Wednesday, May 07, 2008

Don't believe everything you think

The most common mistakes of homebirth advocates, vaccine rejectionists and advocates of alternative health are mistakes of logic. They assume that what "makes sense" to them is automatically true. Thomas Kida, a professor at the UMass Isenberg School of Management, explains why this assumption is unjustified in his book Don’t Believe Everything You Think: The 6 Basic Mistakes We Make in Thinking.

The 6 mistakes are:

Mistake #1: We prefer stories to statistics. Stories are easy to understand; statistics are hard. The problem is that particular stories which may not be representative while statistics, which are merely the aggregation of thousands or millions of stories, offer a realistic assessment of what typically happens. Homebirth advocacy's striking reliance on birth "stories" shows how homebirth advocates actually embrace and celebrate this mistake.

Mistake #2: We seek to confirm our opinions, not challenge them. Homebirth advocacy is a perfect example of this mistake. To my knowledge, there is not a single homebirth advocacy website or publication that contains accurate information about homebirth. Nonetheless, homebirth advocates actually think that they have done "research" simply because they read the opinions of others who agree with them. In contrast, they generally make no effort to read websites and publications by those who offer information that does not support predetermined conclusions.

Mistake #3: Lay people often do not understand chance and coincidence. Most people have no idea of incidence of various risks. They grossly overestimate the chances of rare events and grossly underestimate the chances of common events. Homebirth advocates grossly overestimate the chances of death from a labor epidural, while simultaneously dramatically underestimating the chance of death from homebirth, which is more than a thousand times higher.

Mistake #4: Our personal perceptions about what is happening are often wrong. Unfortunately, the level of confidence in our perceptions is often entirely unjustified.

Mistake #5: We tend to oversimplify our thinking. Oversimplification is easy; reality is hard. While some simplification is necessary, particularly for lay people when first learning about complicated concepts, we must always keep in mind that simplification introduces distortions. Simplification is the merely the first step in thinking about complicated issues. It does not lead us to correct conclusions.

Mistake #6: Our memories are often inaccurate. This has actually been studied quite extensively. People tend to alter their memories to create a "narrative" that makes sense to them. Reality is not a narrative, however.

These mistakes are a vestige of the thinking processes that served us well in the hundreds of thousands of years of evolution in the wild. Statistics did not exist, so stories were the best way that we had to understand the world around us. Our perceptions were all we had available to us, and oversimplification is almost always the first step to understanding. In other words, there was a time when reasoning from what "makes sense" was the only thing that we had. Now those methods have been superceded by other, more accurate methods, but some people are still stuck in the past.

The typical homebirth advocate, or the typical vaccine rejectionist, does not know about or does not understand the new, more accurate methods for evaluating the world around us. They revert to more "primitive" forms of reasoning because they literally do not know any better.

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