To a decision-theoretic agent, the value of information is always nonnegative
This seems false. If I selectively give you information in an adversarial manner, and you don’t know that I’m picking the information to harm you, I think it’s very clear that the value of the information you gain can be strongly negative.
This seems false. If I selectively give you information in an adversarial manner, and you don’t know that I’m picking the information to harm you, I think it’s very clear that the value of the information you gain can be strongly negative.