I had just finished reading a book by the sociologist Duncan Watts when I heard over the weekend that Saif Gaddafi, the son of the former Libyan leader, had been captured and arrested. The book was called Everything Is Obvious When You Know the Answer.
Watts believes that common sense is overrated. That's because we are always trying invent causes for things that happen by chance. We observe the world as it is, and assume things happened for a reason, leaving chance no role. And we are also pretty sure that if we had been astute enough we would have been able to anticipate events much better than we did.
The book seemed appropriate to what happened immediately after the Gaddafi arrest. We had another burst of stories about Tony Blair. The idea, apparently, is that Tony Blair and his government were complicit in the crimes of the Libyan regime because they were involved in a rapprochement with Saif's father. Saif's arrest is, therefore, an embarrassment to the former prime minister.
I have always found this idea very odd. Mr Blair is accused by his critics, which nowadays seems to be almost everybody, of having supported an unnecessary war in Iraq. Instead of taking a cautious and realistic view, he became messianic, they say, attempting to impose his liberalism at the point of a gun.
And now over Libya, the opposite criticism is being made. He is accused of cosying up to an unsavoury regime. Where was his
liberalism, his detractors ask, when he sent friendly letters to Gaddafi and did deals with his regime?
If Mr Blair had known at the outset of the Iraq invasion or at the time of the opening to Libya what he knows now, his policy might have been different. But he didn't. He couldn't have. He was making a practical judgment in each case based on information available to him at the time.
Take Libya. After the Iraq invasion, there was a chance, through diplomacy, to turn a rogue state into one that had more normal relations with the rest of the world, one that stopped backing terrorism and wasn't a nuclear threat.
Liberal internationalists like Mr Blair correctly believe that the only real guarantee of peace is democracy, but at the time there seemed little chance of that in Libya. Working with the Gaddafi regime was a sensible act of statesmanship given the situation at the time.
As it turned out, democracy was nearer than it seemed, but this is only obvious now, as we know the answer. It is very unfair to suggest on this basis that there was something underhand or corrupt about Mr Blair's decision.
If, however, it was merely unfair, I'd leave it there. The problem is that there is something more. Two things more, actually, and both are of importance to supporters of Israel.
The first is the suggestion that liberal interventionists are all hypocrites and the case that they make is a sham. Liberal interventionists say they believe in the power of democracy and use the defence of democracy as an excuse for their intervention. Mr Blair's action is Libya, argues the critics, is proof that the interventionists aren't that bothered with democracy at all.
If this goes unchallenged it makes liberal interventionism impossible. It would make it impossible for anyone to argue that Hamas should be shunned or that Hizbollah is dangerous, or that Israel deserves support as a democratic state.
This is because a degree of realism and a certain amount of hard-headed calculation of how best to deal with a rogue state is necessary. Liberal interventionists must be allowed to be cautious and pragmatic, without being accused of hypocrisy.
This is linked to a second point. Those who accuse Mr Blair of being a warmonger in Iraq and corrupt in Libya make a connection between these two things. They advance a sort of conspiracy theory.
His actions, and those who support himin them, are motivated by the economic interests of the West in oil and the concern to support Israel against the legitimate aspirations of the Palestinians. Thus the West invades where it can and does business deals where it can.
The logic of this theory is hard to follow, but, sadly, that hasn't make it any less potent.