So I was browsing the Wikipedia article concerning The Monty Hall Paradox, and I seem to take great issue with the assumption that switching results in a 2/3 probability of winning a car. (hold on pressed enter by mistake... editing now watch this space) My reasons are as follows (and I don't believe this has anything to do with intuition bias) Conditions and assumptions: * This puzzle uses the word "say" before No.1 and No3... Therefore, it could be equally valid that contestant choose 2, or 3 initially * Monty Hall must always choose a goat door. If guessed correctly, this would either be 2 of the goat doors (irrespective of number) decided by an a-priori coin toss before the show and not chosen out of the whim of the presenter. Alternatively, the presenter knows what door has the goat and always opens the door with the goat. Therefore the switch door and the door Monty opens can be in variable order. * Ive never watched this show, so I'm going to ignore all subjective behavioural characteristics (e.g. no right/left door bias) * the presenter must always choose a door with a goat, and always offer a choice to switch or not. * The contestant has no idea what's behind the door. The original puzzle: Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. He then says to you, "Do you want to pick door No. 2?" Is it to your advantage to switch your choice? It is claimed that switching results in a probability of 2/3rds, but it has to be 1/2, factoring all those conditions outlined above. I didn't study Maths or Physics, but this makes perfect logical sense to me.