Even if one believes that it’s moral to spill American blood and (forcibly extracted) American treasure to destroy evil regimes that do not threaten us, killing many of their innocent subjects in the process, one cannot embrace war-for-liberation without abandoning the libertarian’s skepticism about power. Libertarian interventionism—unlike libertarianism proper—depends upon a blithe trust in government’s competence and benevolence.
Libertarian interventionists trust the government to perform social engineering magic, transforming tribal despotisms into commercial republics. It’s surpassingly strange that many of the same people who think the federal government’s too ham-handed to run a retirement program, fight teen pregnancy or intelligently manage a war on poverty think the same government is capable of remaking whole societies and establishing limited, constitutional government and the rule of law where the necessary preconditions don't exist. (It would help, I suppose, if more than a handful of the nation-builders currently on staff spoke the nation’s language or even knew the alphabet.)
Libertarian interventionists trust the government to successfully manage the rights-maximization project abroad in the face of more uncertainty even than that which confronts a domestic central planner. The one certain thing about any war is that the unintended consequences vastly outweigh the intended ones. We can’t be sure that the bad unintended consequences will always outweigh the good, but the unplanned aftereffects of past crusades have been horrific enough to counsel against fighting unnecessary wars. Woodrow Wilson took us into World War I, as he said in his 1917 war message to Congress, “to fight thus for the ultimate peace of the world and for the liberation of its peoples, the German peoples included: for the rights of nations great and small and the privilege of men everywhere to choose their way of life.” He ended up creating the conditions for a punitive peace that would help give rise to Adolph Hitler and the next “war to end all wars.”
Libertarian interventionists trust the government to remain faithful to the rights-maximization project across successive presidential administrations, and not warp the project to its own, unlibertarian ends. We ought to remember how quickly armed evangelism can turn into contempt when the objects of our charity resist. Speaking to a group of Methodist church leaders in 1899 President William McKinley explained his decision to annex the Philippines, saying he wanted “to educate the Filipinos, and uplift and civilize and Christianize them, and by God’s grace do the very best we could by them, as our fellow-men for whom Christ also died.” Soon enough, the United States was embroiled in guerrilla warfare that killed some 200,000 objects-of-uplift. Mark Twain suggested that the new Filipino flag should copy the stars and stripes, but replace the white stripes with black and the stars with skull-and-crossbones. Is it so far-fetched to envision a similar shift occurring in our current struggle to liberalize Islamic theology through force-of-arms?
Finally, libertarian interventionists trust the government to restrain itself at home while it’s unleashed abroad. But an outlook that says it's our mission to overthrow tyrants, regardless of whether they threaten us, is a prescription for permanent war and a recipe for state empowerment. “Of all the enemies to public liberty war is, perhaps, the most to be dreaded, because it comprises and develops the germ of every other,” wrote James Madison in 1795. As Robert Higgs documents in Crisis and Leviathan, today’s enormous administrative state is largely a product of power seized under claims of wartime necessity.
Perhaps there are no immutable laws of history; perhaps we can have a nightwatchman state with a half a trillion dollar defense budget—a government big enough to liberate the world, yet small enough to mind its business at home. But taking that bet would reflect the triumph of hope over experience.
Libertarian interventionism is an oxymoron. Libertarianism views the state, in Washington's phrase, as, “like fire… a dangerous servant and a fearsome master." As David Boaz has suggested, the libertarian's rules for government echo Smokey the Bear's rules for fire safety: keep it small, keep an eye on it and keep it contained. Libertarian interventionism sets government free, hoping liberty will emerge from the blaze. But once you've stopped viewing war as--like the state--a necessary evil, and started to view it as a force for good, you're well on your way to getting burned yourself.