I don’t think that what you need has any bearing on what reality has actually given you.
As far as I can tell, I would pay Parfit’s Hitchhiker because of intuitions that were rewarded by natural selection. It would be nice to have a formalization that agrees with those intuitions.
or by sneaking in different metaphysics
This seems wrong to me, if you’re explicitly declaring different metaphysics (if you mean the thing by metaphysics that I think you mean). If I view myself as a function that generates an output based on inputs, and my decision-making procedure being the search for the best such function (for maximizing utility), then this could be considered as different metaphysics from trying to cause the most increase in utility for myself by making decisions, but it’s not obvious that the latter leads to better decisions.
As far as I can tell, I would pay Parfit’s Hitchhiker because of intuitions that were rewarded by natural selection. It would be nice to have a formalization that agrees with those intuitions.
This seems wrong to me, if you’re explicitly declaring different metaphysics (if you mean the thing by metaphysics that I think you mean). If I view myself as a function that generates an output based on inputs, and my decision-making procedure being the search for the best such function (for maximizing utility), then this could be considered as different metaphysics from trying to cause the most increase in utility for myself by making decisions, but it’s not obvious that the latter leads to better decisions.