Explain Please

Example:
You tell a boy, "If you touch that dog, it's going to bite you."
Boy touches the dog and the dog bites him.

Ok, so now, tell me how it makes sense that this boy tries to convince the dog that it is not his fault the dog bit him, rather the dogs. EVEN THOUGH he was warned, time and time again that if touched the dog would bite him. Perhaps he was testing the dog, but in the end, whose fault is it? The dogs? The boys?

I tend to think it's the boys fault. He was warned against a certain behavior, touching the dog (for the last 2 years mind you) and he did it anyway. In the past he touched the dog and it may have growled and bared its teeth but never lived up to the bitting potential it had. However this time the dog bit and now it's supposedly the dogs fault. Hmmmm....I guess he just didn't believe he'd get bit. Sucks to be him. Now he's in the dog house. More commonly known as his brothers couch.