"Reason" does not appear to be the right term here. "Cleverness" comes to mind as a better substitute, though I suspect there are better terms. The banking crisis occurred because people thought they were too clever. The various problematic causes you mention all appear to overestimate their own cleverness. It's also unclear to me what it would mean for them to rely on reason less, and how this would cause their worldview to better match reality.

I think this might be best phrased as an objection to an overreliance on clever theories and a tendency to eschew evidence in favor of cleverness. Insofar as that is your point, it is an excellent if not novel one. But the way this is phrased is a bit more antagonistic than I think is merited, and seems to attack a type of thought rather than a specific error that a type of thought is prone to.

If my semantic distinction does not make sense, let me just explain my connotations. When I hear "reason," I tend to think of it much like "rational;" one definitionally cannot make a mistake through being too rational, in that rationality is the thing that having more of it causes you not to make mistakes. "Cleverness," on the otherhand, brings the same intellectual sleight-of-hand without any connotation of accuracy. The sentence, "Bob lost all his money because he was too reasonable," does not really make sense, whereas, "Bob lost all of his money because he was too clever," does. A good example of being too clever would be the demise of Vizzini from the Princess Bride.

My main argument is that most likely none of us really knows enough about mathematics of quantum mechanics to follow emergence of patterns of observable universe out of MWI. My quantum maths stops at quantum computing, which is MWI-interpretable, and Copenhagen-interpretable equally well.

The second argument is that our view of physics is incomplete - we don't know about quantum gravity, our cosmology is ridiculous, filled with inflation, dark matter, dark energy etc., we don't know if there are any tiny non-linearities in 200th decimal place with quantum systems (no physical law so far withstood this). MWI completely fails if any such non-linearities are present, while other theories can handle them. Quantum computers are also spectacularly precise quantum effect measurement devices, so we might find that out.

I find the case for MWI decent, but nowhere near as overwhelming as the usual examples of theism and marijuana legalization. It can collapse with one experiment, and I'm not betting against such experiment happening in my lifetime at odds higher than 10:1.

Here's amusing quantum effect to think about

Unless there's akrasia involved. I can only imagine how tempting it would be to just outright buy a house if I were suddenly handed a million dollars, no matter how sternly I told myself not to just outright buy a house.

Another possible sane motivation for taking the $500 is a familiarity with how commonly lottery winners find their lives ruined by the sudden influx of cash.

Solipsism? Isn't there some contradiction inherent in believing in solipsism because someone else tells you that you should?

For me, in just about every case, the credence I'd assign to an AI's wacky claims would depend on its ability to answer followup questions. For instance, in Eliezer's examples:

1) Tin-foil hats actually do block the Orbital Mind Control Lasers

What Orbital Mind Control Lasers? Who uses them? What do they do with them? Why haven't they come up with a way to get around the hats?

2) All mathematical reasoning involving "infinities" involves self-evident contradictions, but human mathematicians have a blind spot with respect to them.

I'm actually strangely comfortable with this one, possibly because I'm bad at math.

3) You are not above-average; most people believe in the existence of a huge fictional underclass in order to place themselves at the top of the heap, rather than in the middle. This is why so many of your friends seem to have PhDs despite PhDs supposedly constituting only 0.5% of the population. You are actually in the bottom third of the population; the other two-thirds have already built their own AIs.

Why haven't I heard of any of these other AIs before? How do all of the people producing statistics indicating that there are a lot of dumb people coordinate their efforts to perpetuate the fiction?

4) The human bias toward overconfidence is far deeper than we are capable of recognizing; we have a form of species overconfidence which denies all evidence against itself. Humans are much slower runners than we think, muscularly weaker, struggle to keep afloat in the water let alone move, and of course, are poorer thinkers.

Why do so few of us die of drowning (or any of the other things that would kill us if we were so dramatically more pathetic than we believe)? If this bias is so pervasive, why can I see these words on the AI's screen, when it seems that I should block them out as with all over evidence that we are pathetic in this way?

5) Dogs, cats, cows, and many other mammals are capable of linguistic reasoning and have made many efforts to communicate with us, but humans are only capable of recognizing other humans as capable of thought.

If we have this incapability, what explains the abundant fiction in which nonhuman animals (both terrestrial and non) are capable of speech, and childhood anthropomorphization of animals? Can you teach me to talk to the stray cat in my neighborhood? Why only mammals, not birds and the like? What about people who are actively trying to communicate with animals like gorillas, or are those not capable of communication?

6) Humans cannot reproduce without the aid of the overlooked third sex.

Are they overlooked in the sense that people we can otherwise detect are not recognized as being part of this sex, or in the sense that we literally do not notice the existence of the members of this sex? In the former case, how do so many people manage to reproduce without apparently wanting to or involving third parties? In the latter case, how can I get in touch with these people? By what mechanism are they involved in human reproduction?

7) The Earth is flat.

Are we talking Euclidean spacetime here? What is the explanation for the observations of a spheroid Earth?

8) Human beings are incapable of writing fiction; all supposed fiction you have read is actually true.

In this universe? What about stories with plot holes? I think that I have written fiction in the past; am I in causal contact with the events I describe? When I make an edit that changes the plot, how does that work? What about people who write self-insertions?

I would believe that human cognition is much, much simpler than it feels from the inside -- that there are no deep algorithms, and it's all just cache lookups plus a handful of feedback loops which even a mere human programmer would call trivial.

I would believe that there's no way to define "sentience" (without resorting to something ridiculously post hoc) which includes humans but excludes most other mammals.

I would believe in solipsism.

I can hardly think of any political, economic, or moral assertion I'd regard as implausible, except that one of the world's extant religions is true (since that would have about as much internal consistency as "2 + 2 = 3").

I think you're misreading 'beat'. In the context of a drug deal, being 'beat' is getting less than you paid for. I'm pretty sure the kid was saying that if he didn't do the math properly, he'd be cheated on the transaction - I don't think it was a comment about corporal punishment.

Though I haven't seen the show, so I could be wrong.

ETA: simpleton, below, has cleared it up.

Well, that went down well.

This is not a new phenomenon:

http://bringontheendtimes.files.wordpress.com/2009/02/end-nigh.jpg

Are there any other plausible explanations for the cult of the apocalypse?

The end of the world is, after all, probably the single most repeated incorrect prediction of all time. The world has repeatedly stubbornly refused to end for thousands of years now - and yet for many the clock always seems to stand at five-minutes-to-midnight.

lesswrong.com's web server is in the US but both of its nameservers are in Australia, leading to very slow lookups for me -- often slow enough that my resolver times out (and caches the failure).

I am my own DNS admin so I can work around this by forcing a cache flush when I need to, but I imagine this would be a more serious problem for people who rely on their ISPs' DNS servers.