What's Right With Libertarianism
Surely, in such a hugely diverse set of ideologies as libertarianism, there must be something right. And just as surely, opposing libertarianism does not mean believing in the exact opposite. Here is where the valid overlap between libertarianism and other ideas can be analyzed. it turns out that libertarians are half-right most of the time.
Markets are a solution to an important class of optimization problems (get Daniel Davies quote.) But the real world has many other classes of optimization problems where markets are grossly imperfect solutions. The technical term is second-best, and there are many other second-best solutions such as government provision. It would be foolish to disallow markets where they are a first-best solution, and insist on them where they are merely a poor second best solution (territorial defense, for example.)
Well-functioning markets that fit the free-market model need no government interference. However, that's relatively rare. Most industries are oligopolistic or monopolistic, have barriers to entry, or would suffer from failures of market requirements without government interference. Not to mention strategic issues of international markets. Currency.
Liberty is a hugely vague term, but that doesn't mean we don't value any sort of liberty.
Probably much more harmful than a regulated system of drugs would be. Most liberals would agree with that, and many conservatives too. Many have been saying it for decades, long before libertarianism "bloomed" in the 70s. But libertarians only have one answer: deregulate everything. Legalize date-rape drugs. Legalize poisons for committing murder. Legalize giving or selling narcotics to children.