by Judith Curry

On this 80th anniversary of Carl Sagan’s birthday.

Brain Pickings has a good post The Baloney Detection Kit: Carl Sagan’s Rules for Bullshit-Busting and Critical Thinking. Subtitle: Necessary cognitive fortification against propaganda, pseudoscience, and general falsehood. Excerpts:

In The Demon-Haunted World: Science as a Candle in the Dark, Sagan shares his secret to upholding the rites of reason, even in the face of society’s most shameless untruths and outrageous propaganda.

In a chapter titled “The Fine Art of Baloney Detection,” Sagan reflects on the many types of deception to which we’re susceptible — from psychics to religious zealotry to paid product endorsements by scientists, which he held in especially low regard, noting that they “betray contempt for the intelligence of their customers” and “introduce an insidious corruption of popular attitudes about scientific objectivity.”

Through their training, scientists are equipped with what Sagan calls a “baloney detection kit” — a set of cognitive tools and techniques that fortify the mind against penetration by falsehoods. Sagan shares nine of these tools:

Wherever possible there must be independent confirmation of the “facts.” Encourage substantive debate on the evidence by knowledgeable proponents of all points of view. Arguments from 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. What survives, the hypothesis that resists disproof in this Darwinian selection among “multiple working hypotheses,” has a much better chance of being the right answer than if you had simply run with the first idea that caught your fancy. Try not to get overly attached to a hypothesis just because it’s yours. 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. Quantify. If whatever it is you’re explaining has some measure, some numerical quantity attached to it, you’ll be much better able to discriminate among competing hypotheses. If there’s a chain of argument, every link in the chain must work (including the premise) — not just most of them. 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. Propositions that are untestable, unfalsifiable are not worth much. Inveterate skeptics must be given the chance to follow your reasoning, to duplicate your experiments and see if they get the same result.

Just as important as learning these helpful tools, however, is unlearning and avoiding the most common pitfalls of common sense. In addition to teaching us what to do when evaluating a claim to knowledge, any good baloney detection kit must also teach us what not to do. He admonishes against the twenty most common and perilous ones — many rooted in our chronic discomfort with ambiguity — with examples of each in action.

Examples include ad hominem, argument from authority, argument from adverse consequences, appeal to ignorance, special pleading, begging the question, etc.

JC reflections

These ‘rules’ are useful commonsense reminders for evaluating any sort of claim. Too often serious baloney detection is ignored by scientists in the interests of careerism and advocacy. Carl Sagan’s birth 80 years ago is a fitting occasion to remind ourselves of these principles.