Mind Hacks

Hack #72. Detect Cheaters

Our sense of logic is much better when applied to social situations than used in abstract scenarios.

Despite the old saying that we’re ruled by our emotions, it’s tempting to believe that we have at least some intuitive sense of logic. The various forms of logic such as syllogisms and deductive and inductive reasoning ¹ seem so simple and fundamental that you might expect that the rules are hardwired into our brains. After all, since we’re constantly told that our neurons are the equivalent of computer processors, shouldn’t our brains be able to handle a little bit of logic?

See how you do on these logical puzzles.

In Action

Each of the cards in Figure 7-1 has a letter on one side and a number on the reverse. If I told you there was a rule stating that a card with a vowel on one side must have an even number on the reverse, which of these cards would you need to turn over to prove or disprove this rule?

Note

Give it a whirl before reading on.

Many people turn over A and 2—but that’s not quite right. While turning over A will tell you whether “one side” of the rule is true (if vowel, then even number), turning over 2 won’t tell you any more. It doesn’t matter whether 2 has a K or an A on its reverse—the rules doesn’t specify either being true. Along with A, the other card you need to turn over is 7. If 7 has an A on its reverse, then the rule is disproved no matter what the A has on its reverse. You need to turn over A and 7.

Figure 7-1. Each card has a letter ...