capitalism involves a system of voluntary cooperation, which goes entirely out of the schema of "natural" behavior.
I don't remember Adam Smith ever saying anything like that. In fact, quite the contrary.
As to this "contrary" business: I'd be most glad to see your cites. Meanwhile, we weren't talking about what A. Smith said, but the way he was interpreted by Marx. Marx thought Smith was pretty good, BTW. But in Marx's view, he just wasn't quite smart enuf to draw the proper conclusions from his own statements. Marx comes along to "correct them," you see....
If you want to open this discussion to include an evaluation of the work of Adam Smith according to Karl Marx, I'd be completely open to that development.