Because it isn't different really. It is always a goat door that is opened, so you don't gain any information about your door by the opening of the goat door.

Because it isn't different really. It is always a goat door that is opened, so you don't gain any information about your door by the opening of the goat door. I'm thinking of a number between 1 and 10, guess it. If I now tell you a number I promise is not the one I was thinking and not your number, you have no more information about if you were correct.