Anti-state libertarians can't seem to see the importance of context -- that what may be wisdom in the confines of Lockean civil society could be utter folly in the Hobbesian state of nature. And so, in the domestic sphere, they indulge in fantasies about replacing government with totally privatized law enforcement. And internationally, they contend that making war beyond one's borders is inconsistent with the defense of liberty.
Lindsey does not explain why he thinks that private law enforcement is a fantasy. The rest of his post is devoted to arguing that war can serve liberty: "there is great truth in Randolph Bourne's line that war is the health of the state, but it is not the whole truth. War, for all its horror, has just as surely served as the midwife of freedom."
"Just as surely"? No way! Historically war has occasionally served the cause of liberty. But that only in a qualified way, and also fairly rarely. And if we distinguish wars with at least one party as a non-state (i.e. revolutions), I think there are very few examples, if any, of war serving the cause of liberty.
Sometimes one state conquers another (or takes territory), and the winner is a freer state than the loser. Although the occupants of the freer state see their liberty decrease because of the standard need of the state to steal property and enslave people to use in the fight, the net liberty lost by the citizens of the victor is comparable to the gain in liberty of the citizens of the losing state. So for example when France was liberated in WWII it went from being controlled by Nazis to a new republic - clearly a big improvement for the French. But Americans paid the price in lost liberty.
Furthermore, we should not evaluate the effect of wars by looking at only some of the participants. Rather, the effect of war on liberty needs to take account of all the effects of the war, on everyone. Of course it is impossible to draw any firm lines around history; did WWII start in 1937, 1938, or 1939? But surely if we look at the whole picture of WWII, we see the following. All of the western democracies got more socialistic. That is we all lost liberty. All of the axis countries, which were conquered, got a lot freer. (East Germany excepted.) All of eastern Europe, which had been in varying states of liberty, fell under communist rule and got a lot less free. And Soviet Russia was infused with a new lease on life, gaining legitimacy from the struggle against the invader that propped up the regime for another 45 years. All results considered, WWII was a disaster for freedom.
Madmen occasionally do get in control of states (though in Hitler's case, that was itself a long-drawn out effect of WWI, at least in part). The question is what to do. WWII turned out as it did: a loss for freedom but at least the madman was unseated. Lindsey and other warmongers regard the result as self-justifying. I don't; for I believe there were many other paths that history might have taken. America might have stayed out of the war, and Hitler still defeated.
More generally, there is always a danger in drawing lessons from history, because history is untestable. Lindsey is certainly within reason to believe that the world is more free today "because European military power checked and then repulsed the spread of Islam". But he cannot prove that; perhaps had Islam conquered Europe it would have simply replaced Christianity as the faith of the liberal, modern West. Most of his other examples are similar; a war happened, someone won, and in subsequent history that someone was at some point a champion of liberty. But correlation is not causation.
When I examine the examples Lindsey uses to try to show that war is the "midwife of freedom", I find nothing I would regard as at all conclusive. In almost all of the cases he cites, the war in question preserved some sort of freedom for one set of people, at a cost in lives, capital, and freedom, of a larger set of people. The result is probably a win for the set of people whose liberty was preserved, and just as probably it is a loss for those paying the price. Consider Korea, for example. At large cost the US preserved what amounted to a military dictatorship until the 1980s. If Korea had been forcibly unified by Communists in 1948, would it have in time evolved as China seems to be doing? Was war in fact necessary at all? Perhaps so, but it is not clear to me. Lindsey may be comfortable making that tradeoff; I am not.
Of the other examples Lindsey gives, the only one that needs additional comment is the result of the American Civil War (which was not, in fact, a civil war, but that's the label it has). Yes, the slaves were freed. But that means less than it seems, since subsequently the North sold them out and allowed them to be reenslaved, albeit in a kinder and gentler fashion than previously. The result was still a net plus for the ex-slaves; but again looking at the whole picture: at what cost? Not just in the horrendous loss of life, but that the states lost the most vital liberty: the right of secession. Had the South been allowed to leave peacefully, the fugitive slave laws would have been instantly repealed in the north. In time, the north would have emancipated its slaves with compensation, perhaps with a few defecting border states, perhaps not. In any case, with the border in walking distance and no federal agents to hide from, a torrent of slaves would have poured out of the South into the North, freeing themselves. Slavery would have ceased to be economically viable, and it would have thus died a lingering, quiet death, ending peacefully just as it did in almost every other country in the world. Indeed, the crypto-slavery of sharecropping itself died, not by the sword, but by economic progress making the practice uncompetitive. And the political slavery of the segregationist south was killed, not by war (though federal coercion had its part), but by the committed peaceful activism of the civil rights movement. There is indeed a lesson here for libertarians, but it is not what Mr Lindsey thinks.
Meanwhile, the right of secession is something we vitally need these days, but it is gone. I hope with all my heart that Quebec manages to pull it off some day. For if they do, Canada will break up, and the libertarian tinged West will then become a very attractive place to be; more so than these United States.