Carl Sagan was many things — a cosmic sage,voracious readerhopeless romantic, andbrilliant philosopher. But above all, he endures as our era’s greatest patron saint of reason and common sense, a master of the vital balance between skepticism and openness. In The Demon-Haunted World: Science as a Candle in the Dark (public library) — the same indispensable volume that gave us Sagan’s timeless meditation on science and spirituality, published mere months before his death in 1996 — 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.” (Cue in PBS’s Joe Hanson on how to read science news.) But rather than preaching from the ivory tower of self-righteousness, Sagan approaches the subject from the most vulnerable of places — having just lost both of his parents, he reflects on the all too human allure of promises of supernatural reunions in the afterlife, reminding us that falling for such fictions doesn’t make us stupid or bad people, but simply means that we need to equip ourselves with the right tools against them.

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:

The kit is brought out as a matter of course whenever new ideas are offered for consideration. If the new idea survives examination by the tools in our kit, we grant it warm, although tentative, acceptance. If you’re so inclined, if you don’t want to buy baloney even when it’s reassuring to do so, there are precautions that can be taken; there’s a tried-and-true, consumer-tested method.

But the kit, Sagan argues, isn’t merely a tool of science — rather, it contains invaluable tools of healthy skepticism that apply just as elegantly, and just as necessarily, to everyday life. By adopting the kit, we can all shield ourselves against clueless guile and deliberate manipulation. Sagan shares nine of these tools:

  1. Wherever possible there must be independent confirmation of the “facts.”