Why We Believe

A more common experience is to see patterns in coincidences, something that also represents a hijacking of normal and useful brain function. You think about the girl at the party last Saturday and—bam!—she calls you. You think about the girl who chatted you up in class—and never hear from her. Guess which experience you remember? Thanks to the psychological glitch called confirmatory bias, the mind better recalls events and experiences that validate what we believe than those that refute those beliefs.

But why? Why do we remember the times we thought of someone just before she texted us and forget all the times we had no such premonition? When the mind was evolving, failing to make an association (snakes with rattles are to be avoided) could get you killed, while making a false association (dancing will make it rain) mostly just wasted time, Michael Shermer points out. "We are left with a legacy of false positives," he says. "Hallucinations become ghosts or aliens; knocking noises in an empty house indicate spirits and poltergeists; shadows and lights in a tree become the Virgin Mary."

The brain also evolved to recoil from danger, and the most frequent sources of danger back in the Stone Age were not guns and cars but saber-toothed tigers and other living things. As a result, we are programmed to impute vitality to even inanimate threats, as Bristol's Hood has demonstrated. When he gives a speech about irrational beliefs, he holds up an old cardigan and asks who would be willing to wear it in exchange for about $40. Usually, every hand in the audience shoots up. But when Hood adds that the sweater was once worn by a notorious murderer, almost every hand disappears. "People view evil as something physical, even tangible, and able to infect the sweater" as easily as lice, Hood says. "The idea of spirits and souls appearing in this world becomes more plausible if we believe in general that the nonphysical can transfer over to the physical world. From there it's only a small step to believing that a thunk in an empty house is a footstep."

There is a clear survival advantage to imputing aliveness and asking questions later. That's why, during human evolution, our ancestors developed what is called a hypersensitive agency-detection device, says Benson Saler, professor emeritus of anthropology at Brandeis University. This is an acute sensitivity to the presence of living beings, something we default to when what we perceive could be alive or inanimate. "Whether it's a rock formation or a hungry bear, it's better to assume it's a hungry bear," says Saler. "If you suppose it's a rock formation, and it turns out to be a hungry bear, you're not in business much longer." Defaulting to the "it's alive!" assumption was "of such considerable value that evolution provided us with greater sensitivity to the presence of living agents than we needed," says Saler. "We respond to the slightest hint or indication of agency by assuming there are living things present. Developing ideas about ghosts and spirits is simply a derivative of this hypersensitivity to the possibility" that a living being is present, and too bad if it also produces the occasional (or even frequent) false positives.

The belief that minds are not bound to bodies, and therefore that ghosts and other spirits exist here in the physical world, reflects a deep dualism in the human psyche. No matter how many times neuroscientists assert that the mind has no existence independent of the brain, "we still think of our essence as mental, and of our mind as being independent of body," says Fordham's Guthrie. "Once you've signed on to that, existence after death is really quite natural." This dualism shows up in children as young as 2, says psychologist Paul Bloom of Yale University: kids readily believe that people can exchange bodies, for instance, and since ghosts lack material bodies but have minds and memories, belief in dualism makes them perfectly plausible. At the even more basic level of perception, the brain is wired for faces, says Northwestern's Reinecke. "Even in the first weeks of life, infants tend to perceive angles, contours and shapes that are consistent with faces," he says. There's Mary on the potato chip again.

All of which raises a question. If the brain is wired so as to make belief in the paranormal seemingly inevitable, why are there any skeptics? And not just "any," but more assertive, activist ones. Groups such as the Committee for Skeptical Inquiry, the Skeptics Society and the James Randi Educational Foundation all work to debunk claims of the paranormal. A growing number of scientists and others now proudly wear the badge of "skeptic," just as more scholars are coming out as atheists, like Richard Dawkins did in his 2006 book "The God Delusion" and as Christopher Hitchens did in his 2007 tome "God Is Not Great." The growing numbers and assertiveness of skeptics (and public atheists) reflects the fact that they "have long felt like we belong to a beleaguered minority," says Shermer, who was once a born-again Christian. Their more aggressive attitude provides a sense of mission and community that skeptics, no less than believers, crave. It takes effort to resist the allure of belief, with its promise of fellowship, community and comfort in the face of mortality and a pointless, uncaring universe. There must be compensating rewards.

One such compensation, it is fair to say, is a feeling of intellectual superiority. It is rewarding to look at the vast hordes of believers, conclude that they are idiots and delight in the fact that you aren't. Another is that skeptics believe, or at least hope, that they can achieve at least one thing that believers seek, but without abandoning their principles. Skeptics, no less than believers, think it would be wonderful if we could speak to dead loved ones, or if we ourselves never died. But skeptics instead "seek immortality through our … lasting achievements," Shermer explains. "We, too, hope that our wishes for eternity might be fulfilled." Too bad that as they fight the good fight for rationality, their most powerful opponent is nothing less than the human brain.

With Karen Springen in Chicago and Kurt Soller in New York

© 2008