Case 6: Seeing what he wanted to see


This post is number six in my series looking at cases where it seems that “believing we are right” has led to bad outcomes, sometimes even spectacularly bad results, for leaders, teams and organizations.

For my upcoming book, Big Decisions: Why we make decisions that matter so poorly. How we can make them better, I have identified and categorized nearly 350 mental traps and errors that lead us into making bad decisions. The many high-profile situations that I have examined demonstrate the bad outcomes that can be produced by mental traps and errors. My premise is that, at the least, if we recognize and admit that we don’t know the answer, we will put more effort into looking for better decision options and limiting the risks stemming from failure when making important decisions.

In this case, expectations from limited evidence led a brilliant scientist astray.


Galileo stubbornly believed that Saturn was three planets in close orbit.

This belief, which the Italian astronomer clung to until he died, belied what otherwise was his use of the scientific method: Other astronomers with stronger telescopes reported that what he saw as multiple planets was instead one planet with previously unknown rings around it.

These traps and errors may have clouded Galileo’s vision:

  • Galileo, it seems, was among the first scientists to fall prey to Experimenter’s Bias (experimenters’ tendency to only put credence in cases that support the results they expect). He saw what he wanted to see and discounted evidence that he was wrong.
  • The idea of rings around a planet was unknown to Galileo. He was led astray by the Representativeness Heuristic (judging the likelihood of an occurrence by matching it with a category or past circumstance, causing errors when the category or circumstance does not fit).. What he knew from his observations were planets.
  • Having viewed only a few planets through his telescopes, Galileo used only a very small sample of observations to draw his “three planets” conclusion about Saturn. He made a Faulty Generalization (drawing a conclusion about all or many instances of a phenomenon reached based one or just a few instances of that phenomenon).

To understand a situation, our typical response is to merge what we have previously experienced with whatever evidence is at hand. This shortcut usually works, but when what happened in the past and the current evidence are not representative, our conclusion can be dead wrong.