To forestall an objection: I think investing with a goal of improving the world as opposed to maximizing income, is basically the same as giving, so that comes into the category of how to spend, not how much money to allocate for it. If you were investing rather than giving, and had income from it, you'd simply allocate it back into the category.
I apologize for being unclear in my description. At the moment, after all my bills I have money left over. This implicitly goes toward retirement. So it wouldn't be slighting my family to give some more to charity. I also have enough saved to semi-retire today (e.g. if I chose to move to a cheap area I could live like a lower-middle class person on my savings alone), and my regular 401K contributions (assuming I don't retire) would mean that I'll have plenty of income if I retire at 65 or so.
I see what you mean now, I think. I don't have a good model of dealing with a situation where someone can influence the actual updating process either. I was always thinking of a setup where the sorcerer affects something other than this.
By the way, I remember reading a book which had a game-theoretical analysis of games where one side had god-like powers (omniscience, etc), but I don't remember what it was called. Does anyone reading this by any chance know which book I mean?
Maybe I am amoral, but I don't value myself the same as a random person even in a theoretical sense. What I do is I recognize that in some sense I am no more valuable to humanity than any other person. But I am way more valuable to me - if I die, that brings utility to 0, and while it can be negative in some circumstances (aka Life is not worth living), some random person's death clearly cannot do so, people are constantly dying in huge numbers all the time, and the cost of each death is non-zero to me, but must be relatively small, else I would easily be in the negative territory, and I am not.