Thinking fast, slow and exhausted
Daniel Kahneman was on Radio 4 today. The author of Thinking Fast and Slow set listeners a couple of logic problems. I put down the broccoli chopping and paid attention. A bat and ball together cost £1.10. The bat costs £1.00 more than the ball. How much does the ball cost? I fell straight into the trap — the ball must cost 10p. I jotted it down, and waited for the next. All roses are flowers. Some flowers fade quickly. Therefore some roses fade quickly. Is the logic right or wrong? WRONG! Just because some flowers fade quickly, it doesn't mean that roses are in that group automatically. And while some roses might fade quickly, it's not because of the reason that 'some flowers fade quickly'. The latter I felt able to 'do': it was a syllogism , and its third part didn't follow from its first two, a logical fallacy. The maths question niggled at me, I felt dumb, because I knew it must be a trap, but I literally couldn't think how to solve i...