I will grant that certain breeds of dogs have what dog handlers call "a higher drive" than other breeds, and that those breeds are also better equipped to inflict damage than many other breeds. Those would include Pits, Pinschers, Dobies, German Sheperds, Malamutes, etc. BUT... the way the dog turns out is largely the product of that particular owner's abilities or attitudes as a dog owner. In a way, arguing against ownership of certain breeds of dogs is a little bit like arguing against ownership of certain types of guns...
"Why do you need an AR15 (or substitute Barret M82, or Remington 700 XCR Tactical in .308, etc., etc., etc.)? It's nothing but an eeeeeeeeevil assault rifle designed to do nothing but kill humans!!"
"But sir, it is the intent behind the gun that makes it evil, not the gun itself."
"BALDERDASH! Outlaw them, I say. If we make them impossible to get, then you can't do anything bad with them."
It is dangerous ground on which to stake a claim, as it can be used against you. It assumes that the individual dog owner/gun owner is already a guilty person, and that the individual dog/gun is a bad thing that must be removed from society. Arguments based on eliminating dogs that are better equipped by nature to injure with a bite than other dogs are identical to the arguments that some guns are less morally defensible than others because of caliber, rate of fire, or magazine capacity.
If the person owning the dog is a dangerous cretin, his dogs will be dangerous dogs. If the person owning the dog is a respectable citizen who exercises good judgment, his dogs will be respectable citizens with good judgment. Far better to eradicate dangerous cretins and get those dogs into good homes populated by people who can manage a high drive dog.
I realize that I probably won't convince those that want to kill all pit bulls, but I do wonder if you have thought this completely through based on the example I've given above.
That's my 2¢, now I've got to duck and run. /ubbthreads/images/graemlins/grin.gif