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Comment by logical on Bayes' Theorem Illustrated (My Way) · 2010-06-04T17:13:11.708Z · LW · GW

"Your analogy doesn't hold, because each spin of the roulette wheel is a separate trial, while choosing a door and then having the option to choose another are causally linked."

No, they are not causally linked. It does not matter what door you choose, you don't influence the outcome in any way at all. Ultimately, you have to choose between two doors. In fact, you don't "choose" a door at first at all. Because there is always at least one goat behind a door you didn't choose, you cannot influence the next action, which is for Monty to open a door with a goat. At that point it's a choice between two doors.

Comment by logical on Bayes' Theorem Illustrated (My Way) · 2010-06-04T16:58:25.597Z · LW · GW

Are you serious? Are you buying this? Ok - let me make this easy: There NEVER WAS a 33% chance. Ever. The 1-in-3 choice is a ruse. No matter what door you choose, Monty has at least one door with a goat behind it, and he opens it. At that point, you are presented with a 1-in-2 choice. The prior choice is completely irrelevant at this point! You have a 50% chance of being right, just as you would expect. Your first choice did absolutely nothing to influence the outcome! This argument reminds me of the time I bet $100 on black at a roulette table because it had come up red for like 20 consecutive times, and of course it came up red again and I lost my $$. A guy at the table said to me "you really think the little ball remembers what it previously did and avoids the red slots??". Don't focus on the first choice, just look at the second - there's two doors and you have to choose one (the one you already picked, or the other one). You got a 50% chance. (by the way - sorry if I posted this twice?? Or in the wrong place?)

Comment by logical on Bayes' Theorem Illustrated (My Way) · 2010-06-04T16:43:08.089Z · LW · GW

Are you serious? Are you buying this? Ok - let me make this easy: There NEVER WAS a 33% chance. Ever. The 1-in-3 choice is a ruse. No matter what door you choose, Monty has at least one door with a goat behind it, and he opens it. At that point, you are presented with a 1-in-2 choice. The prior choice is completely irrelevant at this point! You have a 50% chance of being right, just as you would expect. Your first choice did absolutely nothing to influence the outcome! This argument reminds me of the time I bet $100 on black at a roulette table because it had come up red for like 20 consecutive times, and of course it came up red again and I lost my $$. A guy at the table said to me "you really think the little ball remembers what it previously did and avoids the red slots??". Don't focus on the first choice, just look at the second - there's two doors and you have to choose one (the one you already picked, or the other one). You got a 50% chance.