What is the evidence? (And how do I weigh it?) [Excerpt]

by | Critical Thinking

This is an excerpt from the “Questioning and Critical Thinking” chapter of the 2024 edition of A MORE BEAUTIFUL QUESTION.

A big part of critical thinking is about analyzing and making sense of what’s coming at us—the new information, claims, and viewpoints we encounter.

First, an acknowledgment: Today, it is not easy to vet the information coming at us, because there is so much of it. And as we ask questions about incoming claims and news stories, those questions may not be easy to answer without doing extensive research. But at the very least, we should be aware of the questions; we should ask and answer them as well as we reasonably can. Because we’ve learned by now that the old media gatekeepers are gone (for better or worse) and in the current media landscape, there is no reliable filter to separate good information from bad—except for the filter within each of us, the “built-in baloney detector” that runs on skeptical questions.

A critical thinker presented with a claim—whether it’s coming from a product salesman, a politician, an advertisement, or a news story—habitually asks, What is the evidence behind this claim and how strong is it? That may lead to a subset of more specific evidence questions, such as, Does this evidence come from a biased source? Is there an agenda behind it?

Answering these questions may require digging to find out if, for example, the source of information has a strong track record for telling the truth or whether that source may have a special interest in advancing this particular claim. (In terms of the latter, always ask, Cui bono?—Latin for “Who benefits?”.)

Sometimes the problem with information is not what is there, but what’s missing—whether it’s a news story with insufficient reporting or a sales pitch that leaves out important details. Thus, a critical thinker is inclined to ask, What are they not telling me? when offered potential solutions that may neglect to mention side effects, hidden costs, and potential negative consequences. The good news about this current age of information overload is that it makes it easier than ever before to check up on claims—to do a search on “potential side effects of X” or “hidden costs of Y.” But remember that every counter-claim you find should also be subject to skeptical questions about its veracity.

When someone is trying persuade you of something, be on the lookout for rhetorical “baloney,” as Carl Sagan would put it. Sagan noted that bogus claims and arguments are often rooted in faulty logic. So the question to be asked is: Is this logical? Illogical arguments are not supported by sound reasoning; they tend to be based on fallacies and faulty assumptions. For example, a common fallacy is the slippery slope argument—wherein someone tries to convince you that it is risky to do some perfectly reasonable thing because it will surely lead to something much worse (e.g., one minor restriction will eventually lead to you losing all your rights!).

Sagan pulled together an invaluable list of more than a dozen of the most pernicious logical fallacies to watch out for in his “baloney detection kit,” which is actually an essay first published as a chapter of his 1996 book The Demon-Haunted World: Science as a Candle in the Dark (you can learn more about Sagan’s list of fallacies at www.amorebeautifulquestion.com/Sagan). Once you’re aware of these fallacies, you’ll begin to spot them easily.

Previously we talked about the importance of “considering the opposite” when questioning your own beliefs—and it’s just as important, when evaluating claims or arguments, to again ask, What’s the other side of this issue? But when trying to consider the “other side,” keep in mind that it can also be useful to ask, Is there actually another side? “There is not another side to the question of whether we really landed on the moon,” Daniel Levitin points out. “We did.”

If you decide there is another side of an issue, consider both sides together and ask, Which of the conflicting views has more weight behind it? In the end, you may be left with a judgment call—as in, “I have three strong reasons to believe one side and one reason to believe the other; I’ll go with the stronger case.”

Indeed, being willing to make those judgment calls is an essential part of critical thinking. It can be tempting (particularly in our “low NFC” moments) to say, “There are reasons to choose A and reasons to choose B—so I can’t decide!” Or: “Well, both candidates are flawed—so it doesn’t matter who I vote for.” But the critical thinker will make the effort to compare and carefully weigh the reasons to choose A versus the reasons to choose B—at which point it usually becomes clear that there is a choice that makes more sense.


Read more about the crisis with critical thinking in these stories.


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