Well, Alan Kay's definition is just one definition and as evidenced by the rest of this thread, it's far from being universally accepted and definitely not the

Well, Alan Kay's definition is just one definition and as evidenced by the rest of this thread, it's far from being universally accepted and definitely not the definition used in the mainstream "OO" languages. Further, that email thread is far from being a formal definition. In that email there's a pointer to a ISO standard doc, but that's hardly authoritative either. It seems like every language (and every programmer) has their own idea of OO, which is why I consider it quite apt to call it "ill-defined". That's not to say that OO programming itself is bad, more that the term "OO" is bad.