OK it's time for a curiously counter-intuitive conundrum! It's called the Monty Hall problem when it appears in The Curious Incident of the Dog in the Night-time (a favourite book of mine!), and has also featured in different guises elsewhere. In this version....

You are on a TV Game Show. You have the chance to win a car....or a goat. There are three doors in front of you. You are told that behind two of the doors there is a goat, and behind the other there is a car. If you open the correct door you get to keep the car (you would prefer the car!).

But first, the Gameshow host invites you to choose one of the three doors, tell him which one it is, but not to open it. He then opens one of the other two doors, to reveal a goat (he can see what is inside each door and will always open one with a goat in). You can then choose to open one of the two closed doors. The question is, should you stick to your original choice, or change to the other door?

Qu'en pensez vous?