i think the conservative ones will be dominant.
in the liberal communities who would be paying for the paternity tests and drug rehab centers and all the other cost associated with social decay?
i think liberal communities, as a whole, would self-destruct faster without a larger pool of people to steal from(through taxation).
I guess it depends on what we mean by liberal on social issues. I simply mean tolerable to other social opinions, not forcing others to pay for individual actions. For example, a private community with a contract stating you must not be gay, not do drugs, be in a commited monogamous relationship, etc to live there is completely valid, but I don't see how it would be any more dominant than the society which is socially tolerable of these issues, as long as they have the same economic system, and instead I would almost be tempted to say the opposite, given the one society prevents people from going there and associating with it.
I agree if people within the liberal community were forced to pay for other people, then it would decay faster, but only in an economic sense considering it simply wouldn't be that libertarian on the economic side. However, I believe in the absence of government (or at the very most, a government that enforced contracts and that's it) society would be much more liberal, or at least tolerable, on social issues. Look at today's youth, obviously not a good example on all fronts, but they tend to be more tolerable on social issues than previous generations. I don't think this trend would end given a libertarian society. I don't know a single libertarian under 25 that has any issue with gay/race/etc, whereas some older more paleoconservative libertarian types do, even if they wouldn't legislate against it.
So who would pay for costs of 'social decay'? - those individuals who decide to act in such manners.
I don't see how a society that is acceptant and tolerable, even encourages to a certain extent (the same as people encourage heterosexual marriage commitments today) of gay-marriage (or at least commited relationships, given the state would not be involved in marriage) is any worse off, and I would probably state the opposite for those that would condemn those individuals in their society would be less off. It's similar to that with a racist store owner (not that racism is equivilant with being against homosexual marriage but), if you prevent and limit who visits your business/society, you prevent ideas and money from going there.
For drugs, etc, obviously those in addiction are not beneficial for society, but I don't see drugs as a problem in itself, addiction is the problem. But I would say a society that is more tolerable, and accepts it as a medical problem of addiction and not a bad condemable action in itself would be better off. I personally wouldn't want to live in a society where I couldn't do what I pleased with my body on my own property, which if that was within the contract (ie: No drugs in our society), I'd consider it a viable contract if people wanted to live there under those conditions, I just wouldn't move there - and I don't even do drugs (other than alcohol, although that tends to be a conservative-acceptable drug).
I think Hoppe's argument is that conservative plan for long term (ie, drugs are pleasurable, but they're bad for your health in the long term so I don't do them; sex with multiple people/strangers is pleasurable, but bad for your health in the long run) where as liberals don't, which he then relates to economic investment and planning, and states therefore the conservatives would be better off. I haven't actually read his book, so I don't know if that's his actual argument, but I don't think that argument holds. I don't equate a specific social positions with economic ability, however I do equate social freedom to economic freedom. I don't think you can have one without the other. My body, my property, I do with it as I please, and can contract with any consenting adult.
I think this is all irrelevent though if we were given a truely libertarian society. Do what you want on your property and group with whomever you please, and I will do the same. That is the beauty of freedom.