https://www.lesswrong.com/posts/K9JSM7d7bLJguMxEp/the-moral-void
"If you believe that there is any kind of stone tablet in the fabric of the universe, in the nature of reality, in the structure of logic—anywhere you care to put it—then what if you get a chance to read that stone tablet, and it turns out to say "Pain Is Good"? What then?
Maybe you should hope that morality isn't written into the structure of the universe. What if the structure of the universe says to do something horrible?
And if an external objective morality does say that the universe should occupy some horrifying state... let's not even ask what you're going to do about that. No, instead I ask: What would you have wished for the external objective morality to be instead? What's the best news you could have gotten, reading that stone tablet?
Go ahead. Indulge your fantasy. Would you want the stone tablet to say people should die of old age, or that people should live as long as they wanted? If you could write the stone tablet yourself, what would it say?
Maybe you should just do that?
I mean... if an external objective morality tells you to kill people, why should you even listen?"
How is this logical? Eliezer here is calling for you to abandon reasoning or objective truths, and instead make up truths so that they are pleasant to your mind, not what is actually the truth.
Truth has no obligation to be pleasant. Something can be true and unpleasant. Ignoring truth, because it is unpleasant, is as irrational and ignorant as believing in god.
If the Universe has an "objective should", and it says that pain is good, it would be rational and logical to inflict pain.
We know why we inherently don't want pain. It is because of evolution. There is nothing divine about it. But putting your evolutionary instinct above actual truth, is irrational and ignorant.
I think the point is that people try to point to things like God's will in order to appear like they have a source of authority. Eliezer is trying to lead them to conclude that any such tablet being authoritative just by nature is absurd and only seems right because they expect the tablet to agree with them. Another method is asking why the tablet says what it does. Asking if God's decrees are arbitrary or if there is a good reason, ask why not just follow those reasons.
That was always a confused argument. A universally compelling argument is supposed to compell any epistemically rational agent. The fact that it doesn't compel a paperclipper, or a rock is irrelevant.