Bob’s prior in the first sense is not factual knowledge, it’s a description of which worlds Bob considers how important, so Alice can’t improve on it by knowing something that Bob doesn’t. A difference in priors in the first sense reflects different distributions of moral relevance associated with possibilities. When Alice knows something that Bob doesn’t, it is a statement about her priors in the second sense, not the first sense.
Thus, to the extent that Alice doesn’t assume Bob’s priors in the first sense, Alice doesn’t follow Bob’s preference, which would be a failure of perfect altruism. Alice’s prior doesn’t reflect different (or additional) knowledge, so its use would not be an improvement in the sense of Bob’s preference.
Bob’s prior in the first sense is not factual knowledge, it’s a description of which worlds Bob considers how important, so Alice can’t improve on it by knowing something that Bob doesn’t. A difference in priors in the first sense reflects different distributions of moral relevance associated with possibilities. When Alice knows something that Bob doesn’t, it is a statement about her priors in the second sense, not the first sense.
Thus, to the extent that Alice doesn’t assume Bob’s priors in the first sense, Alice doesn’t follow Bob’s preference, which would be a failure of perfect altruism. Alice’s prior doesn’t reflect different (or additional) knowledge, so its use would not be an improvement in the sense of Bob’s preference.