It's time to scrap failed economic embargo of Cuba. (Commentary).

STUPIDITY, I've heard it said, is defined as continuing to do the same thing, but expecting a different result.

Let's say that you have no idea how it. feels to bash your thumbnail with a hammer. So you do that and discover it to be a tremendously unpleasant sensation.

Now, let's say you bash your thumb again. That's an act of stupidity; you had the information but were unable or unwilling to process it, follow it to its logical conclusion.

Forty years later, the United States' embargo against Cuba feels a lot like that. Through nine U.S. presidencies, Kennedy to Johnson to Nixon to Ford to Carter to Reagan to Bush to Clinton to Bush, we have embraced it as a means of pressuring Fidel Castro's communist dictatorship toward democratic reform. Or toppling it altogether.

If we've made any progress toward either goal, I must have missed it. If there's the scantiest reason to believe change is coming anytime in the near future, I must have missed that, too. Yet we cling to our policy with reflexive stubbornness.

You saw this in the White House response to President Jimmy Carter's historic Tuesday night speech in Havana, where he called for lifting the trade embargo. That call was promptly echoed by a bipartisan group of legislators.

Not going to happen, replied the Bush administration. Said White House spokesman An Fleischer, "The president believes that the trade embargo is a vital part of America's foreign policy."

Excuse me, but... why? On what basis can this belief possibly be sustained?

Certainly, it's difficult to see where the embargo has yielded any strategic benefits for the United States. Lately, even its political benefits are somewhat less than certain. During the Cold War, of course, support for the embargo was a litmus test of sorts. No lawmaker wanted to open him or herself to the charge of being "soft" on communism. It has also been observed that any president or candidate who was less than enthusiastic about the embargo risked alienating a vital voting bloc, South Florida's Cuban exile community.

Not that political expediency justifies failure to do the right thing, but the question is moot in any case. The Cold War is over. And the exile community's support for the embargo is anything but monolithic, as illustrated in a poll, conducted in April. The surve, found that though 61 percent of the exile community want the embargo to continue, 52 percent believe it should no longer be U.S. policy and ought to be replaced by other measures. Perhaps more significantly, nearly half reported sending money to their relatives in Cuba, transactions said to pump as much as $950 million a year into that nation's economy.

So again: Why?

The issue is not whether the Castro regime is a moral monstrosity. It is. But so was South Africa under apartheid. So are China and Saudi Arabia now. Yet somehow, we've found ways to do business with all of them. Indeed, we've used our relationships with those nations to nudge them toward human rights reform.

We've spent 40 years doing the same thing and expecting a different result. Apparently, we're ready to spend 40 more.

Leonard Pitts is a columnist for the Miami Herald.