You’re proving too much with your anti-mugger argument. This argument essentially invalidates EV reasoning in all practical cases.
For example, you could use EV reasoning to determine that you should give to an animal charity. But then you could imagine a demon whose sole purpose is to torture everyone on earth for the rest of time if you give to that animal charity. The probability of the demon is very small, but as you say you can make the negative payoff associated with the demon arbitrarily large, so that it becomes a very bad idea to give to the animal charity on EV grounds.
Being able to construct examples such as these means you can never justify doing anything through EV reasoning. So either your argument is wrong, or we give up on EV reasoning altogether.
You’re proving too much with your anti-mugger argument. This argument essentially invalidates EV reasoning in all practical cases.
For example, you could use EV reasoning to determine that you should give to an animal charity. But then you could imagine a demon whose sole purpose is to torture everyone on earth for the rest of time if you give to that animal charity. The probability of the demon is very small, but as you say you can make the negative payoff associated with the demon arbitrarily large, so that it becomes a very bad idea to give to the animal charity on EV grounds.
Being able to construct examples such as these means you can never justify doing anything through EV reasoning. So either your argument is wrong, or we give up on EV reasoning altogether.