The Baloney Detection Kit – Part 1

Carl Sagan provided us with “Tools for skeptical thinking” through his “Baloney Detection Kit.” Here are some of my favorite excerpts on what to do when evaluating a claim:

Arguments of authority carry little weight – “authorities” have made mistakes in the past. They will do so again in the future. Perhaps a better way to say it is that in science there are no authorities; at most, there are experts

Spin more than one hypothesis. If there’s something to be explained, think of all the different ways in which it could be explained. Then think of tests by which you might systematically disprove each of the alternatives.

Try not to get overly attached to a hypothesis just because it’s yours. It’s only a way station in the pursuit of knowledge. Ask yourself why you like the idea. Compare it fairly with the alternatives. See if you can find reasons for rejecting it. If you don’t, others will.


Occam’s Razor. This convenient rule-of-thumb urges us when faced with two hypotheses that explain the data equally well to choose the simpler.

Always ask whether the hypothesis can be, at least in principle, falsified.

Control experiments are essential.

In part 2: What the Baloney Detection Kit teaches us NOT to do by avoiding common fallacies.

Source: Carl Sagan’s The Demon-Haunted World

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