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4.2: When Should You Accept Unusual Statements?

  • Page ID
    21972
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    We all know that observations are not infallible. In ancient Egypt at the time of the pharaohs and their pyramids, a group of magicians would walk into the marketplace and begin displaying their powers. The lead magician would hold up a walking stick that had been carved in the shape of a snake and pass it around the audience. Soon after getting it back, the magician would hold up the stick, call on the supernatural powers of the Egyptian gods, and throw the stick on the ground. There the stick would turn into a live snake and crawl away into the crowd, leaving the audience stunned and even more in awe of the power of the pharaoh and his magicians.

    Did the stick really turn into a snake? "No, that's impossible," you are apt to say, "because it's got to be a trick." That is right. Unknown to most people, there is a certain Egyptian snake that can be temporarily paralyzed by applying well-placed pressure to the back of its neck. A physical shock to its head can un-paralyze it. The lead magician's stick looked like this snake. After the stick had been passed around and while other magicians were performing other tricks, the lead magician switched sticks with a magician who had been carrying the paralyzed snake. When the lead magician threw the snake down head first, it woke up and crawled away—naturally, not supernaturally.

    The magician's audience accepted the performance as a straightforward demonstration of the powers of magic and the supernatural. The typical Egyptian did not approach the demonstration with the critical attitude of the modern logical reasoner. Instead, he or she was more gullible and already predisposed to accept supernatural explanations for surprising phenomena. A logical reasoner such as yourself would demand better evidence before accepting the magician's explanations, because you have a better feeling for what is a likely explanation and what is not. You know that it's more probable that sleight of hand is behind the snake trick or that some natural but little-known phenomenon is the secret.

    Being logical requires the ability to identify strange events, and it requires a knowledge of the best way to go about explaining why the events appear to be happening. A strange event is an improbable one, and probability is always assessed against a base of background knowledge and available evidence. Strange events or statements are improbable because they conflict with what else you believe.

    The core of background knowledge that you use in making judgments of improbability is called common sense. It is the knowledge that most of us acquire in the normal process of growing up in our society, that cars need a steering wheel, that sticks don’t become snakes, and all that. The common sense of today's logical reasoner is quite different from the common sense of the ancient Egyptian.

    Because of your common sense, you probably won't believe an email from Nigeria offering to pay you to help launder some money, and you wouldn’t believe the following headline if it were to appear in a supermarket tabloid:

    DYING MAN'S BRAIN PUT IN COMA WOMAN

    You probably know a few people who could use a good brain transplant. The gullible person will buy the newspaper to learn more details about the world's first successful brain snatch. However, you as a logical reasoner will first ask yourself, "Why am I finding out about this in the supermarket checkout line?" If it is true, why haven't you heard about it on the TV news, or from your friends? This headline is inconsistent with your background knowledge about the state of medicine today. You don't have to be a doctor to know that brain transplants have yet to be attempted. At most, small bits of brain tissue have been transplanted. If a brain transplant were even going to be attempted, there would have been a lot of advance publicity. A person who did not know these facts of medicine could easily be conned by the headline. For the rest of us, the most it should do is sensitize us to noticing whether other newspapers or the TV news mention any recent brain transplant attempts. Reading the article in the tabloid would be unlikely to provide the logical reasoner with any good reason to believe the original headline.

    Acceptance is a matter of degree. Even for claims you accept, you will accept some more strongly than others.

    Can you spot the faulty assumption underlying the following word problem in this fifth-grade mathematics book? Look at it from the perspective of a book editor who is trying to decide whether to publish the book and is checking the quality of the math problems.

    Dr. Richard Feynman and his daughter Melissa visit a glass factory that makes marbles. Marbles are stored in different colored bins, and there are signs about the colors and temperatures of the marbles:

    green bin marbles: 215 degrees
    yellow bin marbles: 150 degrees
    blue bin marbles: 70 degrees.

    Melissa collects one marble from the green bin and three from the yellow bin. Richard collects one marble from the blue bin and two from the green bin. What is the total of the temperatures of the marbles collected by the father and daughter?

    This is a very strange question, isn't it? The ridiculous assumption is that adding these temperatures gives a total worth knowing.

    The critical thinker, unlike the naive thinker, is on guard against accepting stupid assumptions. Yet there are situations in which, even though they are ridiculous, you might still need to accept them, at least temporarily. For example, if you are a student in an arithmetic class, and your teacher seems to be serious about wanting you to answer the question above about adding the temperatures of marbles, then you apply your critical thinking skills and think, "OK, it's a dumb question, but I'll do the math computation and get the right answer."

    We are continually asked to accept assumptions in arguments, definitions, explanations, and interpretations of the world around us. As critical thinkers, we need to be aware of those assumptions and consider whether we really want to make them.

    Exercise \(\PageIndex{1}\)

    Suppose you are having dinner with a married couple from your apartment building. You pass the husband the rice, but he declines and says he doesn’t like to eat rice because this was almost the only thing he had to eat for a month while he was captured and held as a P.O.W. (prisoner of war) in the last war. That’s an understandable reason to avoid rice, but then his wife comments that she doesn’t like to eat rice because she was force fed rice while kidnapped by space aliens. Oops! When you laugh, and she responds that she’s not kidding and that four years ago she was captured and held for three days in an alien spaceship that was hiding in a trench in the middle of the Pacific Ocean, then what should you think? You probably should think that she’s a little crazy or very foolish. Why are you justified in making this evaluation of your neighbor?

    Answer

    First off, her claim about kidnapping by aliens from outer space is an extraordinary claim. Really odd. Common sense says that no one has ever been kidnapped by space aliens. If someone actually were, it would be the biggest news you’ve ever heard in your life, and everyone you’ve ever met would know about it, even if the abduction were to have occurred in some obscure country. The experts all say that creatures from outer space have never visited our planet. There’s no evidence, and all significant claims that it occurred did not check out. They say serious claims of alien abduction are just the product of foolish misunderstanding or an insane mind. So, that’s why it’s perfectly OK to evaluate your neighbor as being a little crazy or very foolish. Yes, you have to be open to the possibility that she has access to information that no one else has, but the burden of proof is on her to produce extraordinarily good evidence that what she’s saying is correct. Her passing a lie detector test wouldn’t count as good evidence, would it?


    This page titled 4.2: When Should You Accept Unusual Statements? is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by Bradley H. Dowden.

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