“The world is better off without Qassem Soleimani.”

That sentence, uttered and tweeted hundreds of times on Thursday night and Friday morning after our military took out the Iranian general, is true. It also invites a follow-up question: Was that benefit worth the cost?

Almost nobody is doing that calculation this morning, because almost no one's head is screwed on straight. The Democratic foreign policy establishment is mostly overwhelmed by either Trump Derangement System or a stubborn attachment to Barack Obama’s more appeasing approach to Iran. This establishment comprises most of the voices you will see on CNN and MSNBC or see quoted in the Washington Post, and all they can do is rage at President Trump’s irresponsibility.

But here’s the thing: Killing Soleimani might really have been irresponsible, even if he was planning an attack on U.S. diplomatic facilities and personnel, as Secretary of State Mike Pompeo states. It’s an open question because we don’t know how Iran will react or how prepared the Trump administration is for those reactions.

And this gets at the other overly simple reaction. A lot of Iran hawks stop their analysis at the first point, that the world is better off without Soleimani, and they get indignant when folks ask if killing him was the right decision. If we’re better off with him dead, how could killing him be a mistake?

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There’s an easy answer to that question: Saddam Hussein and Moammar Qadhafi were murderous, oppressive dictators, but when the United States used force to oust them, leading to their deaths, we didn’t make the world better off.

There’s a conservative principle that should inform us here: Any large, sudden change to a complex system is likely to induce large, unpredictable, and sudden effects, and in general, large, sudden effects are more bad than good.

Soleimani wasn’t simply the chief of a terrorist organization like Abu Bakr al Baghdadi and Osama bin Laden were. He was a high-ranking Iranian official, running a combination terrorist force/foreign policy operation/state department/wannabe-empire. One analyst called him a "viceroy."

We can expect blowback from Iran for our action. Will Iran just attack the U.S. spurring a full-on war? That’s unlikely, but it’s a lot more likely today than it was yesterday, especially since Trump is clearly threatening war.

Will Iran direct an attack against a U.S. ally? If that happens, will we take responsibility and come to the aid and defense of that ally? Doing that would be a hard pill for Trump to swallow given his strong dislike of entangling alliances.

Recall that the U.S. military is currently trying to create some sense of order in Afghanistan and is still doing something in Iraq. These U.S. troops are now targets for Iran, which thanks to Soleimani's actions, has deadly tentacles in these places. My colleague Tom Rogan runs through some possibilities here.

Our editorial today argues that Iran was steadily escalating its violence in the region and that this U.S. act of force might finally halt it. That’s possible.

Dan Shapiro, a sober-minded Obama alumnus, has a thoughtful thread on other possible threats here.

Another unknown: How replaceable is Soleimani? If he’s just a general in a massive nation with a massive military, he can be replaced. Some experts, however, argue that he was uniquely inspiring and capable. In that case, we’ve just hugely weakened Iran’s ability to sow chaos and death beyond its borders. That’s really good.

In addition to all these international threats, there is also the domestic cost: Does this further erode the already worn-down constitutional limits on executive power? The president is the commander in chief, but that doesn’t mean he gets to do whatever he wants. He needs congressional authorization to initiate or enter into hostilities. It’s not clear what justification the Trump administration will offer for this, but it currently looks like it will involve stretching presidential war powers even further than Bill Clinton, George W. Bush, and Obama had already stretched them.

We won’t know the costs for a long time. What we should know now, however, is that just because an evil man is dead, that doesn’t mean that killing him was the right call.