Libertarians value liberty, of course and set of values, that by themselves lack adequate moral glue to bind society together. A world in which libertarian values prevail could only survive if civil society supported the social norms of a conservative world-view. Such a view might hold that the individual has a larger duty outside of oneself. The self is not the highest end, nor the most important societal construct. Haidt discusses this in his essay on why people vote Republican, in his discussion of his time in India. Libertarians may desire a society in which conservative norms are not enforced by the government, but the norms are necessary. More on government later.
The other reason is that libertarians will never form an outright majority unto themselves. Although this is my opinion, Jonathan Haidt's research points to this result as well. Libertarians share with liberals that they don't hold as broad a spectrum of moral values as do conservatives. As a result they will probably not achieve a majority status (nor will liberals). Only by allying themselves with the least statist leaning groups between left and right can libertarians achieve the freedom and small government that is their goal. Some libertarians take a different view, and desire not only a government that doesn't invade the bedroom, but a society that takes no moral view of what happens there as well. That is unrealistic and counter-productive. We know that family disintegration due to absent fathers is the key predictor of poverty in the western world. Restoring social norms would go a long way towards reducing the demand signal for welfare and prisons, two key components of big-government.
It is less obvious that conservatives need libertarians, but they do. First, their votes and energy are necessary to do battle with the forces of statism. On any individual issue, the pressure for government to "do something" often seems compelling. Only a firm adherence to principles, which libertarians seem better equipped to do, can beat back these impulses. Second, conservatives forget at their peril that the use of government to achieve their desired social ends usually ends badly for them. From the death of the church because it was identified with the monarchy in old Europe to Republicans becoming identified as the party of big government before the 2006 elections, marrying conservative social ends to the coercion of big government has been a loser. Further, funding big government conservative programs undermines the principled arguments for limited government.
The tension between the two perspectives often plays out in the non-economic issues. Three examples.
Immigration. The libertarian argument is that free movement of people is important for freedom and economic prosperity. Conservatives argue that open borders will undermine the rule of law, and allow those who don't share our values to weaken the nation's commitment to limited government. Further, both libertarians and conservatives suspect a desire on the part of the left to increase welfare rolls and the overall dependency rate by allowing vast amounts of new immigration. My solution: Secure the borders to champion the rule of law, have a vastly increased guest worker program to allow free movement of labor, but limit the path to citizenship of the guest workers.
Marijuana. Conservatives view the abuse of alcohol and many other drugs are symptoms of societal ill. Condoning their use weakens society because drugged up and drunk folks act stupidly and harm others. Libertarians know that prohibiting their use results in black markets, violence and money flowing to criminals. My solution: Legalization; but it is up to we the people to establish that in civil society drunkenness and druggedness are not acceptable.
Gay marriage. Libertarians don't want to interfere with people's right to make their own arrangements for love and economic union, so gay marriage isn't a problem for them. Conservative objections primarily rely on tradition and religion. However, these arguments are legitimate. Government sanctioning gay marriage yields it protected status. Some time ago I took grief for telling a young gay man that I objected to gay marriage because it infringed on my freedom of speech. That post still has this blog's record for most comments. Events since I have made my point, as Chick-Fil-A's vilification showed. My solution: Government out of the marriage business. I would like to see churches draw up marriage contracts and record marriages as they once did. If people want to just live together, fine by me. And if gays wish not to be married in church, but draw up a civil contract that lays out the marriage agreement, that should be their right. But I shouldn't be forced to acknowledge that they are married if I don't want to.
That's all for now, I hope to expand this article into a longer post.