Excerpt from Chapter IV (The Humanitarian Revolution: Superstitious Killing: Human Sacrifice, Witchcraft, and Blood Libel) from The Better Angels of Our Nature by Steven Pinker

“Witch hunts are always vulnerable to common sense. Objectively speaking, it is impossible for a woman to fly on a broomstick or to turn a man into a cat, and these facts are not too hard to demonstrate if enough people are allowed to compare notes and question popular beliefs. Throughout the Middle Ages there were scattered clerics and politicians who pointed out the obvious, namely that there is no such thing as a witch, and so persecuting someone for witchcraft was a moral abomination. (Unfortunately, some of these skeptics ended up in the torture chambers themselves.) These voices became more prominent during the Age of Reason, and included influential writers such as Erasmus, Montaigne, and Hobbes.

Some officials became infected with the scientific spirit and tested the witchcraft hypothesis for themselves. A Milanese judge killed his mule, accused his servant of committing the misdeed, and had him subjected to torture, whereupon the man confessed to the crime; he even refused to recant on the gallows for fear of being tortured again. (Today this experiment would not be approved by committees for the protection of human subjects in research.) The judge then abolished the use of torture in his court. The writer Daniel Mannix recounts another demonstration:

‘The Duke of Brunswick in Germany was so shocked by the methods used by Inquisitors in his duchy that he asked two famous Jesuit scholars to supervise the hearings. After a careful study the Jesuits told the Duke, “The Inquisitors are doing their duty. They are arresting only people who have been implicated by the confession of other witches.”

“Come with me to the torture chamber,” suggested the Duke. The priests followed him to where a wretched woman was being stretched on the rack. “Let me question her,” suggested the Duke. “Now woman, you are a confessed witch. I suspect these two men of being warlocks. What do you say? Another turn of the rack, executioners.”

“No, no!” screamed the woman. “You are quite right. I have often seen them at the Sabbat. They can turn themselves into goats, wolves, and other animals.”

“What else do you know about them?” demanded the Duke.

“Several witches have had children by them. One woman even had eight children whom these men fathered. The children had heads like toads and legs like spiders.”

The Duke turned to the astonished Jesuits. “Shall I put you to the torture until you confess, my friends?”‘

One of the Jesuits, Father Friedrich Spee, was so impressed that he wrote a book in 1631 that has been credited with ending witchcraft accusations in much of Germany. The persecution of witches began to subside during the 17th century, when several European states abolished it. The year 1716 was the last time a woman was hanged as a witch in England, and 1749 was the last year a woman was burned as a witch anywhere in Europe.

In most of the world, institutionalized superstitious killing, whether in human sacrifice, blood libel, or witch persecution, has succumbed to two pressures. One is intellectual: the realization that some events, even those with profound personal significance, must be attributed to impersonal physical forces and raw chance rather than the designs of other conscious beings. A great principle of moral advancement, on a par with ‘Love thy neighbor’ and ‘All men are created equal,’ is the one on the bumper sticker: ‘Shit happens.’ The other pressure is harder to explain but just as forceful: an increased valuation of human life and happiness.”

The full book can be found here.

Excerpt from Chapter XII (Confirmation Bias) of The Skeptics’ Guide to the Universe by Steven Novella, et al.

“There are four cards on the table before you. They each have a letter on one side and a number on the other. I have a hypothesis – every card that has a vowel on one side has an even number on the other. The four cards are showing A, 7, D, and 4.

The question for you is this: Which cards do I need to flip over in order to test my hypothesis? Go ahead and decide before reading ahead to the answer.

This was a psychological study performed by P.C. Wason in 1966. In his original study only 10 percent of subjects got the right answer (which means they turned over all the cards they needed to and none of the cards they did not need to). Later replications yielded similar results.

The correct answer is that you need to turn over A and 7 but not D or 4. The reason is, these are the two cards that can falsify your hypothesis. If A doesn’t have an even number on the other side, or 7 has a vowel, the hypothesis is wrong. D and 4 are irrelevant, because they cannot test your rule. Most people will turn over 4 to see if there’s a vowel on the other side, but this will still not prove the rule, and the 4 can’t falsify the rule because it’s okay to have an even number opposite a consonant. Instinctively, however, people look for evidence to confirm their hypothesis rather than evidence that can disprove it.

An interesting wrinkle to the Wason selection task is that the results differ depending on context. If, for example, one side of the cards has ages, and the other what someone is drinking, people have no problem figuring out if there is any underage drinking going on. Our instincts are better suited to social interactions than abstract problems, apparently.

But the core lesson remains – if you want to test your hypothesis, try to prove it wrong. Do not only look for evidence to prove it right.”

The full book can be purchased here.

The authors’ website, including podcast, can also be found here.