Why do people believe weird things? This question has been fascinating me for years. Clearly, humanity has made and continues to make huge progress. Despite casual appearance, there is a secular decline in the amount of rubbish people believe in. We are going in the right direction. But why so slow? Why aren’t we going faster?
The answer is that there are powerful psychological forces leading people into what the English philosopher Stephen Law unceremoniously calls Believing Bullshit. The strength of these forces is certainly related to education. But even highly educated and very intelligent people can fall prey. Steve Jobs is a fitting example. After being diagnosed with cancer, he refused to be operated and instead
…kept to a strict vegan diet, with large quantities of fresh carrot and fruit juices. To that regimen he added acupuncture, a variety of herbal remedies, and occasionally a few other treatments he found on the Internet or by consulting people around the country, including a psychic. For a while he was under the sway of a doctor who operated a natural healing clinic in Southern California that stressed the use of organic herbs, juice fasts, frequent bowel cleansings, hydrotherapy, and the expression of all negative feelings (Isaacson, p. 454).
How can such a smart man do such a stupid thing? As the psychologist Howard Gardner tells us, intelligence is far from being a one-dimensional faculty, measured by IQ. There isn’t such a thing as Intelligence. Rather, people have Multiple Intelligences. One can be a genius in some dimension and a complete fool in some other.
What interests me in particular is what people do to evaluate evidence. By and large, we are very good at it. Right from the start, we are able to update any prior belief in the light of observation, experience, trial-and-error. This is a basic instinct: we couldn’t get on with life without it. But we can also get badly stuck. A major stumbling block is what psychologists call the Confirmation Bias.
When we use evidence to prove or disprove a hypothesis, there are four possibilities: the evidence can either be present or absent, and the hypothesis can either be true or false.
If we are particularly sensitive about a certain hypothesis – because we wish it to be true, or because much depends on it being true – we concentrate all our attention on True Positives: cases where the evidence is present and the Hypothesis is true. We take a herb, and our ailment is gone. It works! But we fail to take full account of cases where we take the herb and it doesn’t work (False Positives), as well as cases where we don’t use it and the ailment goes away regardless (False Negatives).
This is the Confirmation Bias: disregard of evidence that runs contrary to a tested hypothesis. When properly tested, none of this bullshit alternative medicine works. If you have any doubt, just read here and here. The Confirmation Bias can be a question of life and death.