Sandman is right, so why pick on pitbulls? My answer is stated above. This breed was "invented" to fight. Pure and simple.
About ten days ago my sister's husband's brother (um...yea, got that right. Does that make him my brother-in-law? Don't think so, but could be wrong) came across a German Shepard strolling around the neighborhood with a leach dragging along the ground. He knew who the owner was, but didn't know the guy personally and had never been to his house before. Anyway, my sister's...ummm....my brother-in-law decides to take the dog home. He walks it up onto the owner's porch and knocks on the door and the dog attacked him. Really badly. He is all cut up and stiched, on his arms, his legs and on his back.
Crazy story, but it shows that Shepards are bred with a guard instinct and serve that purpose incredibly well. Too well, in fact. I've ALWAYS owned Shepards or Shepard mixes in the past. Now, with 3 little kids I'm not going to risk one of their friends getting mauled because the dog perceived a threat. It can happen with Shepard...love them, my last one died after 12 years of being my best friend, but can't own one now.
Pits have been bred to fight. I've known lots of them and a couple of good friends own one now. They can be great pets and very loyal and obediant. But they can snap for no reason and lord help the animal or human that is on the receiving end of a pitbull attack. As Udie's story highlights, when there is more than one involved in an attack something's gonna die.
I don't advocate a nazi approach at all. Let the existing pitbulls live out their lives. Just don't breed them anymore. What is the point? They were bred for a ridiculous purpose that is now univserally condemned.