Note that Kelly is valid under the assumption that you know the true probabilities. II do not know whether it is still valid when all you know is a noisy estimate of true probabilities - is it? It definitely gets more complicated when you are betting against somebody with a similarly noisy estimate of the same probably, as at some level you now need to take their willingness to bet into account when estimating the true probability - and the higher they are willing to go, the stronger the evidence that your estimate may be off. At the very least, that means that the uncertainty of your estimate also becomes the factor (the less certain you are, the more attention you should pay to the fact that somebody is willing to bet against you). Then the fact that sometimes you need to spend money on things, rather than just investing/betting/etc, and that you may have other sources of income, also complicates the calculus.
The way you described the chess/marriage/etc market, it's a bit vulnerable. Imagine there is a move that appears to be a very strong one, but with a small possibility of a devastating countermove that is costly for market participants to analyze. There is an incentive to bet on it - if the countermove exists, hopefully somebody will discover it, heavily bet against the move, and cause the price to drop enough that it is not taken, and the bets are refunded. If no countermove exists, the bet is a good one, and is profitable. But if nobody bothers to check for the countermove, and it exists, everybody (those who bet on the move, and the decision makers who made the move) are in trouble, but it could still be the case that no bettors have enough incentive to check for countermove (if it exists, they do not derive any benefit from the significant mispricing of the move, as you just refund the bets).
Right, which is why the claim is immediately more suspect if Xavier is a close friend/relative/etc.
I do not see the connection. The gist of Newcomb's Problem does not change if the player is given a time limit (you have to choose within an hour, or you do not get anything). Time-limited halting problem is of course trivially decidable.
I think your analysis of "you're only X because of Y" is missing the "you are doing it wrong" implicit accusation in the statement. Basically, the implied meaning, I think, is that while there are acceptable reasons to X, you are lacking any of them, but instead your reason for X is Y, which is not one of the acceptable reasons. Which is why your Z is a defense - claiming to have reasons in the acceptable set. And another defense might be to respond entirely to the implied accusation and explain why Y should be an OK reason to X. "You're only enjoying that movie scene because you know what happened before it" - "Yeah, and what's wrong with that?"
Random data point - https://ftx.com/trade/TRUMPFEB ("Trump is the President on Feb 1st, 2021") is currently at 0.142 (14.2% probability it will happen)...
In mathematics, axioms are not just chosen based of what feels correct - instead, the implications of those axioms are explored, and only if those seem to match the intuition too, then the axioms have some chance of getting accepted. If a reasonably-seeming set axioms allows you to prove something that clearly should not be provable (such as - in the extreme case - a contradiction), then you know your axioms are no good.
Axiomatically stating a particular ethical framework, then exploring the consequences of the axioms in the extreme and tricky cases can serve a similar purpose - if simingly sensible ethical "axioms" lead to completely unreasonable conclusions, then you know you have to revise the stated ethical framework in some way.
Perhaps also higher availability of testing and higher awareness means more people with mild symptoms get tested?
Well, this is Committee on Armed Services - obviously the adversarial view of things is kind of a part of their job description... (Not that this isn't a problem, just pointing out that they are probably not the best place to look for a non-adversarial opinion).
More of an anecdote than research, but I recently became aware of Dr. A.J Cronin’s novel “The Citadel” published in 1937 and the claim that the book prompted new ideas about medicine and ethics, inspiring to some extent the UK NHS and the ideas behind it. Did not look into this much myself, but certainly a very fascinating story, if true.