I agree that those who advocate communism always seem to fall back on what is essentially the "Well it's never been tried out properly" argument, which I don't find convincing at all. It also happens to be the argument I hear most frequently from libertarians.

Essentially, claiming that your economic theory will only work once a dramatic, complete, state-wide change as occured is a non-starter. Nations advance by degrees, and if there aren't small moves that can be made towards the goal that provide evidence that the theory is sound, it would be foolish to believe that big moves will fair any better.

I would genuinely like to see examples of where libertarianism ideals have been tried on a small to medium scale and been successful. And if there aren't any, same question as to jasonisalive: why is there such confidence among libertarians that it works in the real world?