Fundamentally it is just every man for himself, no holds barred. Libertarianism is a naturally-occuring-to-most-people from-the-individual-up "deal" that many propose to everyone they interact with.  I'll respect you if you respect me, let's follow these ideals and we will both (or all) prosper.  Human rights is the same kind of things and goes hand-in-hand with libertarianism.  You start from the reality of us being violent animals, and you end up with civility and prosperity.

Thinking about a "social interest", from the top down, is backwards thinking. It puts the cart before the horse. It doesn't arise out of concepts that mirror reality, it arises out of concepts that other people implanted in us to control us.... or at least so I think.