Shadowed by peril as we are, you would think we'd get pretty good at distinguishing the risks likeliest to do us in from the ones that are statistical long shots. But you would be wrong. We agonize over avian flu, which to date has killed precisely no one in the U.S., but have to be cajoled into getting vaccinated for the common flu, which contributes to the deaths of 36,000 Americans each year. We wring our hands over the mad cow pathogen that might be (but almost certainly isn't) in our hamburger and worry far less about the cholesterol that contributes to the heart disease that kills 700,000 of us annually.
We pride ourselves on being the only species that understands the concept of risk, yet we have a confounding habit of worrying about mere possibilities while ignoring probabilities, building barricades against perceived dangers while leaving ourselves exposed to real ones. Six Muslims traveling from a religious conference were thrown off a plane last week in Minneapolis, Minn., even as unscreened cargo continues to stream into ports on both coasts. Shoppers still look askance at a bag of spinach for fear of E. coli bacteria while filling their carts with fat-sodden French fries and salt-crusted nachos. We put filters on faucets, install air ionizers in our homes and lather ourselves with antibacterial soap. "We used to measure contaminants down to the parts per million," says Dan McGinn, a former Capitol Hill staff member and now a private risk consultant. "Now it's parts per billion."
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"There are two systems for analyzing risk: an automatic, intuitive system and a more thoughtful analysis," says Paul Slovic, professor of psychology at the University of Oregon. "Our perception of risk lives largely in our feelings, so most of the time we're operating on system No. 1."
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The same is true for, say, AIDS, which takes you slowly, compared with a heart attack, which can kill you in seconds, despite the fact that heart disease claims nearly 50 times as many Americans than AIDS each year. We also dread catastrophic risks, those that cause the deaths of a lot of people in a single stroke, as opposed to those that kill in a chronic, distributed way. "Terrorism lends itself to excessive reactions because it's vivid and there's an available incident," says Sunstein. "Compare that to climate change, which is gradual and abstract."