# mistakes in analogous puzzles from The Tipping Point

In the book 'The Tipping Point', Malcolm Gladwell cites two puzzles and draws an analogy between them, in fact he claims the two are equivalent. I believe there are some problems with both puzzles, and the analogy as well. Do you see the same problems, and are there any suggestions to fix this?

The first riddle:

Consider the following brain teaser. Suppose I give you four cards, labeled with the letter A and D and the numerals 3 and 6. The rule of the game is that a card with a vowel on it always has an even number on the other side. Which of the cards would you have to turn over to prove this rule to be true? The answer is two: the A card and the three card. The overwhelming majority of the people given this test, though, don't get it right. They tend to answer just the A card, or the A and the 6. It's a hard question.

Here, the D-card should be turned over as well, as there is no indication that cards cannot have letters on both sides.

And now the second:

But now let me pose another question. Suppose four people are drinking in a bar. One is drinking Coke. One is sixteen. One is drinking beer and one is twenty-five. Given the rule that no one under twenty-one is allowed to drink beer, which of those people's IDs do we have to check to make sure the law is being observed? Now the answer is easy, in fact, I'm sure that almost everyone will get it right: The beer-drinker and the sixteen-year-old. But, as the psychologist Leda Cosmides (who dreamt up this example) points out, it is exactly the same puzzle as the A, D, 3 and 6 puzzle. The difference is that it is framed in a way that makes it about people, instead of about numbers, and as human beings we are a lot more sophisticated about each other than we are about the abstract world.

But checking the ID of the sixteen-year-old doesn't make sense, you already know his age. He can still be drinking tequila while you read his birth-date.

The analogy is incorrect after these mistakes. If those two mistakes are fixed, by adding the rule 'Cards always have a letter on one side and a number on the other' to the first puzzle, and in the second case alter the wording so that we may also check the drink of the sixteen-year-old, the analogy is correct, right?