Fifteen Eighty Four

Academic perspectives from Cambridge University Press


Test Your Good Thinking

Good ThinkingWhat do economists mean when they refer to you as a “rational agent”? Why might a psychologist label your idea a “creative insight”? And how can different scientists disagree on the results of experiments that assess our risk for disease? The problem-solving methods that these experts use affect our daily lives, determining whether we are guilty or innocent, where we should invest our money, and whether the medicine we are taking is effective. But their decisions often seem counterintuitive to you and me – and sometimes they just seem wrong.

How does our thinking differ from the experts? Test yourself by answering these questions from Denise Cummins’ new book, GOOD THINKING: Seven Powerful Ideas That Influence the Way We Think. You’ll see how most people tackle the challenges posed here – and then learn what the experts would do.

Want more? Find an interview with Denise Cummins and a readers guide on the Cambridge Book Club page. Plus, get 30% off your copy this month only, when you use the code LIGHTBULB.

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Question: A trolley is running out of control down a track toward five people. You are on a bridge above its path. There is a fat man next to you; if you push the fat man on the track, the five will survive, but the fat man will die. Should you proceed?

What most people think: In this situation, 80% of people typically say that pushing the man is wrong.

What the experts think: English philosopher Jeremy Bentham says you should. He proposed the idea of utilitarianism, whose core principle states that moral actions cause “the greatest good for the greatest number of people.” To be a moral agent means to always act in such a way as to promote pleasure and avoid pain for those whose interests are affected by your actions. He would push the man.


Question: You have been given $2,000. You now have to choose either to play it safe, and lose $500, or take a risk and flip a coin. If it’s heads, you lose $1,000. If it’s tails, you lose nothing. What should you do?

What most people think: Most people choose to take the risk, because they want to avoid losing the $500. When faced with possible loses, we tend to choose risky alternatives.

What the experts think: Now think about it this way: You have been given $1,000. You have to choose to play it safe, and get $500 more, or take a risk and flip a coin. If it’s heads, you gain $1,000 more. If it’s tails, you gain nothing. Most people will play it safe. But if you work with probabilities, you know that it is exactly the same bet. Each has a 50-50 chance of $1,000 versus $2,000 or simply taking the money. It doesn’t matter which you choose.


Question: Imagine that you are the first person to hypothesize that low serotonin levels lead to depression. You are give the opportunity to examine four patients. The first patient has low serotonin levels, the second has normal serotonin levels, the third has been diagnosed with depression, and the fourth is not depressed. You don’t have much time, so you must choose which patient or patientsto examine. Which do you choose?

What most people think: Most people in this study by psychologist Peter Watson chose to examine the patient with low serotonin levels to see if the patient was depressed, and then examine the depressed patient to see if serotonin levels were low. But this would only select those cases that could confirm your hypothesis.

What the experts think: A logician might argue that your hypothesis can take the form “If P, then Q.” The statement is false only when P is true but Q is false. So, the best hypothesis-testing strategy would be to examine the patient with low serotonin levels and the patient who is not depressed. Finding a patient with low serotonin levels (P) and no depression (false Q) would provide proof that the hypothesis is false.

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