Here’s an excellent article by Dr. Harriet Hall, with a long-ish preamble, which should be required reading for anybody who has a friend say “My chiropractor/acupuncturist/homeopath/witch doctor made me feel better.”
I’m going to extensively quote her eight points on why people often believe something helps them that has perhaps actually done them harm. Do read her whole article, especially if you are not scientifically inclined. She wrote the article for a lay readership.
- The disease may have run its natural course. A lot of diseases are self-limiting; the body’s natural healing processes restore people to health after a time. A cold usually goes away in a week or so. To find out if a cold remedy works, you have to keep records of successes and failures for a large enough number of patients to find out if they really get well faster with the remedy than without it.
- Many diseases are cyclical. The symptoms of any disease fluctuate over time. We all know people with arthritis have bad days and good days. The pain gets worse for a while, then it gets better for a while. If you use a remedy when the pain is bad, it was probably about to start getting better anyway, so the remedy gets credit it doesn’t deserve.
- We are all suggestible. If we’re told something is going to hurt, it’s more likely to hurt. If we’re told something is going to make it better, it probably will. We all know this: that’s why we kiss our children’s scrapes and bruises. Anything that distracts us from thinking about our symptoms is likely to help. In scientific studies that compare a real treatment to a placebo sugar pill, an average of 35% of people say they feel better after taking the sugar pill. The real treatment has to do better than that if we’re going to believe it’s really effective.
- There may have been two treatments and the wrong one got the credit. If your doctor gave you a pill and you also took a home remedy, you may give the credit to the home remedy. Or maybe something else changed in your life at the same time that helped treat the illness and that was the real reason you got better.
- The original diagnosis or prognosis may have been incorrect. Lots of people have supposedly been cured of cancer who never actually had cancer. Doctors who tell a patient he only has 6 months to live are only guessing and can guess wrong. The best they can do is say the average patient with that condition lives 6 months – but average means half of people live longer than that.
- Temporary mood improvement can be confused with cure. If a practitioner makes you feel optimistic and hopeful, you may think you feel better when the disease is really unchanged.
- Psychological needs can affect our behavior and our perceptions. When someone wants to believe badly enough, he can convince himself he has been helped. People have been known to deny the facts – to refuse to see that the tumor is still getting bigger. If they have invested time and money, they don’t want to admit it was wasted. We see what we want to see; we remember things the way we wish they had happened. When a doctor is sincerely trying to help a patient, the patient feels a sort of social obligation to please the doctor by improving.
- We confuse correlation with causation. Just because an effect follows an action, that doesn’t necessarily mean the action caused the effect. When the rooster crows and then the sun comes up, we realize it’s not the crowing that made the sun come up. But when we take a pill and then we feel better, we assume it was the pill that made us feel better. We don’t stop to think that we might have felt better for some other reason. We jump to conclusions like the man who trained a flea to dance when it heard music, then cut the flea’s legs off one by one until it could no longer dance and concluded that the flea’s organ of hearing must be in its legs!
After you read that, check out Val Jones’ article on why false positives are so common in science. Scientists, you see, are those who know that the one we fool is most often ourselves.