If you phrase it adversarially it makes more sense... 2/3 of the time you select a goat and force Monty to reveal the other goat. For those 2/3, you're guarante

If you phrase it adversarially it makes more sense... 2/3 of the time you select a goat and force Monty to reveal the other goat. For those 2/3, you're guaranteed to get a car by switching. The remaining third you get a goat. If you take the "stay" strategy... 1/3 you hit the car and keep it. 2/3 you hit a goat and keep it. In summary... "switch" is 2/3 car, "stay" is 2/3 goat. In these times you should choose "stay" and hope to get a goat so you can turn grass into food. Cars are overrated.