Many “hard” scientists regard the term “social science” as an oxymoron. Science means hypotheses you can test, and prove or disprove. Social science is little more than observation putting on airs. Among the social sciences, economists are the snobs. Economics, with its numbers and graphs and curves, at least has the coloration and paraphernalia of a hard science. It’s not just putting on sandals and trekking out to take notes on some tribe.

Political science, meanwhile, announces its defensiveness in its name. If it really were a science, it wouldn’t need to say so quite as adamantly, would it? The difficulty with social science is that it’s about people, who tend to be fickle. Political science is usually about people in large groups. Parties. Societies. Nations. If you want to test a proposition about, say, the relationship between democracy and free trade, you can’t just set up a bunch of countries to experiment with. You have to take what you find, and there will always be some exception or complication to defeat your pretensions to science.

For the past four decades, however, we have been conducting something pretty close to a scientific experiment on one of the most important practical questions the world has ever faced. This question has dominated American politics, off and on, for almost a century. We have conducted this experiment at no small cost and have ruthlessly ignored the results. The question is: What is the best way for free nations to defeat totalitarian regimes in general and communism in particular?

Communism was never a monolith. Even in its heyday, it came in lots of flavors. There was Tito’s Yugoslavia, which always kept a foot outside the Iron Curtain and turned out to be 150 or so countries united only in their loathing of one another. There was China, the subject of Americans’ most paranoid Cold War fantasies and now the subject of paranoia of exactly the opposite sort. There was Albania, a black hole from which no information could escape. There was the romantic Latin flavor that was more about the revolution itself than about nationalizing the means of production.

And from 1917, when Russia went communist, to 1989, when the Berlin Wall came down, the United States tried almost every conceivable variety of policies toward these various styles of communist nations. Sometimes we were hostile; sometimes we were friendly. We had summits, we had boycotts. We launched secret wars in Latin America, made secret visits to China, tore apart our own society through wars in Vietnam and Cambodia that can still break up a dinner party. (It’s like arguing about the Civil War in 1905.)

To this day, there is one communist country toward which American policy has been unrelentingly hostile. One communist government with which we have never even attempted detente. One communist country that we invaded without even a fig leaf of an invitation from a legitimate government. One communist country where we have never tried the seductive power of capitalism and instead have maintained a total trade embargo. And now, 20 years after communism collapsed almost everyplace else, in this same country a communist government survives unreformed and unapologetic.

If any conclusion can be drawn with scientific certainty about any question in the field of political science (or maybe it belongs to “international relations,” an even fuzzier academic subdivision), it surely is that the United States’ Cuba policy has not worked. Can anyone defend it? In recent years, the closest thing to a defense has been, “Wait, wait, just a bit longer! He’s almost gone.” Well now he — Fidel — is gone, more or less. And nothing has changed, except that our embargo makes us look more ridiculous and powerless than ever. The small changes President Obama announced last week will help. But abandoning the embargo as a proven failure would help more.

Of course communism is doomed in Cuba, and probably soon. Already the days when Cuban troops were making trouble and Cuba was enjoying billions of rubles in subsidies from the Soviet Union are a distant memory. But why wait? Our Cuba policy is held hostage by a zealous ethnic minority (actually a small minority of a minority) that makes the Israel lobby look as cuddly and unthreatening as the president’s new puppy.

As many have pointed out, we won the Vietnam War in a way. Two ways, in fact. Vietnamese fleeing communism have been a great new ingredient in our ethnic stew, and meanwhile Vietnam is embracing capitalism as hard as it can. We’ve already been enriched by the energies of Cubans who have arrived here since Castro’s revolution. So why do we continue to deny the Cubans still stuck on Castro’s Island the opportunity to enjoy the fruits of capitalism as well?