WHEN you’ve been wrong about something as important as war, as I have, you owe yourself some hard thinking about how to avoid repeating the mistake. And if that’s true for a mere kibitzing columnist, it’s immeasurably more true for those in a position to actually start a war. 

So here we are, finally, messily winding down the long war in Afghanistan and simultaneously being goaded toward new military ventures against the regimes in Syria and Iran. Being in the question-asking business, I’ve been pondering this: What are the right questions the president should ask — and we as his employers should ask — when deciding whether going to war is (a) justified and (b) worth it? Here are five, plus two caveats, and some thoughts about how all this applies to the wars before us.