Enlightenment Now: The Case for Reason, Science, Humanism, and Progress

The data implied that the skin cream did more harm than good: the people who used it improved at a ratio of around three to one, while those not using it improved at a ratio of around five to one. (With half the respondents, the rows were flipped, implying that the skin cream did work.) The more innumerate respondents were seduced by the larger absolute number of treated people who got better (223 versus 107) and picked the wrong answer. The highly numerate respondents zoomed in on the difference between the two ratios (3:1 versus 5:1) and picked the right one. The numerate respondents, of course, were not biased for or against skin cream: whichever way the data went, they spotted the difference. And contrary to liberal Democrats’ and conservative Republicans’ worst suspicions about each other’s intelligence, neither faction did substantially better than the other.

But all this changed in a version of the experiment in which the treatment was switched from boring skin cream to incendiary gun control (a law banning citizens from carrying concealed handguns in public), and the outcome was switched from rashes to crime rates. Now the highly numerate respondents diverged from each other according to their politics. When the data suggested that the gun-control measure lowered crime, all the liberal numerates spotted it, and most of the conservative numerates missed it—they did a bit better than the conservative innumerates, but were still wrong more often than they were right. When the data showed that gun control increased crime, this time most of the conservative numerates spotted it, but the liberal numerates missed it; in fact, they did no better than the liberal innumerates. So we can’t blame human irrationality on our lizard brains: it was the sophisticated respondents who were most blinded by their politics. As two other magazines summarized the results: “Science Confirms: Politics Wrecks Your Ability to Do Math” and “How Politics Makes Us Stupid.”²⁹

Researchers themselves are not immune. They often trip over their own biases when they try to show that their political adversaries are biased, a fallacy that can be called the bias bias (as in Matthew 7:3, “And why beholdest thou the mote that is in thy brother’s eye, but considerest not the beam that is in thine own eye?”).³⁰ A recent study by three social scientists (members of a predominantly liberal profession) purporting to show that conservatives were more hostile and aggressive had to be retracted when the authors discovered that they had misread the labels: it was actually liberals who were more hostile and aggressive.³¹ Many studies that try to show that conservatives are temperamentally more prejudiced and rigid than liberals turn out to have cherry-picked the test items.³² Conservatives are indeed more prejudiced against African Americans, but liberals turn out to be more prejudiced against religious Christians. Conservatives are indeed more biased toward allowing Christian prayers in schools, but liberals are more biased toward allowing Muslim prayers in schools.

It would also be an error to think that bias about bias is confined to the left: that would be a bias bias bias. In 2010 the libertarian economists Daniel Klein and Zeljka Buturovic published a study aiming to show that left-liberals were economically illiterate, based on erroneous answers to Econ 101 items like these:³³

Restrictions on housing development make housing less affordable. [True]

Mandatory licensing of professional services increases the prices of those services. [True]

A company with the largest market share is a monopoly. [False]

Rent control leads to housing shortages. [True]

(Another item was “Overall, the standard of living is higher today than it was 30 years ago,” which is true. Consistent with my claim in chapter 4 that progressives hate progress, 61 percent of the progressives and 52 percent of the liberals disagreed.) Conservatives and libertarians gloated, and the Wall Street Journal reported the study under the headline “Are You Smarter Than a Fifth Grader?” with the implication that left-wingers are not. But critics pointed out that the items on the quiz implicitly challenged left-wing causes. So the pair ran a follow-up with equally elementary Econ 101 items designed this time to get under the skin of conservatives:³⁴

When two people complete a voluntary transaction, they both necessarily come away better off. [False]

Making abortion illegal would increase the number of black-market abortions. [True]

Legalizing drugs would give more wealth and power to street gangs and organized crime. [False]

Now it was the conservatives who earned the dunce caps. Klein, to his credit, retracted his swipe at the left in an article entitled “I Was Wrong, and So Are You.” As he noted,