Peter Beinart noticed that Bernie Sanders wasn’t very well-prepared to talk about foreign policy last week, and explains why he thinks he needs to improve:

If Sanders could challenge Hillary more convincingly on foreign policy, he’d air an important debate about how much of a threat events in Syria and Iraq pose to the United States—and whether further American military intervention will stabilize the Middle East, or further destabilize it. He’d also be the one major candidate in either party challenging the pervasive, and to my mind untrue, narrative that under Obama, America’s retreat has sparked chaos around the world.

Between now and the next debate, let’s hope he studies more.

I agree that it would be desirable for Clinton’s challengers to force a serious debate on foreign policy, but that depends on whether any of them understands how to do that. Based on what we saw in Tuesday’s debate, they don’t. That’s why the debate seemed so dispiriting for those of us that were specifically hoping that Clinton would face a strong challenge to her record on these issues. Three of the challengers on the stage didn’t really know how to do that, and the one who could have spent a lot of time trying to out-hawk Clinton. Webb’s outing was uneven at best, and he spent much of the limited time he had to complain about the nuclear deal that Clinton and most Democrats support.

Sanders sounded like a candidate who knew there were certain positions he had to reject, but beyond that it got a bit vague. That’s why he ruled out ground troops in Syria when no one brought it up and declared that he wasn’t a pacifist when no one suspected that he was one. Instead of putting Clinton on the defensive, which Sanders seems disinclined to do anyway, he was the one who seemed to be preemptively defending himself against charges of “weakness” by talking about the different wars he supported. This had the effect of further blurring the differences between him and Clinton.

One reason he didn’t do very well on these questions last week is that Sanders genuinely seems uninterested in foreign policy, and so he hasn’t made it a major part of his presidential campaign. Another is that he correctly judges that most Democratic voters would rather hear him talk about domestic issues, so he has had little incentive to spend time either “studying” or talking about these things. Maybe Sanders assumes that any progressives that want to hear an antiwar message are already with him because of his other positions, and those that aren’t yet with him don’t care about hearing an antiwar message.

Then again, if you listened to Sanders last week you wouldn’t have heard many antiwar arguments except for his correct opposition to a “no-fly zone” in Syria. Along the way, Sanders endorsed the administration’s war on ISIS and its overall Syria policy. I suppose that is the politically safe option in this contest, but it doesn’t make much sense if one wants to draw a sharp contrast with the always-hawkish Clinton. There can’t be much of an “important debate about how much of a threat events in Syria and Iraq pose to the United States” in the Democratic primaries when the big left-wing insurgent buys into the idea that the U.S. should be waging an illegal war in Syria and Iraq.

The suggestion that Sanders “studies more” before the next debate creates the impression that Sanders is going to remedy the problem Beinart identifies in just a few weeks. It is doubtful that more debate prep will do the trick, because a candidate without much interest in these issues isn’t going to make the time and may not even have the time to “study” as much as is needed. The bigger problem is that Sanders doesn’t seem to want to make the necessary case against Clinton’s poor foreign policy judgment. Even if Sanders gave more polished answers, Clinton would still emerge unscathed because he is leery of attacking her for past errors. Sanders declared the Iraq war “the worst foreign policy blunder in the history of this country,” but left it for the audience to work out that Clinton supported that blunder. Clinton has a well-established pattern of taking the hawkish side in every major foreign policy debate, but Sanders seems unwilling to point it out. The other challengers that might be willing to do so can’t get any traction for other reasons, and that leaves us with a pretty anemic foreign policy debate on the Democratic side.