Why Is Rational Thinking So Hard?

In a recent issue of WIRED, the odd grassroots movement against vaccines gets discussed. The idea that childhood vaccines are bad, is just one more sign that in America, bad science, takes root and flourishes. Science and data rejected because of irrational fears. Apparently though, the anti-rational thinking amongst the human species isn’t a new phenomena:

The rejection of hard-won knowledge is by no means a new phenomenon. In 1905, French mathematician and scientist Henri Poincaré said that the willingness to embrace pseudo-science flourished because people “know how cruel the truth often is, and we wonder whether illusion is not more consoling.” Decades later, the astronomer Carl Sagan reached a similar conclusion: Science loses ground to pseudo-science because the latter seems to offer more comfort. “A great many of these belief systems address real human needs that are not being met by our society,” Sagan wrote of certain Americans’ embrace of reincarnation, channeling, and extraterrestrials. “There are unsatisfied medical needs, spiritual needs, and needs for communion with the rest of the human community.”

Looking back over human history, rationality has been the anomaly. Being rational takes work, education, and a sober determination to avoid making hasty inferences, even when they appear to make perfect sense. Much like infectious diseases themselves — beaten back by decades of effort to vaccinate the populace — the irrational lingers just below the surface, waiting for us to let down our guard.

Before smallpox was eradicated with a vaccine, it killed an estimated 500 million people. And just 60 years ago, polio paralyzed 16,000 Americans every year, while rubella caused birth defects and mental retardation in as many as 20,000 newborns. Measles infected 4 million children, killing 3,000 annually, and a bacterium called Haemophilus influenzae type b caused Hib meningitis in more than 15,000 children, leaving many with permanent brain damage. Infant mortality and abbreviated life spans — now regarded as a third world problem — were a first world reality.

Today, because the looming risk of childhood death is out of sight, it is also largely out of mind, leading a growing number of Americans to worry about what is in fact a much lesser risk: the ill effects of vaccines. If your newborn gets pertussis, for example, there is a 1 percent chance that the baby will die of pulmonary hypertension or other complications. The risk of dying from the pertussis vaccine, by contrast, is practically nonexistent — in fact, no study has linked DTaP (the three-in-one immunization that protects against diphtheria, tetanus, and pertussis) to death in children. Nobody in the pro-vaccine camp asserts that vaccines are risk-free, but the risks are minute in comparison to the alternative.

Still, despite peer-reviewed evidence, many parents ignore the math and agonize about whether to vaccinate. Why? For starters, the human brain has a natural tendency to pattern-match — to ignore the old dictum “correlation does not imply causation” and stubbornly persist in associating proximate phenomena. If two things coexist, the brain often tells us, they must be related. Some parents of autistic children noticed that their child’s condition began to appear shortly after a vaccination. The conclusion: “The vaccine must have caused the autism.” Sounds reasonable, even though, as many scientists have noted, it has long been known that autism and other neurological impairments often become evident at or around the age of 18 to 24 months, which just happens to be the same time children receive multiple vaccinations. Correlation, perhaps. But not causation, as studies have shown.

That lack of understanding causation and correlation is evident in most of the things people complain about in Norwalk. Crime and traffic spring to mind.

Getting the measles is no walk in the park, either — not for you or those who come near you. In 2005, a 17-year-old Indiana girl got infected on a trip to Bucharest, Romania. On the return flight home, she was congested, coughing, and feverish but had no rash. The next day, without realizing she was contagious, she went to a church gathering of 500 people. She was there just a few hours. Of the 500 people present, about 450 had either been vaccinated or had developed a natural immunity. Two people in that group had vaccination failure and got measles. Thirty-two people who had not been vaccinated and therefore had no resistance to measles also got sick. Did the girl encounter each of these people face-to-face in her brief visit to the picnic? No. All you have to do to get the measles is to inhabit the airspace of a contagious person within two hours of them being there.

The frightening implications of this kind of anecdote were illustrated by a 2002 study published in The Journal of Infectious Diseases. Looking at 3,292 cases of measles in the Netherlands, the study found that the risk of contracting the disease was lower if you were completely unvaccinated and living in a highly vaccinated community than if you were completely vaccinated and living in a relatively unvaccinated community. Why? Because vaccines don’t always take. What does that mean? You can’t minimize your individual risk unless your herd, your friends and neighbors, also buy in.

Perceived risk — our changing relationship to it and our increasing intolerance of it — is at the crux of vaccine safety concerns, not to mention related fears of pesticides, genetically modified food, and cloning. Sharon Kaufman, a medical anthropologist at UC San Francisco, observes that our concept of risk has evolved from an external threat that’s out of our control (think: statistical probability of a plane crash) to something that can be managed and controlled if we just make the right decisions (eat less fat and you’ll live longer). Improved diagnostic tests, a change in consumer awareness, an aging society determined to stay youthful — all have contributed to the growing perception that risk (of death, illness, accident) is our responsibility to reduce or eliminate. In the old order, risk management was in the hands of your doctor — or God. Under the new dispensation, it’s all up to you. What are the odds that your child will be autistic? It’s your job to manage them, so get thee to the Internet, and fast.

The WIRED article focuses on vaccination and the anti-vaccination movement. But it’s a good read if your into as one of the Doctors profiled in the piece says, “What I loved about science was its reason. You have data. You stand back and you discuss the strengths and weaknesses of that data. There’s just something very calming about that. You formulate a hypothesis, you establish burdens of proof, you subject your hypothesis to rigorous testing. You’ve got 20 pieces of a 1,000-piece puzzle … It’s beautiful, really.”

source: WIRED, An Epidemic of Fear: How Panicked Parents Skipping Shots Endangers Us All, By Amy Wallace, October 19th, 2009