Why smart people do dumb things

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A Nobel Prize in Chemistry. Over 1,200 research papers and books. Ranked the 16th most important scientist of all time.

And yet for decades, against all available evidence, Linus Pauling wholeheartedly pursued and promoted megavitamin therapy. In particular, he was convinced that taking large doses of vitamin C could cure ailments ranging from the common cold to cancer.

As research mounted against such therapies and the rest of the scientific community lost interest, Pauling would spend his later years touting them. He founded an institute, published papers, and wrote books that promoted vitamin C as a cure-all.

How could such a scientific genius believe so strongly in something with so little scientific evidence?

To understand how this could happen, we have to take a closer look at what it means to be smart.

You�ve heard of IQ, or intelligence quotient. IQ measures cognitive speed and certain abstract aptitudes such as verbal, mathematical, and spatial abilities. Einstein had a high IQ.

But IQ doesn�t take into account what happens in real-world situations, where people have to make complex judgments based on limited or messy information, where conflicting motives and beliefs might be at play.

In the real-world, judgments are often swayed by cognitive biases, or systematic departures from logical decision-making and rationality. Thinking rationally means choosing the best option given your goals, and holding beliefs that are in line with the evidence[2].

IQ doesn�t measure this kind of rational thought. It doesn�t, in other words, measure sound judgment in everyday life. It�s one kind of smart, but it�s not everything.

Let�s return to Pauling. He was diagnosed with Bright�s disease, a kidney ailment, at age 40. When it was recommended that he switch to a low-protein, low-salt diet, and take vitamin supplements, he did so[3,4]. And, to his amazement, this regimen worked! From this point on, he viewed vitamins as critical to a healthy life.

A couple decades later, Pauling was introduced to vitamin C megadosing as a way to prevent the common cold. He began taking 3 grams daily, and noticed that he tended to stay healthy. In 1970, he published Vitamin C and the Common Cold, which recommended that everyone take at least 1 gram per day. A revised version recommended higher doses, and claimed flu prevention as an additional benefit. Later books would recommend even higher doses, to prevent heart disease and cancer.

When Pauling, a preeminent scientist, spoke, the scientific community listened. And then they tested his claims in randomized, double-blind, placebo-controlled experiments with adequate sample sizes.

Study after study found the same thing: vitamin C did not prevent or cure cancer, heart disease, the flu, or even the common cold[6-10]. And, each time, Pauling reacted the same way: he pointed out flaws he saw in the experiments, and accused his critics of being biased. When a researcher at his own institute found that high doses of vitamin C increased the incidence of skin cancer in lab mice, he fired the researcher, called him �amateurish,� and destroyed the evidence[11].

For the rest of his life, Pauling remained convinced of the power of vitamin C therapy, taking at least 12 grams daily, until he died at age 93 of prostate cancer[11].

Pauling was undeniably intelligent�he revolutionized our understanding of how atoms bond together in chemicals�but he was prone to common cognitive biases that hijack rational thought:

  • Primacy and availability. His first experience with vitamins was personal and emotionally vivid�he took them at a time when he was suffering from a serious illness, and soon after got better�and this experience would always be given outsize weight in his mind.
  • Illusory correlation. He became convinced that vitamin C prevents colds after trying it himself. But, he was aware of the hypothesis, and there was no control group, so it�s impossible to say why he didn�t get sick as much. Earlier, he�d concluded that taking vitamins improved his Bright�s disease�but it�s likely the low-protein, low-salt diet was what kept his condition under control[4].
  • Confirmation bias. He found evidence for his preexisting beliefs in small studies and personal experience, and was quick to dismiss all of the evidence against his beliefs as flawed.
  • Escalation of commitment. At any point, he could have said, �I was wrong� and walked away from his advocacy of vitamin therapies. But, having invested years of his life in the cause, he instead dug in and became an even more ardent supporter.

Clearly, IQ isn�t everything. To study people�s decision-making in real life, psychologist Keith Stanovich and colleagues created a new measure, the rationality quotient, or RQ[1].

RQ fills in some of the gaps left by IQ, measuring people�s ability to recognize and correct their own cognitive biases and make more rational judgments. Interestingly, those with a high IQ are no more or less likely to have a high RQ. Geniuses such as Pauling aren�t any more likely to behave rationally than the average person[1]!

You can think of it this way: IQ measures abstract intelligence, while RQ measures practical intelligence.

And the good news is, compared to IQ, RQ is more easily improved with training. Learning about cognitive biases, noticing them in everyday life, and correcting for them can increase your ability to make better, more rational decisions[1].


1. Hambrick, D. (2017) The Difference Between Rationality and Intelligence. The New York Times.

2. Stanovich, K.E., & West, R.F. (2014). The assessment of rational thinking: IQ =? RQ. Teaching of Psychology, 41, 265-271.

3. Peitzman, S.J. (2007). Dropsy, dialysis, transplant: a short history of failing kidneys. Baltimore: Johns Hopkins University Press. pp. 72�8; 190.

4. Glomerulonephritis. In MedlinePlus.gov.

5. Dunitz, J. D. (1996). Linus Carl Pauling. 28 February 1901�19 August 1994. Biographical Memoirs of Fellows of the Royal Society, 42, 316�326.

6. Vitamin C Fact Sheet for Health Professionals. National Institute of Health.

7. Robinson, J. Vitamin C for the Common Cold. WebMD.

8. Creagan, E.T., Moertel, C.G., O’Fallon, J.R. (1979). Failure of high-dose vitamin C (ascorbic acid) therapy to benefit patients with advanced cancer. A controlled trial. The New England Journal of Medicine, 301, 687�90.

9. Moertel, C.G., Fleming, T.R., Creagan, E.T., Rubin, J., O’Connell, M.J., Ames, M.M. (1985). High-dose vitamin C versus placebo in the treatment of patients with advanced cancer who have had no prior chemotherapy: a randomized double-blind comparison. The New England Journal of Medicine, 312, 137�41.

10. Tschetter, L., et al. (1983). A community-based study of vitamin C (ascorbic acid) in patients with advanced cancer. Proceedings of the American Society of Clinical Oncology, 2, 92.

11. Barrett, S. The dark side of Linus Pauling’s legacy. quackwatch.com.