favor of killing a baby because the baby came about in that way."

"All you have to do is go and look up the many stories of people who have led very useful lives who were the result of rape or incest," he added.

The presidential hopeful added that if a woman simply had an unwanted pregnancy, they should not have the right to terminate it. He compared it to slavery, despite acknowledging that "I know that's one of those words you're not supposed to say, but I'm saying it."

"During slavery, a lot of the slave owners thought that they had the right to do whatever they wanted to that slave. Anything that they chose to do," Carson said. "What if the abolitionist had said, you know, 'I don't believe in slavery. I think it's wrong. But you guys do whatever you want to do?' Where would we be?"