In general though, this consideration is likely to be irrelevant. Most universes will be nowhere near the upper or lower bounds, and the chance of any individual’s decision being single-handedly responsible for doing a universe scale shifts toward a utility bound is so tiny that even estimating orders of magnitude of the unlikelihood is difficult. These are angels-on-head-of-pin quibbles.
That makes sense. So it sounds like the Egyptology Objection is almost a form of Pascal’s Mugging in and of itself. If you are confronted by a Mugger (or some other, slightly less stupid scenario where there is a tiny probability of vast utility or disutility) the odds that you are at a “place” on the utility function that would affect the credibility threshold for the Mugger one way or another are just as astronomical as the odds that the Mugger is giving you. So an agent with a bounded utility function is never obligated to research how much utility the rest of the universe has before rejecting the mugger’s offer. They can just dismiss it as not credible and move on.
And Mugging-type scenarios are the only scenarios where this Egyptology stuff would really come up, because in normal situations with normal probabilities of normal amounts of (dis)utility, the rescaling and reshifting effect makes your “proximity to the bound” irrelevant to your behavior. That makes sense!
I also wanted to ask about something you said in an earlier comment:
I suspect most of the “scary situations” in these sorts of theories are artefacts of trying to formulate simplified situations to test specific principles, but accidentally throw out all the things that make utility functions a reasonable approximation to preference ordering. The quoted example definitely fits that description.
I am not sure I understand exactly what you mean by that. How do simplified hypotheticals for testing specific principles make utility functions fail to approximate preference ordering? I have a lot of difficulty with this, where I worry that if I do not have the perfect answer to various simplified hypotheticals it means that I do not understand anything about anything. But I also understand that simplified hypotheticals often causes errors like removing important details and reifying concepts.
The main argument I’ve heard for this kind of simplification is that your altruistic, morality-type preferences ought to be about the state of the external world because their subject is the wellbeing of other people, and the external world is where other people live. The linearity part is sort of an extension of the principle of treating people equally. I might be steelmanning it a little, a lot of times the argument is less that and more that having preferences that are in any way weird or complex is “arbitrary.” I think this is based on the mistaken notion that “arbitrary” is a synonym for “picky” or “complicated.”
I find this argument unpersuasive because altruism is also about respecting the preferences of others, and the preferences of others are, as you point out, extremely complicated and about all sorts of things other than the current state of the external world. I am also not sure that having nonlinear altruistic preferences is the same thing as not valuing people equally. And I think that our preferences about the welfare of others are often some of the most path-dependent preferences that we have.
EDIT: I have sense found this post, which discusses some similar arguments and refutes them more coherently than I do.
Second EDIT: I still find myself haunted by the “scary situation” I linked to and find myself wishing there was a way to tweak a utility function a little to avoid it, or at least get a better “exchange rate” than “double tiny good thing and more-than doubling horrible thing while keeping probability the same.” I suppose there must be a way since the article I linked to said it would not work on all bounded utility functions.