The Science of Fear—titled as such in the US, but known as Risk elsewhere—is a book about risk. Specifically, how terrible we are at judging risk.

As Daniel Gardner summarises on his website:

We are the safest and healthiest human beings who ever lived, and yet irrational fear is growing, with deadly consequences.

To be honest, the U.S title “Science of Fear” doesn’t really capture the essence of the book. The book is more about risk, and it indeed opened my eyes to how bad we are at judging risk.

And because of that, we end up likely to make poor decisions.

That said, here are my notes from the book:

The safety gap is so large, in fact, that planes would still be safer than cars even if the threat of terrorism were unimaginably worse than it actually is: An American professor calculated that even if terrorists were hijacking and crashing one passenger jet a week in the United States, a person who took one flight a month for a year would have only a 1-in-135,000 chance of being killed in a hijacking—a trivial risk compared to the annual 1-in-6,000 odds of being killed in a car crash.

It turned out that the shift from planes to cars in America lasted one year. Then traffic patterns went back to normal. Gigerenzer also found that, exactly as expected, fatalities on American roads soared after September 2001 and settled back to normal levels in September 2002. With these data, Gigerenzer was able to calculate the number of Americans killed in car crashes as a direct result of the switch from planes to cars. It was 1,595.

Fear can be a constructive emotion. When we worry about a risk, we pay more attention to it and take action where warranted. Fear keeps us alive and thriving. It’s no exaggeration to say that our species owes its very existence to fear. But “unreasoning fear” is another matter.

Fear can be a constructive emotion. When we worry about a risk, we pay more attention to it and take action where warranted. Fear keeps us alive and thriving. It’s no exaggeration to say that our species owes its very existence to fear. But “unreasoning fear” is another matter.

But why are we so afraid? That’s the really tough question. Of course terrorism is a real risk. So are climate change, avian flu, breast cancer, child snatchers, and all the other things that have us wringing our collective hands. But humanity has always faced one risk or another. Why should we worry more than previous generations?

We have made enormous advances in human health, but so much more could be done if we tackled them with proven strategies that would cost little compared to the benefits to be reaped. And yet we’re not doing it. We are, however, spending gargantuan sums of money to deal with the risk of terrorism—a risk that, by any measure, is no more than a scuttling beetle next to the elephant of disease. As a direct result of this misallocation of resources, countless lives will be lost for no good reason.

One of the most consistent findings of risk-perception research is that we overestimate the likelihood of being killed by the things that make the evening news and underestimate those that don’t. What makes the evening news? The rare, vivid, and catastrophic killers. Murder, terrorism, fire, and flood. What doesn’t make the news is the routine cause of death that kills one person at a time and doesn’t lend itself to strong emotions and pictures. Diabetes, asthma, heart disease.

It turned out that people’s ratings of the risks and benefits for the ninety activities and technologies on the list were connected. If people thought the risk posed by something was high, they judged the benefit to be low. The reverse was also true. If they thought the benefit was high, the risk was seen as low. In technical terms, this is an “inverse correlation.” It makes absolutely no sense here because there’s no logical reason that something—say, a new prescription drug—can’t be both high risk and high benefit. It’s also true that something can be low risk and low benefit—sitting on the couch watching Sunday afternoon football comes to mind.

Certainty, for example, has been shown to have outsize influence on how we judge probabilities: A change from 100 percent to 95 percent carries far more weight than a decline from 60 percent to 55 percent, while a jump from 0 percent to 5 percent will loom like a giant over a rise from 25 percent to 30 percent. This focus on certainty helps explain our unfortunate tendency to think of safety in black-and-white terms—something is either safe or unsafe—when, in reality, safety is almost always a shade of gray. And all this is true when there’s no fear, anger, or hope involved. Toss in a strong emotion and people can easily become—to use a term coined by Cass Sunstein—“probability blind.” The feeling simply sweeps the numbers away. In a survey, Paul Slovic asked people if they agreed or disagreed that a one-in-10 million lifetime risk of getting cancer from exposure to a chemical was too small to worry about. That’s an incredibly tiny risk—far less than the lifetime risk of being killed by lightning and countless other risks we completely ignore. Still, one-third disagreed; they would worry. That’s probability blindness. The irony is that probability blindness is itself dangerous. It can easily lead people to overreact to risks and do something stupid like abandoning air travel because terrorists hijacked four planes.

Anecdotes aren’t data: That’s a favorite expression of scientists. Anecdotes—stories—may be illuminating in the manner of Shakespeare. They may also alert us to something that needs scientific investigation. The proliferating stories of breast implants causing disease were certainly grounds for concern and aggressive research. But anecdotes don’t prove anything. Only data—properly collected and analyzed—can do that.

When Paul Slovic asked groups of students to indicate, on a scale from 0 to 20, to what degree they would support the purchase of airport safety equipment, he found they expressed much stronger support when told that the equipment could be expected to save 98 percent of 150 lives than when they were told it would save 150 lives. Even saving “85 percent of 150 lives” garnered more support than saving 150 lives. The explanation lies in the lack of feeling we have for the number 150. It’s vaguely good, because it represents people’s lives, but it’s abstract. We can’t picture 150 lives and so we don’t feel 150 lives. We can feel proportions, however. Ninety-eight percent is almost all. It’s a cup filled nearly to overflowing. And so we find saving 98 percent of 150 lives more compelling than saving 150 lives.

Another common failure was illustrated in the stories reporting on a September 2006 announcement by the U.S. Food and Drug Administration that it was requiring the product-information sheet for the Ortho Evra birth-control patch to be updated with a new warning to include the results of a study that found that—in the words of one newspaper article—“women who use the patch were twice as likely to have blood clots in their legs or lungs than those who used oral contraceptives.” In newspapers across North America, even in the New York Times, that was the only information readers got. “Twice the risk” sounds big, but what does it actually mean? If the chance of something horrible happening is one in eight, a doubling of the risk makes it one in four: Red alert! But if the risk of a jet crashing onto my desk were to double, I still wouldn’t be concerned because two times almost-zero is still almost-zero.

An indication of how influential the media can be comes from the most unlikely place. Burkina Faso is a small country in West Africa. It was once a French colony, and French is the dominant language. The French media are widely available, and the local media echo the French media. But Burkina Faso is one of the poorest countries on earth, and threats to life and limb there are very different than in France. So when researchers Daboula Kone and Etienne Mullet got fifty-one residents of the capital city to rate the risk posed by ninety activities and technologies—on a scale from 0 to 100—it would be reasonable to expect the results would be very different than in similar French surveys. They weren’t. “Despite extreme differences in the real risk structure between Burkina Faso and France,” the researchers wrote, “the Burkina Faso inhabitants in this sample responded on the questionnaire in a way which illustrates approximately the same preoccupations as the French respondents and to the same degree.”

Another consistent finding in the research is that the media focus heavily on individual acts and say little about broader contexts and issues. Reporters tell us about the little old lady held up at gunpoint. They don’t tell us how many little old ladies are held up at gunpoint, whether more or fewer are being held up than in the past, who is holding them up and why, or what policies might protect little old ladies. So we should be careful with our terms. The media actually pay very little attention to “crime.” It is “crimes” they can’t get enough of.

But falling crime means fewer crimes are being committed, a trend that cannot be captured by stories of individual crimes because a crime that is not committed is not a story. And so simply because the media focus heavily on crimes while ignoring crime, rising crime will always get more far attention than falling crime.

Of course, nobody knew at the time that September 11, 2001, would be a horribly unique day. There could have been other, equally destructive attacks in the months that followed. Presuming that there had been one attack each month for one full year—with each attack inflicting a death toll equal to that of 9/11—the total number of dead would have been 36,000. This would be horrific but it would still not be a mortal threat to the average American. The chance of being killed in this carnage would be about 0.0127 per cent. That’s roughly one in 7,750. By comparison, the annual risk of dying in a motor-vehicle accident is one in 6,498.

According to the RAND-MIPT terrorism database—the most comprehensive available—there were 10,119 international terrorist incidents worldwide between 1968 and April 2007. Those attacks took the lives of 14,790 people, an average annual worldwide death toll of 379. Clearly, what the world saw that September morning was completely out of line with everything that went before or since. Terrorism is hideous, and every death it inflicts is a tragedy and a crime. But still, 379 deaths worldwide annually is a very small number. In 2003, in the United States alone, 497 people accidentally suffocated in bed; 396 were unintentionally electrocuted; 515 drowned in swimming pools; 347 were killed by police officers. And 16,503 Americans were murdered by garden-variety criminals.

And that 379 figure actually overstates the toll inflicted on Americans, Britons, and other residents of the Western world because most deaths caused by international terrorism happen in distant, tumultuous regions like Kashmir.

In North America, between 1968 and 2007, all international terrorist incidents combined—including 9/11—killed 3,765 people. That is only slightly more than the number of Americans killed while riding a motorcycle in the single year of 2003. In Western Europe, the death toll due to international terrorism between 1968 and April 2007 was 1,233. That is 6 percent of the number of lives believed lost every year in Europe to the naturally occurring radon gas that few people pay the slightest attention to.

The enormity of 9/11 in our consciousness also obscures an important trend. From the 1960s until the early 1990s, the number of international terrorist incidents steadily increased, but when the Soviet Union collapsed, so did terrorism. The peak was reached in 1991, when there were 450 incidents recorded in the RAND-MIPT terrorism database. By 2000, that number had plummeted to 100. In 2000, the trend reversed. By 2004, incidents had soared to 400 a year. But Andrew Mack, the director of the Human Security Centre at the University of British Columbia, which tracks international violence, notes that if you take the Middle East out of the equation, the trend is flat. If South Asia is also taken out, the decline in international terrorism that started at the end of the Cold War actually continued. “That suggests there has been a net decline in terrorism in all regions of the world except the Middle East and South Asia from the early 1990s,” Mack concludes.

In March 2005, ABC News reported it had obtained a secret thirty-two-page FBI report that suggested there was a simple reason that networks of Osama bin Laden’s operatives hadn’t been uncovered in the United States: There may be nothing to uncover.

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