Even when worthwhile, war brings terrible costs and must not be undertaken lightly.

David Boaz is the executive vice president of the Cato Institute and has played a key role in the development of the Cato Institute and the libertarian movement. He is the author of The Libertarian Mind: A Manifesto for Freedom and the editor of The Libertarian Reader.

Boaz is a provocative commentator and a leading authority on domestic issues such as education choice, drug legalization, the growth of government, and the rise of libertarianism. Boaz is the former editor of New Guard magazine and was executive director of the Council for a Competitive Economy prior to joining Cato in 1981. The earlier edition of The Libertarian Mind, titled Libertarianism: A Primer, was described by the Los Angeles Times as “a well‐​researched manifesto of libertarian ideas.” His other books include The Politics of Freedom and the Cato Handbook for Policymakers.

His articles have been published in the Wall Street Journal, the New York Times, the Washington Post, the Los Angeles Times, National Review, and Slate, and he wrote the entry on libertarianism for Encyclopedia Britannica. Finally he is a frequent guest on national television and radio shows.

Benjamin Franklin said, “There never was a good war or a bad peace.” Given Franklin’s leadership in the struggle for American independence, we can infer that he did not think that there never was a war that was necessary, or a war that was worth its cost. But he reminds us that even necessary wars have terrible costs.

I thought about Franklin when I read Mark Helprin’s eloquent column on Memorial Day, which included these lines:

Though if by and large we ignore the debt we owe to those who fell at Saratoga, Antietam, the Marne, the Pointe du Hoc, and a thousand other places and more, our lives and everything we value are the ledger in which it is indelibly recorded.

It’s a timely sentiment, and we do indeed owe our lives and our pursuit of happiness to the freedom that America’s soldiers have sometimes had to defend. But I wonder: Does Helprin think that all of America’s wars have been necessary to American freedom? True, he doesn’t allude to any of our wars since World War II in his list of hallowed places. But he does mention the Second Battle of the Marne, the great turning point of World War I and the first battle in which Americans started experiencing the enormous casualties that Europeans had been facing for nearly four years. The problem is that World War I was a catastrophe, a foolish and unnecessary war, a war of European potentates that both England and the United States could have stayed out of but that became indeed a World War, the Great War. In our own country the war gave us economic planning, conscription, nationalization of the railroads, a sedition act, confiscatory income tax rates, and prohibition. Internationally World War I and its conclusion led directly to the Bolshevik revolution, the rise of National Socialism, World War II, and the Cold War. World War I was the worst mistake of the 20th century, the mistake that set in motion all the tragedies of the century. The deaths of those who fell at the Marne are all the more tragic when we reflect that they did not in fact serve to protect our lives and all that we value.

On this weekend we should mourn those who went to war, such as my father, who planned and participated in the liberation of Europe, and his brother who was lost off the coast of Normandy, and we should resolve not to risk American lives in the future except when our vital national interests are at stake.

This piece originally appeared on the Cato at Liberty blog.