Why does the US so often back the bad guys?
Why is it that the United States - forged as a nation in a revolution against tyranny, explicitly dedicated to liberty - has so often found itself backing the bad guys?
Barack Obama has now put himself on the side of democracy
The quandary is not new. Part of the problem is deciding who the bad guys are. One of the founding fathers and the third president, Thomas Jefferson, believed the American Revolution had sparked a fire that would set the world alight.
He was an enthusiast for the French Revolution, defending it even when its nascent democracy descended into dictatorship and terror.
By contrast, his old sparring partner, fellow founding father and the second President, John Adams, was more sceptical from the start and signed a treaty with the country many Americans saw as the foe of liberty: Great Britain.
President Franklin Delano Roosevelt couldn't have been more forthright in his early belief that Hitler was a threat to the whole world. To Churchill's irritation, he demanded that the post-war world should banish the days of empire and colonialism. He didn't live to see it, but the new problem was the clash of new empires.
Belief in universal liberty comes up hard against the real world where policymakers often see the choice as between the bad guys, and the worse guys.
The real problem for the US came with its opposition to the expanding Soviet empire. Communism was a new tyranny, but it cloaked itself in the language of liberty, and attracted those fighting foreign rule and domestic domination. In opposing the Soviet Union and its allies, the USA often found itself in bed with a promiscuous parade of the dodgiest of characters - dictators, torturers and thieves - whose only virtue was not being "Commies".
The US never successfully pulled off the trick of encouraging genuine liberal democracies.
When the Iron Curtain was torn down, the US was definitely on the right side of history but did not seize the opportunity to knock down the bulwarks against communism they no longer needed. Reagan, the first Bush and Clinton did not urge people living in dictatorships in the Middle East and Central Asia to seize the freedoms newly enjoyed in the European east.
Of course, the neo-cons wanted a revolution against this hypocrisy. They wanted the United States to aggressively promote democracy with revolutionary fervour. But in power they targeted old enemies, never old friends. Saddam Hussein and the Taliban were dictators, but in the scale of sin, their enmity weighed more heavily than their tyranny. As jihadists replaced communists as America's favourite existential threat, the old corrupt and undemocratic bulwarks were again seen as better than the alternative.
It is Barack Obama's reaction to this pattern that initially locked his administration into an awkward ambivalence to the Egyptian revolution. He was elected, in part, in reaction to George W Bush's foreign policy.
So on the one hand Mr Obama seems to genuinely believe that it is not the place of the leader of the world's only superpower to pick and choose the leaders of other countries. That is a value consistent with the American Revolution. So is his other instinct, pulling him in the opposite direction. He believes it is the USA's job to promote what he sees as universal values, and he grows more forthright about this day by day.
It will be interesting to see if he follows up with tough conversations with Saudi King Abdullah, Uzbek President Islam Karimov, Ugandan President Yoweri Museveni and other allies who may not share his enthusiasm for the freedoms the president is urging upon Egypt.
For the old dilemma remains. There is some worry in Washington about what follows, and the possibility of the Muslim Brotherhood playing a big role in the future. Many observers warn against building them up into a huge bogeyman. But it is also true that any new Egyptian government that encompasses them would be less friendly to Israel, the peace process and the West in general.
The danger of backing revolution and democracy is that the moral arc of the universe does not always bend towards American foreign policy interests.