• In his influential book, “Science as a Candle in the Dark,” Carl Sagan wrote about how susceptible humans are to being deceived, and how healthy skepticism can inoculate us against those deceptive tactics.
• Using lessons from the training that scientists go through, he devised a “baloney detection kit,” which contains 9 lessons that everyone can apply to just about any situation they encounter.
• Are you being deceived? Is someone attempting to deceive you? How can you tell? And should you pay attention to what they’re saying, or be critical of it? These 9 tools are more relevant than ever.

1.) Demand independent confirmation of whatever statements are asserted as facts.

2.) Encourage substantive debate from all points of view by those with substantial, relevant expertise.

3.) Don’t accept an argument from an authority because that person is an authority. Instead, judge arguments based on the merits of the underlying facts, and how experts scrupulously interpret those facts.

4.) Spin as many hypotheses as you can that are consistent with the data. Every possible explanation that isn’t ruled out or contradicted by the already-existing data should be considered, and each hypothesis should be tested and examined as rigorously as possible.

5.) Whatever your favorite, most preferred hypothesis is — especially if it’s your original idea — be its harshest critic. By attempting to knock it down or poke holes in it as hard as you can, you’ll determine how well it stands up under the steeliest of scrutiny. (And if you don’t, others will.)

6.) Don’t settle for a qualitative analysis of the issue. Be quantitative: ask and answer the key question of “by how much?”

7.) If there’s a chain of argument being put forth, then every link in the chain, from the premise to the final conclusion, must be sound.

8.) The convenient rule of Occam’s Razor: to choose the simplest explanation among multiple hypotheses that explain the data equally well.

9.) Ask whether the hypothesis, at least in principle, can be falsified. Non-falsifiable and untestable hypotheses cannot be checked out, and hence those ideas are incapable of disproof.

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