I see many comparisons floating around, here are a few:

Muslim refugees become terrorists at a lower rate than Americans become murderers. And here is Alex on jellybeans.

This article suggests you are more likely to be killed by falling furniture than by a terrorist.

Somewhere in my Twitter feed I saw a claim that an American is more likely to be shot by a toddler than by a terrorist.

By a variety of metrics, European terror attacks were worse in the 1970s and 1980s than today.

Matt Yglesias argues American society is pretty robust to a bunch of people getting shot.

Nonetheless many American (and European) citizens seem to think that a murder by a foreign terrorist is much worse than a murder by a domestic nutcase, and that murder by a foreign terrorist is a major deal, these days at least. What might be the reasons for that view?

1. A murder by a foreign terrorist occasions more fear of future murders. Yet if anything this seems to be the opposite of the case. “Entry” into foreign terrorism in the United States is tightly controlled, and with each murder security procedures are tightened.

2. Foreign terrorists kill us in more painful ways. Seems unlikely, they want to get the job over with.

3. Allowing foreign terrorists to kill us signals to our foreign enemies that we are weak, and worsens our standing in international relations. Our alliances and our deterrents become weaker, to the detriment of global peace.

4. The successes of foreign terrorists increase existential risk, so even a “simple murder” by one of them is fraught with high negative expected value. But note here the difference between inference and causality. A foreign terrorist murder may indicate that a WMD attack is more likely, but does it cause the likelihood of a WMD attack to up? In fact, might it not cause that chance to go down, given tighter security precautions?

#3 and #4 at least possibly make sense. But what’s the actual evidence? Why don’t we spend our time debating #3 and #4? Couldn’t we do event studies on those? Are we willing to reject these hypotheses if the event studies turn up nothing?

And if there is something to #3 and 34, what is the MRS for “death by domestic” vs. “death from a foreign terrorist”? 10 to 1? 100 to 1? Inquiring minds wish to know. In other words, it really may be worse if we are killed by foreigners, but don’t we need to set some parameters on that judgment?

By the way, there is also #5: Due to our heritage as African primates, we are programmed to fear violent attacks by outsiders more than we actually need to today.