Presidential primaries always require clarifying fine distinctions between the candidates on issues, since as members of the same party, they share a general ideology and a lot of specific ideas. Which of the Republican candidates hates abortion rights the most, or yearns with more desperate fervor to cut the capital gains tax? It's often hard, if not impossible, to tell. Yet on a few issues, there are meaningful, substantive differences. Now that foreign policy is dominating the campaign debate (at least for the moment), we can get a good look at some actual variation in what the candidates believe.

Back when this race started, Rand Paul was supposed to be the sole outlier among the contenders, the one who had a non-interventionist perspective that was suspicious of traditional Republican bellicosity, particularly when it comes solving problems with the hammer of military force. But with Paul fading toward irrelevance, the most important Republican dissenter is now — prepare yourself — Ted Cruz.

Yes, Ted Cruz, the climate-denying, ObamaCare-loathing, Muslim-excluding Tea Party favorite who is climbing Iowa polls with the support of evangelical voters. When it comes to foreign policy, Cruz sounds dangerously sane. At least for a Republican.

In an interview with Bloomberg News earlier this week, Cruz made clear that unlike most of his primary opponents, he has no interest in putting large numbers of American troops on the ground in Iraq and Syria, either to fight ISIS or Bashar al-Assad's government. "In my view, we have no dog in the fight of the Syrian civil war," he said. "If the Obama administration and the Washington neo-cons succeed in toppling Assad, Syria will be handed over to radical Islamic terrorists. ISIS will rule Syria."

Putting aside the lumping together of the Obama administration with neo-cons (ask Dick Cheney whether he agrees with that), it's a remarkable position for a Republican to take for a number of reasons. On the simplest level, Cruz is accepting limitations to American power. Most other Republicans believe that "strength" is the only measure of whether a foreign policy idea is good or bad. Strength itself is in turn measured by the commitment of American force, and the answer to the question of how much force we should apply is always "more." If Barack Obama wants to wage a bombing campaign, then the better answer must be ground troops. If Obama puts troops on the ground, the better answer is to put more troops in.

Cruz not only rejects that formulation, he even accepts that there could be unintended consequences to American military action. This is something you'd think we'd all have a deep and profound appreciation for after the debacle of the Iraq War, but Republicans have banished the thought from their minds. They continue to insist that if our hearts are pure and our spines are stiff, we can bend anyone to our will, and everything will go exactly as planned.

And Cruz explicitly rejects nation-building, the idea that we can invade someplace, knock out a dictatorship, and then install a government that will birth a flourishing and peaceful democracy in short order. He argues that if we have to use force, we should — but only if it's necessary to protect American interests — and then we ought to get the heck out.

Cruz has been saying this for a while, but it's only now in the wake of the Paris attacks, when his opponents are suddenly advocating sending large numbers of ground troops to Iraq and Syria, that his stance on this issue will be put to the test.

Ordinarily, the question at a time like this is only which candidate can take the general orientation of primary voters and reflect it back to them, but turned up to 11. You think you hate ObamaCare? Let me tell you how much I hate ObamaCare! But Cruz may be hoping he can win over those voters who actually remember what a catastrophe George W. Bush's war was, while at the same time substituting a belligerent attitude for actually belligerent policy ideas.

That attitude is something he's got down pat — he can stir up anti-Muslim paranoia and pour contempt on Barack Obama with the best of them. But if he were president, would he actually make different decisions than someone like Marco Rubio? It's hard to say. One can't know for sure whether Rubio would have the same naïve belief as George W. Bush that democratic values and institutions can be spread through the magical power of invasions. All we have to go on is what they're saying now, and Cruz is one of the only Republican candidates who seems less than eager to repeat the Iraq War all over again.

To be clear, there are still plenty of reasons to be terrified by the prospect of a Ted Cruz presidency. But on the question of what's happening in Iraq and Syria, he's one of the only Republican contenders who seems to have learned anything over the last 12 years.