Pick up Thomas Sowell's A Conflict of Visions for a truely through insight into the difference between, what he terms, the Constrained and Unconstrained Visions of Mankind. Sowell points out that libertarians are one of the peculiar few that have a blended group of positions. The Unconstrained vision holders, Sowell maintains, concieve as man as "perfectible" and society capable of being systematized to achieve such perfection. The Constrained vision, on the other hand, believes man to forever be a blend of good and bad, virtueous and evil and largely improveable, but not perfectable. Salvation is not worldly, but instead Godly or historically viewed only.
I have read several of Sowell's books but not that one. I will pick it up next time I order some books from Liaises Faire.
I suppose there are some individuals within every political camp who are forever idealists. The communists/socalists seem to have the majority but I guess there are some utopians within the libertarian party as well.
I think that the misperception that libertarians all think man is inherently good comes from our belief that man should be free. Authoritians cannot reconcile their belief that man is inherently evil and therefore must be controlled, with the concept of individual freedom and personal responsibility.