I wasn't talking about idea X itself, I was talking about the process of thought about idea X, we were discussing how smart EY is, and I used the specific type of thinking about X as a counter example to sanity waterline being raised in any way.

One can think about plumbing wrong, e.g. imagining that pipes grow as part of a pipe plant that must be ripe or the pipes will burst, even though pipes and valves and so on exist and can be thought of correctly, and plumbing is not an invalid idea. It doesn't matter to the argument I'm making, whenever AIs would foom (whenever pipes would burst at N bars). It only matters that the reasons for belief aren't valid, and aren't even close to being valid. (especially for the post-foom state)

edit: Maybe the issue is that the people in the west seem not to have enough proofs in math homeworks early enough. You get bad grades for bad proofs, regardless of whenever things you proved were true or false! Some years of schools make you internalize that well enough. Now, the people whom didn't internalize this, they are very annoying to argue with. They keep asking that you prove the opposite, they do vague reasoning that's wrong everywhere and ask you to pinpoint a specific error, they ask you to tell them the better way to reason if you don't like how they reasoned about it (imagine this for Fermat's last theorem a couple decades ago, or now for P!=NP), they do every excuse they can think of, to disregard what you say on basis of some fallacy.

edit2: or rather, disregard the critique as 'not good enough', akin to disregarding critique on a flawed mathematical proof if the critique doesn't prove the theorem true or false. Anyway, I just realized that if I think that Eliezer is a quite successful sociopath who's scamming people for money, that results in higher expected utility for me reading his writings (more curiosity), than if I think he is a self deluded person and the profitability of belief is an accident.

I agree that this kind of outside view argument doesn't provide absolute certainty. However, it does provide evidence that part of your reasons for believing X are irrational reasons that you're rationalizing. Reduce your probability estimate of X accordingly.

I should also take this occasion as a reminder to think twice the next time I'm inclined to claim that I'm paraphrasing something fairly and yet in such a way that it still sounds silly;

Note, that the formulation presented here is one I came up with on my own while searching for the bayesstructure behind arguments based on the outside view.