SelectionEffects

 

"Putting oneself into other people's shoes" is a cliché not often practiced in real life. We all have a natural tendency to assume that our own situation is typical — that most other folks are roughly like us in upbringing, in wealth, in age, in goals, and in patterns of thought. This is, obviously, wrong ... but we know ourselves so well that it is a natural mistake to make. It is particularly noticeable to us when other people make it — when the well-to-do, for instance, are puzzled by the fact that everyone does not share their troubles or opportunities, and naively express this. "Let them eat cake" is a famous example of this mistake, along with "The Law, in its majestic impartiality, forbids both the rich and the poor from sleeping under bridges."

But more generally, the failure to put ourselves into others' shoes is a special case of a whole family of fallacies based on what astronomers call "selection effects". We do not observe a random sample of the universe; bright stars can be seen from farther away than dim ones. If we simplemindedly count stars, we may come to think that there is a growing surplus of bright stars the farther off we look. Apparently we are in a neighborhood of unusually faint objects compared to the rest of the universe. (The same holds for galaxies on cosmic scales.)

How obvious a fallacy, we may say — but how often do we ourselves fall prey to this in our daily lives? We think that the people and events we read about in the newspaper are typical of society — whereas they are in fact selected for their newsworthiness. So they are anything but representative! We commonly have an exaggerated fear of big, dramatic kinds of accidents — airplane crashes, mass murders, explosions, etc. We hear about them because they're "news". We overestimate their probability far beyond their actual rate of occurrence; we conversely underestimate the chance of much more common but more isolated events such as household accidents, death or illness from smoking or overeating, and the like.

We remember extraordinary happenings, however rare, and tend to give them more weight than they deserve. A conscious appreciation of selection effects can help us avoid such fallacious thinking.

Tuesday, May 11, 1999 at 05:56:55 (EDT) = 1999-05-11

TopicScience - TopicLife


(correlates: SmallNumberIllusions, OurLimitedExperience, RightAndLevel, ...)