unSpun_ Finding Facts in a World of Disinformation - Brooks Jackson [53]
• Does the source have the requisite skill? A trained epidemiologist should be trusted more than a newspaper headline writer to evaluate whether a cluster of cancer cases was caused by something in the water, or was just a statistical fluke.
• Have the results been replicated, or contradicted? Sometimes one study tells a story that isn’t backed up by later research. Have the results been repeated in similar studies? Do other researchers agree, or do they come up with contrary findings? The Cold-Eeze story shows how cherry-picked studies can mislead us.
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The lesson here is that somebody who is an authority in one field isn’t necessarily qualified in another. Sam Waterston plays a smart, tough prosecutor on television’s Law & Order series, but so far as we know he has no special expertise as a financial adviser. So why should we give any special weight to his TV commercials praising the brokerage firm TD Waterhouse? Bruce Willis endorsed President George H. W. Bush in 1992 and supported the current war in Iraq, but his portrayal of action heroes on the screen is no reason to give his political or military views any more weight than your next-door neighbor’s. The same goes for Martin Sheen’s endorsement of Howard Dean in the 2004 Democratic presidential primary. Playing a president on TV is about as valid a qualification for making political judgments as playing a doctor on TV might be in recommending decaffeinated coffee, the way Robert Young did in the 1970s, after starring in Marcus Welby, MD on television.
Before relying on any authority, ask yourself, “Is this source competent? Does he know what he’s talking about? Does she have any real evidence? Do other authorities in the same field agree?”
APPEALS TO POPULARITY
Advertisers use these all the time. A typical example: a hospital in Saginaw, Michigan, says it is “preferred two to one.” Does having a large number of patients mean that a hospital provides the best care? Not necessarily. It might simply have better parking or be located more conveniently.
Other examples to look out for: “top-selling”; “number one”; “preferred over…” In politics the “front runner” is often the candidate to watch, but is not necessarily the best one or even the one destined to win, as onetime front runner Howard Dean discovered in the 2004 Democratic primary races. And in February 2006, both Ford and General Motors were claiming to be the top-selling brand of automobiles in the United States, as figures on 2005 vehicle registrations trickled in. In fact, both automakers had been losing ground for years, falling from a combined 60 percent of the U.S. market in 1986 to about 45 percent in 2005. Each might just as easily have said it was “preferred by fewer and fewer.”
Popularity may settle elections, but it doesn’t settle questions of fact. Ask yourself, “Is this thing popular because it’s good, or for some other reason, such as a big advertising budget?”
FAULTY LOGIC
Whole books and several websites have been devoted to the question of logical fallacies. One that trips up many people is the idea that when two events happen, the first one has caused the second. In Latin, this is called the post hoc, ergo propter hoc fallacy, meaning “after this, therefore because of this.”
The post hoc fallacy is seductive because of what we observe to be true in our daily lives. We step on the car’s accelerator; the car moves forward. We flip on a light switch; the light comes on. We touch a lit match to kindling; the kindling catches fire. We may be disappointed, however, if we assume that the shirt we put on before a successful fishing trip is therefore a “lucky” shirt that will magically produce fish the next time. That’s just superstition. When