Pit Bulls' disposition (and all dogs really) has to do with how they are trained.
Agree completely. While there are breeds that are more dangerous than others, due to their size, or particular characteristics, the biggest reason certain Dogs are more prone to attack people or other animals is because of the way they are brought up.
Let's face it, a lot of the people who own Pit Bulls, own them because they want an aggressive dog, who can protect them. They often train them to be aggressive, or in many cases, abuse them, making them aggressive.
Now, of course, these are still animals, and no matter how well trained they are, if you treat them in the wrong way, or threaten them, they will fight back. And this is where big, strong dogs like Pit Bulls can be dangerous, and why you should not have them around kids (who think playing with them involves pulling on their ears and trying to ride them), but if you don't abuse the dogs, and respect them for what they are, a pit bull can be just as safe as any other dog.