During the Second Intifada in Israel in 2000, one way Palestinian militants lashed out against Israelis was by blowing themselves up on public buses. Tourism to Israel slowed to a trickle during this tense time, so two economists wondered whether that meant Israelis would stop riding buses, as well.

Instead, they found that sales of multiple-ride tickets and monthly bus passes were unaffected. Even single-ride passengers who were frequent users of the system didn’t change their habits. Those Israelis who lacked viable options for getting around, it seemed, simply made their peace with the slightly elevated chance that their bus would explode, and got on. It was only among car owners that sales of bus tickets declined.

“People can learn to control their emotions, and economic incentives affect the degree to which individuals do so,” wrote the authors of that study, Gary Becker and Yona Rubinstein. Given powerful enough incentives, they explain, people will choose to control their fear.

The U.S. faces its own terror threat—predominantly from homegrown fanatics. An analysis by the New America think tank earlier this year found that since September 11, nearly twice as many Americans have been killed by non-Muslim extremists as by Islamist radicals. Robert Dear, the man accused of killing three people at a Planned Parenthood in Colorado Springs last week, appears to be one of these domestic terrorists.

Though authorities have not offered a definitive account of Dear’s motive, he mentioned “no more baby parts” to law-enforcement officials after his surrender, and at least one acquaintance said he praised people who attacked abortion providers as doing “God’s work,” according to the The New York Times.

Attacks meant to intimidate abortion providers and clinics have become a tragically common element of the American abortion battle. The first abortion provider to be murdered was David Gunn, in 1993, and perhaps the most infamous recent slaying was that of George Tiller, who was shot in the head as he served as an usher at his church in 2009. Overall, anti-abortion violence has killed 11 people, and that’s not counting dozens more bombings, attempted murders, and even acid attacks tracked by the National Abortion Federation.


Abortion Clinic Violence Incidents by Year (1976-2005)

NBER

There’s been an uptick in threats against reproductive health-care facilities since this summer, when the Center for Medical Progress, a pro-life organization, began releasing videos showing Planned Parenthood officials discussing fetal tissue.

“It is likely criminal or suspicious incidents will continue to be directed against reproductive health-care providers, their staff, and facilities,” an FBI Intelligence Assessment warned in September, according to CBS News. Last week, that nightmare came true.

Anti-abortion terrorism, like all terrorism, spreads fear among far more people than it kills. (This is, alas, the point of terrorism.) Very few people will actually be gunned down on a Tunisian beach, but tourism there is plummeting anyway. Similarly, for people who attack abortion clinics, sowing fear is part of the plan.

But does it work? Attacks on abortion clinics are ghastly and take a harsh toll on the communities where they occur—but do they actually discourage abortion?

Anti-abortion violence actually peaked in the 1990s, and that era also saw a decline in both abortions and abortion providers. In 1993, the year before President Clinton signed a law prohibiting anyone from forcibly obstructing abortion clinics, 50 percent of clinics reported being the targets of violence and harassment.

When the economists Mireille Jacobson and Heather Royer examined whether these attacks were actually reducing the demand for or supply of abortions, they found that the effect was modest. In targeted areas, an attack on a clinic typically reduced the number of providers in the area by 6 to 9 percent, and the number of abortions by 8 to 9 percent. (The impact was felt more severely outside of hospitals: Clinic-based abortions and providers dropped by 10 to 14 percent.) When a murder happened, the effect was even more pronounced. Both abortions and providers decreased ten-fold, and they stayed at that level for years.

But there was a twist in their data. You’d think that dip in abortions would be matched by a comparable rise in births—but it wasn’t. Within a year after an attack, births in the targeted area only went up by about 1 percent, far less than the amount abortions decreased. The reason? Abortion rates in neighboring counties ticked up. The women simply went elsewhere for their services.

“These findings indicate that the primary effect of anti-abortion violence is a change in the location of abortions,” the authors write. Like the Israeli bus passengers, the abortion-seeking women saw few options other than to face their fears and get the procedure done anyway.

Of course, this doesn’t mean that intimidation by anti-abortion groups can’t rattle patients and alter the course of their decisions. In 2000, another study found that more mundane, yet non-lethal, anti-abortion activities—things like picketing, vandalism, and physically blocking patients—have a big effect on the abortion rate. Not only have these activities cut the number of abortions by about a fifth, they have also increased the price of the procedure. In 2011, the vast majority—84 percent—of abortion providers said they experienced harassment, a category that included picketing, according to the Guttmacher Institute. Other studies of women who encountered protesters on their way into an abortion clinic found that 16 percent or so were “extremely” upset by them.

And eliminating facilities altogether, when there are no proximate alternatives, can have an equally dramatic impact. After Texas enacted a law in 2013 that shuttered roughly half of the state’s abortion clinics, abortions there declined by 13 percent.

“Given that big acts usually only target one facility, women interested in seeking an abortion often have the ability to go somewhere else nearby,” Heather Royer said in an email. “But legislation like the [Texas] TRAP laws affect entire areas, essentially affecting the whole abortion market.”

Wide-scale harassment and steep obstacles, especially across an entire region or state, can coerce abortion-seeking patients into giving up. Or at least, the hurdles can make the procedure so inconvenient as to be practically impossible.

When it comes to abortion, meanwhile, terrorism doesn’t pay. Deadly attacks on isolated clinics don’t scare away abortion patients if they are truly determined to get the procedure. Violence is often called “senseless,” but in the case of violent attacks on health clinics, it literally is: It doesn’t even serve the deranged goals of the attacker.