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> suppose you are asked to assign a probability to the proposition that there was once life on Mars As soon as you accept this question as meaningful, you have
by thomasahle 5y ago
> suppose you are asked to assign a probability to the proposition that there was once life on Mars
As soon as you accept this question as meaningful, you have already come out as a Bayesian. Deutsch would simply say (if I understand him right) that this question is not a matter of probabilities, whereas the coin question is.
- ElevenLathe 5y agoSuppose you were a bookie and somebody wanted to make a million dollar bet on it. You'd love to take the money, but obviously you need a line. How do you pick it?
- MostlyStable 5y agoA bookie would not care at all what the real likelihood of life on mars would be. A bookie would care about the likelihood that would attract approximately equal bets on both sides of the line, since that way they guarantee that they make money. So they would do whatever sociological research would be required to estimate that and set the line accordingly and probably not do an ounce of research on Mars itself.
- ElevenLathe 5y agoThis assumes that there is a chance to create a matched book. This is usually possible for something "liquid" like a big league sporting event, but not always for poorly-followed sports or weird prop bets on low-interest games. Even for liquid games, the book is not always perfectly matched and they may end up with some actual exposure to the outcome of the event. In any case, in this scenario its just one guy looking to make a bet. There is definitely SOME line, possibly million-to-one or higher, that a smart book (or any rational actor) should be willing to take the bet.