Ah, I forgot that “the case of the baseball card” is actually two cases. I think you’re right about the case where Beth gets given a new card; if there are lots of Beths, there’s a large net utility gain. But I don’t think that works in the case where Adam’s card gets given to one of the Beths; the loss to him is still close to the market value of the card.
It seems plausibly true if we think only of the cases where… something like “A loses power because B gets something they want, but A’s circumstances ignoring B are unchanged”. But I don’t immediately trust that to be a sensible set of cases to think about, in more complicated scenarios.
Ah, I forgot that “the case of the baseball card” is actually two cases. I think you’re right about the case where Beth gets given a new card; if there are lots of Beths, there’s a large net utility gain. But I don’t think that works in the case where Adam’s card gets given to one of the Beths; the loss to him is still close to the market value of the card.
It seems plausibly true if we think only of the cases where… something like “A loses power because B gets something they want, but A’s circumstances ignoring B are unchanged”. But I don’t immediately trust that to be a sensible set of cases to think about, in more complicated scenarios.