Timeline for Two envelope (sub)-problem / related problem
Current License: CC BY-SA 3.0
14 events
| when toggle format | what | by | license | comment | |
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| Feb 28, 2016 at 19:56 | history | made wiki | Post Made Community Wiki by whuber♦ | ||
| Jan 30, 2016 at 21:26 | comment | added | John | (re-posting as I should have put it here): In the scenario I posed at the top, the player is told that money was put in one envelope, let's call it envelope A. Then a coin was flipped to determine double or half in envelope B. If the player is told which envelope is which, it seems obvious he should choose envelope B. But then what is the player to think when he opens B and sees a particular amount of money, say £100? That it was more likely the starting amount, placed in A, was £50 as opposed to £200? If not, shouldn't he want to swap, thus contradicting his original reasoning in choosing B? | |
| Jan 30, 2016 at 10:27 | comment | added | delusionist | See Addendum 3. I think this is it! Maybe I should have waited until I got it all figured out, but I think the run up was informative. (I hope so) Let me know if this solves the paradox for you. | |
| Jan 30, 2016 at 6:20 | comment | added | delusionist | See Addendum 2. | |
| Jan 30, 2016 at 4:40 | comment | added | delusionist | OK, I think I got it. See my "Addendum 1" edit below. | |
| Jan 29, 2016 at 23:53 | comment | added | delusionist | OK, I can see that my logic in the "Hmmmm" post is faulty. I tried to delete it, but either way, I think what it says in wrong. Right now it is still there but surrounded by a reddish color. Can you read it? Just curious. If I come up with something more intelligent, I'll let you know. | |
| Jan 29, 2016 at 18:31 | comment | added | delusionist | See my answer below starting with "Hmmmm,..." | |
| Jan 28, 2016 at 12:23 | comment | added | John | What do you say to the person who has opened an envelope and is looking at, say, £100? They say they agree with your point as far as it goes, but they say that it is 50 : 50 whether £100 is the smaller or the larger amount, so the options are £50 and £200 for the other envelope, with an equal chance, and therefore they are inclined to swap. | |
| Jan 27, 2016 at 11:42 | comment | added | delusionist | Read below first. So, every time you think "I can either double or halve my money by trading," think next "Not exactly. I can only double my money if I have the smaller amount, and I can only halve my money if I have the larger amount."Doing this removes the paradox. | |
| Jan 25, 2016 at 15:53 | comment | added | John | ... However, putting it that way can of course be seen to simply re-state the paradox. It is indeed all about doubling the smaller amount or halving the larger amount. But, if I am looking at, say, £100, I am then left wondering whether £100 is the smaller or the larger amount, and the paradox returns (apparently). One line of argument in response to this is to play around with calculations of the prior probability of finding a given amount in an envelope. Personally I find that very unconvincing, which is what I was getting at in the scenario above. | |
| Jan 25, 2016 at 15:47 | comment | added | John | I don't disagree with any of that. | |
| Jan 24, 2016 at 14:59 | review | Late answers | |||
| Jan 24, 2016 at 15:02 | |||||
| Jan 24, 2016 at 14:44 | review | First posts | |||
| Jan 24, 2016 at 14:49 | |||||
| Jan 24, 2016 at 14:42 | history | answered | delusionist | CC BY-SA 3.0 |