Well I guess it depends on what you consider pure capitalism. I guess you could say it's no government at all, anarchy/darwinism, whatever you want to call it. But then you'd have to also say that the entire world is living in pure capitalism right now, because in this definition of capitalism governments will inevitably spring up, hence the result is the entire world as it exists today. So then you end up with capitalism not really existing or meaning anything at all.

I see capitalism as a nation with a limited government; only an organization to maintain order, defend the nation, and regulate monopolies. Now the trick is to create a government that is empowered by the entire people, not just a chosen few as socialist and communist governments usually end up. I think the framers of the constitution did a good job of this.