It was once expressed to me like this - If by some chance you happened to get shrunken down to 4 inches tall - your dog would still love you the same. Your cat on the otherhand would eat you.
Like my mom's former "killer yorkie". That dog was so vicious-my brother and I used to tell her he was the perfect size for drop kicking like a football. Her current yorkie is obnoxious enough to pick a fight with my norwegian elkhound, but is not otherwise vicious.
Well, I might not be he most popular guy in this thread :D
IMO, any dog over a certain size is capable of harming humans. As such, the owner of any largish needs to understand a few things about dog behavior and the breeds temperament.
First, it is damn near impossible to get a Golden Retriever to attack a human. Their temperament is so docile and friendly as to make them useless as guard dogs. On the other end of the spectrum we have dog breeds that are quite capable of being trained to attack humans. dobermans, shepards, pits, rottweilers, etc.
This does not mean they are inherently dangerous as pets. Properly raised and treated they can make good pets. BUT, far too many people have no clue what they are doing and should not be allowed to own dogs with the size and "potential" temperament to be dangerous.
For example, if you own a 120 pound rottweiler, you better understand pack mentality. Sure, he is gentle as a lamb with your little kids and wife. But a stranger comes to the door and makes any move the dog construes as aggressive and he may attack if he has not been properly trained. For that matter, if the dog becomes confused as to WHO is the pack leader, you may have a problem. This little factoid eludes a lot of people who get a big dog for protection and are essentially inviting a time bomb into their house. If you can't kick your own dogs ass you better know how to train it.
Add to this too many people get large dogs and do not give them the exercise and attention they need. They can become dangerous. Consider if YOU were forced to live in a small apartment never leaving for years on end. You'd snap too.
I don't approve of any regulation for dog "breeds". And the term "pit bull" is used like "assault weapon" by the media to spice up stories and has caught on. It sucks.
IMO we have very few issues with dogs. I'd love to own one but the wife unit says no :(
But if I did, it would be a small dog so I would never have to worry about it harming anyone. Small dogs can give as much love as big ones and thats what its all about :)