
By Dan Gardner, The Ottawa Citizen
Ideas come from a lot of places, and some of them are better than others. Is the patient sick? Stick some leeches on him to suck out the bad blood.
That made sense to somebody, so they did it, and the patient felt better. It must have worked. Others tried it and sometimes the patient felt better, sometimes worse, which meant, naturally, that while the treatment didn't always work, it sometimes did, which is good. So more and more people did it, and pretty soon there were so many people sticking leeches on sick people it seemed obvious the treatment worked because they couldn't all be wrong.
Nobody asked if maybe they were mistaking correlation for causation, or there was a placebo effect at work, or popularity isn't evidence of efficacy. They just kept sticking leeches on sick people. And when they had been doing it as long as anyone could remember, they kept on doing it because, well, that's what they had done for as long as anyone could remember.
Needless to say, this is not a good way to develop medical treatments and we don't do it this way anymore. Now, we insist on proper scientific testing. But we do continue to use countless traditional treatments that were developed the old-fashioned way, which is why diligent medical researchers subject these treatments to proper scientific testing and encourage doctors to stop doing what they've always done if, in fact, it doesn't work. That's evidence-based medicine.