Humans, doctors and grad students included, are all prone to rationalization. This can be a good thing. Think about that TV show House, M.D.. The main character is not always right, but he always is totally convinced of his own opinions. If you think about that, it’s pretty remarkable.

When his opinions are refuted by hard evidence, he drops them without remorse. But up to that point, he is sufficiently certain to risk your life on the basis of his conviction. That’s actually a pretty good thing, in the following sense: if he were unwilling to change his opinion after finding new evidence, he would be an extremely dangerous person to have as a physician. By a similar token, if he wanted conclusive proof of a given diagnosis before starting treatment, he would lose patients because they would die before he was certain.

The following formula is reasonable: get the information you can and act decisively on that until better information is available. But it’s only reasonable so long as you keep the information channels open. That’s why Dr. House is a good role model. Despite being a jerk and despite seldom acknowledging that he was wrong, he never persists in a wrong opinion once it’s disproven.

The problem is that we are prone to rationalize the facts based on the diagnosis we had before. Take people who still believe that Saddam Heussein was involved in the September 11 attack. Presented with new evidence, many people will choose to ignore or rationalize around that evidence in order to preserve their old, erroneous conclusion.

And with just a few simple, mental sleights-of-hand, we can preserve that belief. Here’s another fine example: form the NYT, an Iraqi official purchased several million dollars worth of totally useless “electrostatic magnetic ion attraction” detectors that are billed by the manufacturer as being able to detect bombs and ammunition. A few simple tests are sufficient to show that they are capable of no such thing.

Why would someone believe something patently false in light of clear data to the contrary? Before we get all proud about how we are different from them, those other people, I would offer the following words of caution: believing that we are right is seductive to all of us. The only shared standard against which anyone can test his opinions is the physical world and the data that comes from it and that’s not an easy standard to uphold.

Cheers,
Peter