Washington occasionally gets hit with spasms of second-guessing. We’re seeing that phenomenon at work in this week’s hearings of the so-called 9-11 commission, and in the recent hubbub over a just-published memoir of former White House counterterror chief Richard Clarke.

The hidden assumption in the hearings and Clarke’s book is that someone could and should have prevented the Al Qaeda slaughters of September 11, 2001, and that the someone was Bill Clinton, George Bush, or both.

I’m not buying the thesis, which is profoundly insulting not just to the presidents involved, but to just about everybody working for them. No commander in chief takes delight in watching fellow citizens die, and none would spare any effort to prevent something like September 11. Bill Clinton, for instance, reportedly was preoccupied with Al Qaeda after the World Trade Center bombing in 1993. Unfortunately for him, bureaucratic squabbles — and in some cases, his own indecision — prevented vigorous action against the bad guys.

George W. Bush also tried to take up the Al Qaeda challenge, but discovered that intelligence officers were and are much better at picking up chatter than at picking up secrets. It’s not easy to deal with a small, rabid, and decentralized enemy. Even now, the Department of Homeland Security finds itself issuing vague warnings about unknown potential calamities. That’s about all it can do. Much of the rest depends on vigilance by citizens.

Some partisans in the second-guessing fight clearly want to score political points. Republicans are citing chapter and verse about the Clinton record; Democrats are insinuating that George W. Bush was more interested in getting Saddam than nailing bin Laden. Both sides might just want to put a sock in it: The second-guessing implies that the craft of espionage is perfectible and that a properly financed and trained bunch of spies can prevent any and all bad things plotted by our enemies abroad. This is idiotic.

The worst thing about the recent second-guessing mania is this: It belittles the ongoing war on terror, which is neither distant nor settled. It might make more sense to win that war first, and conduct snarky post-mortems later. After all, aren’t the proponents of the hearings guilty of the thing they say they most want to prevent — taking our attention away from the bad guys, precisely when those very bad guys say they want to strike?