"I said, 'Look, I need to be able to stop the fight if this fighter cannot intelligently protect himself.' They said, 'Well, OK, that’s fine. If they’re hurt to the point where they’re out, you can stop the fight.' So I use that term. If you cannot intelligently defend yourself, I am going to stop the fight. There’s going to be variances in it. There is nothing that can be written absolute in terminology that is going to make it to where everyone goes by the same quorum of, 'This is what it is.' I know based on all of the fights I’ve done and what I am looking at, I look at certain things. When I teach people, I teach them about body position and what the fighter is telling you.

I see fights go on all of time. You watch UFC 95 -- there were fights that were going on, and I know the fighter has quit. The fighter that is losing has gotten to the point where he’s stopped. He’s stopped fighting; he is surviving. And is he intelligently protecting himself? Absolutely not, and it’s time to get him out of the fight because he has mentally given up in the fight. He is telling you that by his body motions and what he is doing, but [refs] let those fights go on. There are people out there that say they should until these guys can’t move. Well, that’s ridiculous. When it comes to being able to perfectly articulate what “cannot intelligently defend himself” is, there’s never going to be this absolute.

But you’ve got to have enough smarts as far as if a guy is face down on the ground and his hands are down, he is taking blows to the side of his head, and he is not moving -- that man is not intelligently defending himself. It takes no training to do what he is doing. Intelligent defense, on the other hand, is if you look at someone who does get hit and goes backwards and their feet come up and their hands are out, they’re in a position to intelligently defend themselves. Are they going to? I can’t say that. But at least they’re in a position to do it. And they’re trying to show that, 'I know I’ve got to do something.' And as the punch comes, they’re in a position to at least deal with it. If they don’t deal with it well, then we might have to stop it with the next punch."

-- "Big" John McCarthy talking to TJ DeSantis about intelligent defense, what is means, how it's evolved and how he applies the concept to refereeing.