Pit bull advocates say the dogs are no different than any other breed. With correct training, pit bulls are completely safe. It's bad owners who give the breed a bad reputation.
A dog who is adopted as a puppy and who had been properly socialized is of course a better bet than a dog with an unknown history. But having said that, even dogs lovingly raised as puppies (and this applies to any breed), can display nasty behavior. A very good friend of mine adopted a little pup who ended up being around 15 lbs fully grown, a mutt of many small breeds. She has always been aggressive, she guards her food and the bed, and even though she adores my friend, she once bit her when she was asleep, because she was "guarding" her side of the bed. She also attacked the neighbor's teenage son, who she saw and played with, every day. He was just sitting down and tried to pet her as he normally did, and she went for his hand. This is just to illustrate that there is always an inherent risk with having a dog, a cat or any other domestic animal. They are just like people, sometimes they don't turn out quite the way you expected them.
Pit bulls are more likely to cause severe damage because of their breeding. They may not be more likely to bite or attack than other breeds, but when they do, the damage is much worse.
Starting about 25 years ago, my colleagues and I started to see disturbingly different types of injuries. Instead of a warning bite, we saw wounds where the flesh was torn from the victim. There were multiple bite wounds covering many different anatomical sites. The attacks were generally unprovoked, persistent and often involved more than one dog. In every instance the dog involved was a pit bull or a pit bull mix.
It's simply unnecessary to have the breed—there are plenty of other dog breeds that are demonstrably safer.
Based on my extensive experience, I believe that the risk posed by pit bulls is equivalent to placing a loaded gun with the safety off on the coffee table. In my opinion, these dogs should be banned. I know this is an unpopular stand in some circles, but how many mauled children do we have to see before we realize the folly of allowing these dogs to exist? ⠀⠀⠀⠀⠀⠀⠀ The arguments made by advocates of these dogs are the same arguments made by people who feel that assault weapons are an essential part of daily living. There are plenty of breeds available that peacefully coexist with human society. There is no need for pit bulls.