American foreign policy is based on deep convictions. Those who shape it believe the United States is the indispensable nation that must lead the world; this leadership requires toughness; and toughness is best shown by threatening or using force. Beneath these beliefs lies the assumption that the United States knows more and sees further than other countries.
Many liberals embrace this dogma. That makes sense. It emerges from the liberal tradition, which imagines that humanity is steadily progressing toward a perfect world in which no one will go hungry, warlords will disappear, diseases will be cured, and people will cooperate for the common good.
Any true conservative would find this preposterous. Liberals have an expansive, optimistic view of what they can achieve in the world. They see themselves as a force for good and can be tempted to crash into other countries to "help" them toward "modernity." Liberalism contains within it a sense of evangelical mission, which sometimes leads to we-know-best arrogance.
Conservatism, by contrast, is a live-and-let-live ideology. By nature it is prudent, careful, and restrained. Conservatives do not believe that any country can solve the world's problems or is called to do so. They want to leave other nations alone, not remake them. That makes restraint in foreign affairs an essentially conservative doctrine.
Why, then, do so many self-proclaimed conservatives vote for lavish defense budgets, favor maintaining hundreds of military bases around the world, and support foreign wars? It is because they have left true conservatism behind. The vision of an exceptional America, dominating the world and shaping the fate of nations near and far, has seduced them away from conservative values. Many Republicans in Congress vote to reduce government's role in the lives of Americans but promote interventions aimed at increasing our role in the lives of foreigners.
It was not always so. Our most anti-interventionist president was a conservative Republican, Herbert Hoover. He had worked in a dozen countries and saw that, as he said in one speech, many people in the world view the United States as "a new imperial power intent upon dominating the destinies and freedoms of other people." After taking office in 1929, he ended Marine occupations of Nicaragua and Haiti and turned down appeals to intervene on behalf of American companies in Mexico, Cuba, Honduras, El Salvador, Panama, and Peru. Hoover is the sterling exemplar of the Republican Party's rich anti-imperial tradition.
Several times since Hoover's era, Republicans of his persuasion have sought the presidency. Senator Robert Taft ran in 1948 and 1952 declaring that "other people simply do not like to be dominated." Representative Ron Paul asserted during his 2012 campaign that Americans "cannot spread our greatness and our goodness through the barrel of a gun." Both were soundly defeated.
Occasionally, a Democrat also breaks from the consensus. Former Vice President Henry Wallace ran for president in 1948 denouncing President Harry Truman's "imperialist policy." Twenty-four years later, Senator George McGovern ran on a promise "to turn away from excessive preoccupation overseas to the rebuilding of our own nation." Like their Republican counterparts, these heretics were painted as unpatriotic and failed at the polls.
In the United States, people who call themselves liberal and those who call themselves conservative share the interventionist impulse. Liberals have good reason. They are by nature teachers and improvers. Conservatives, however, must reject the essence of their creed when they support aggressive foreign policy and the wars that come with it.
The liberal-conservative consensus that shapes our approach to the world embraces both major political parties, most of the press, and the multinational economy. It leads to foreign policy that is not simply interventionist, but utopian, visionary, millennarian. Setting out to remake nations and entire regions, seeking to implant our version of democracy in distant lands, deposing governments and imposing others in their place, springing to the rescue of people we consider oppressed — these are breathtakingly radical projects. They more closely resemble Trotskyism, with its call for "permanent revolution," than conservatism.
Mainstream conservatism has joined the foreign policy consensus. By helping to push the United States into ambitious nation-building projects, its leaders have abandoned their movement's founding principles. A true conservative looks dubiously on foreign intervention. Who does not, is none.
Stephen Kinzer is a senior fellow at the Watson Institute for International Studies at Brown University. Follow him on Twitter @stephenkinzer.