Which candidate, Mitt Romney or Barack Obama, would be more likely to go to war against Iran if he wins the presidency in November?

That’s a fair question, and there are at least three good ways of answering it. But first . . . even thinking about the question this way assumes that war (or peace) will be determined not by larger circumstances that any administration would respond to in similar ways. In this case, that may be a fair assumption, but in others it may not be. However, assuming it hinges on the election:

One way of answering is simply to look at the positions each candidate has taken. Presidential commitments made during a campaign tend to constrain presidents once they’re in office, but as Jeffrey Goldberg argues, in this case, the positions are quite similar: Both consider an Iranian nuclear weapon unacceptable. Since both candidates claim to have a hard line against Iran (but, on the other hand, neither is willing to actually commit to war), it’s hard to see much of a difference on that score.

The second method is to approach the issue through partisanship. We’re in an era of partisan presidencies, which means that the president’s personal preferences may not matter as much as the party’s positions. Presidents may not even have much wiggle room when staffing their administration, certainly not in cases in which the party (or at least party elites, or a dominant party group or faction) has a clear position. And partisan personnel may determine partisan policy. Indeed, Dan Larison makes exactly this point: “What isn’t credible is the idea that a Romney administration that will almost certainly be stuffed to the gills with militarists and Iran hawks is going to be less likely to attack Iran than Obama’s.”

There’s a third way of looking at the question, but this method depends in part on whether one shares the conviction that war with Iran would be a very foolish policy. If one believes that, then the evidence is fairly strong that Obama has shown a strong tendency against risky, open-ended military adventurism. When the Obama administration has taken military action — the Libya war, the Afghan surge, the drone war — it’s generally been relatively contained. While no military action is risk-free, Obama hasn’t undertaken anything with the downside risk that war with Iran would entail. That might not preclude nod-and-wink support of an Israeli airstrike, for example, but that’s about it. On the other hand, anyone who believes that some sort of U.S. surgical strike against Iran could be done without much risk at all could find several examples to support the idea that Obama might engage in that kind of attack.

So that’s three different ways of looking at the same question: one having to do with the constraints from campaign promises, one from partisan constraints and one from, basically, skill at the presidency — because a skilled president is good at evaluating clues to what would make viable public policy, whether it’s war overseas or a tax cut or health care reform at home. I think all three are useful, so I’m not really suggesting one or the other as the best bet — but at least as I read them, I think that the evidence overall would suggest that war with Iran is quite a bit more likely from a Romney presidency.