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4.3: Assessing a Source's Credibility

  • Page ID
    21973
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    Our most reliable source of information is our own observations, but when these are not available, then we turn to other sources of information. When we don’t have access ourselves to information about whether a claim is credible, we can look at the source of the claim, at where it’s coming from, at who’s saying we should believe it. Some sources are more credible than others.

    If the claim is not unusual and it comes from someone you have a reason to trust, then go ahead and believe it. If your friend says he ran out of gas in his car last week, then go ahead and believe it. It is not always unwise to accept unsupported claims if they are not extraordinary and nothing much turns on whether you believe it or not. But if he says he met the Prime Minister of England last week and was invited to speak to a session of their Parliament next Monday, then ask for more evidence before you believe this unusual claim very strongly.

    The Weekly World News, The Star, and The National Enquirer, are popular tabloids whose headlines shout out from the racks near the checkout lines of supermarkets and drug stores. Too often they will exaggerate their stories and will print almost anything anybody says, so long as it is entertaining. They will portray the stories as being true without checking whether they are. The editor of the Weekly World News, when asked about the reliability of the stories he prints, admitted this when he said, "Of course we are skeptical about some of the stories, but we wouldn't question ourselves out of a story, particularly when it has no health-related ramifications.'' The editor added, "If we got a fellow who said he was taken aboard a UFO, for instance, we would really see no reason to check it out if it was entertaining, a good story. If we did some probing, we could find out that he'd been in a mental hospital for the past 60 days and then [have to] kill the story." When the reporters locate a person who calls himself or herself an "expert on UFOs," the reporters are not apt to question the person's credentials and will merely report that "experts on these matters have said...."1

    Tabloids are notorious for trying to convince readers by appeal to anecdotes. Anecdotes are reports of individuals’ own experiences. There is nothing wrong with gathering information from individuals, but a few unsystematically acquired anecdotes do not constitute a scientific proof. For example, Lupe says to you, "Forget about seatbelts. They do more harm than good. I was in a car accident once, and the doctor said it was lucky that I wasn't wearing one. If I had been wearing one, I would have been burned up with the car. Instead I was thrown through the windshield and only broke my neck and back." This anecdote may support the generalization that car seatbelts shouldn't be used, but it cannot stand up to statistics showing that, overall, people with seatbelts suffer fewer injuries. It is understandable that you might want to pay more attention to your friend Lupe than to some statistical report from people you do not know, but it is more reasonable to pay attention to the statistics. By the same token, if Lupe had asked her doctor, no doubt the doctor would have said she was lucky not to have had the seatbelt buckled in this special case but that in the future she should buckle up. The doctor's own views about seatbelts will probably have been acquired by paying attention to the statistics, not to the anecdotes of his own few patients.

    Although the "coma woman" headline in the Weekly World News isn't a good enough reason for you to change your beliefs about brain transplanting, the same headline in more reputable publications should cause you to change your beliefs. The same information backed up by a "Yes, it's true" comment from your doctor, also would be a good reason to believe the story.

    Some of our most valuable knowledge is knowledge about which sources are credible sources and which are not.

    Let’s consider a more credible source of information than a grocery store tabloid, namely the president of the United States. How credible is the president when he tells you something? Well, it depends on what he tells you, doesn’t it? If he says Manila in the Philippines has just suffered a 7.0 earthquake, then he’s a very credible source of information. If he says the candidate from the opposition party doesn’t deserve your vote, he is a much less credible source of information.

    Most people think their own observations are a completely reliable source of information. If you saw it, then it’s so, right? Not necessarily. Think about magicians and optical illusions. And then there’s always the problem of faulty memory. When James says he remembers shaking the hand of the president when he was four years old, does the adult James really remember shaking the hand of the president when he was four years old, or does James just remember being told that he did? Sometimes what someone wishes to be true can affect what they observe as when they report observing the Madame at the séance talking to their recently deceased grandmother. Memories can be tricky. Logical reasoners know that there’s always some small possibility that what they remember observing may not be quite as they remember it.

    When you assess a person’s credibility as, say, an expert on tropical medicine, you’ll not want to make this judgment on the basis of whether they are friendly and smile and give you eye contact and a sincere handshake. That’s irrelevant to whether they can speak reliably about tropical medicine, but it’s not irrelevant to whether you want to invite the person to lunch tomorrow. If your local doctor were to say, “She is an expert on tropical medicine,” that would be much more helpful to you than your noticing that she has a copy of The Journal of Tropical Medicine in her hand. Of course, if you were to find out that this copy contained an article written by her, then that would go a long way in telling you she really is an expert and should be trusted when she is speaking about tropical medicine.

    But be cautious. Many TV viewers were convinced by this remark in the commercials: More doctors smoke Camels than any other cigarette." The implicit conclusion is that Camels are safe to smoke.

    Exercise \(\PageIndex{1}\)

    If you wanted to know whether electricity will flow through certain kinds of plastic, who would be the most credible source of information?

    a. A friend of yours who has invented and patented three kinds of plastic toys.
    b. The county librarian who specializes in government documents.
    c. A professional proofreader who has just worked on a new textbook about plastics and electricity.
    d. Your neighbor who is an electrical engineer.
    e. The sales representative of the largest plastics manufacturer in your state.

    Answer

    Answer (d). The electrical engineer would be required to learn this sort of thing as part of his or her professional training. Proofreaders need not know anything about what they are reading. Librarians might be able to find the right book, but they themselves wouldn't necessarily be able to understand the book. The inventor might know about electrical flow in some plastics used in some plug-in toys, but the inventor would look to an electrical engineer for advice.

    Logical reasoners discriminate among sources of information. They trust information from a reputable scientific journal over information from a daily newspaper. They trust the newspaper over their neighbor. Here is a ranking; they trust The New York Times, The Wall Street Journal, The Washington Post, The Los Angeles Times, and perhaps Newsweek magazine, followed by network TV news, the local daily paper, and then local TV stations. They are cautious about believing TV docudramas, political blogs and even their friends’ tweets, and even less so do they trust grocery store tabloids and political leaflets left at their front door.


    1 From Eddie Clontz, Reuters dispatch, reprinted in The Sacramento Bee newspaper, November 26, 1988, p. A2.


    This page titled 4.3: Assessing a Source's Credibility is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by Bradley H. Dowden.

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