I don't believe in BSL, but I will never deny that certain breeds have characteristics that are more suited to people who can acknowledge and work with these characteristics in a positive and constructive manner.
chisa - I think you have misunderstood my comments to some degree (I am Moi but had trouble logging in under my normal log-in).
A Pug, regardless of who breeds it and how it is handled, will have very little aggression. It is a breed trait. It is born that way. It also will have very little prey drive. It will be a glutton and it will have an affable and friendly disposition.
A Border Collie, regardless of who breeds it and how it is handled, will have a high herding instinct, it will be highly intelligent and it will have high energy. It is born that way.
These are breed traits. The breeds were developed with these characteristics for various and different reasons.
If the dogs are handled incorrectly, these traits can develop into different things. The Pug may become obese and sluggish, the Border Collie may suffer from separation anxiety and become a compulsive 'chaser'. They are born with the traits that are the underlying reason for these issues though.
In breeds such as the APBT, the traits that these dogs were developed with are there, regardless of who breeds them or how they are handled. Poor handling will undoubtedly ensure that those traits show in a more negative manner.
We breed dogs not only for type, but for temperament.
If we can proclaim that we breed well rounded Pugs for example, and this is considered their 'nature', then we can not deny that another breeds temperament is only nuture related.
Some breeds are more prone to behavioural issues and that is in their nature. The nuturing may increase the severity and the liklihood of issues developing though.
Do I make more sense now?
I hate BSL. It is wrong. However, generalising about a breed is not neccessarily wrong. It is no more worng than generalsiing about anything else in life. We generalise about many things in every day life. We all hold generalised beliefs about different breeds of dogs, about cats, about women drivers. I concede that generalisations can be dangerous though but there is usually always a note of truth to generalisations.