I just meant that there are sound, rational reasons for the initial reply to an extravagant claim being "someone would have noticed".

When it comes to trying to deconvert someone my experience is that the chance of an on the spot concession is 0. If your arguments are good they'll sink in later and leave a small crack in the wall.

I'd like to see it pursued further. where does alcohol fit in your schema?

Geocities Less Wrong

The original The War of the Worlds by H.G. Wells has many similarities to the era's "invasion stories" in which a hostile foreign power (usually Germany or France) launches a very successful surprise invasion of Great Britain. Wells just replaced Germany with Martians.

I mistook your comment as advice for how to avoid being ignored, then.

How does that square with e.g. the fact that the gravity of a spherically symmetric object from the outside is the same as that of the same mass compressed into a point at the same center of gravity?

Well of course it doesn't work. People are irrational. :-)

Question: Who is moderating if Eliezer isn't?

Are you speaking from experience? I wouldn't have expected that tack to work most of the time.

If someone says "The sky has been purple for the past three years" the right response is "I think someone would have noticed". There are however reasonable responses to this. For example, "No one noticed because we're all brains in vats! And I have proof! Look here."

Similarly, I think Wednesday is right to say "Someone would have noticed that God didn't exist." it's just that in this case Aunt Alicorn has a really good response: "Lots of very smart people have noticed, you just haven't met any since you've spent your whole life around people who chose to believe in God or never knew any other option. We've tried to tell your people this but you all get pretty upset when we try. Here is our evidence, x, y, z."

Obviously if you keep repeating "Someone would have noticed." after the dissenter has shown that indeed, people have noticed and that there is good reason for why more people haven't noticed then you're doing it wrong.

This is an oversimplification. A baby which has more than one adult on its side will do better than a baby only being raised by its mother.

May I ask what game?

Aside from outrageousness, another piece of "somebody would have noticed" is the cost of noticing.

I tend to apply a slightly different metric of 'how could I benefit if this were true and I believed it'. One reason I don't put much effort into investigating 9/11 conspiracy theories is that I can't see an obvious way to profit from knowing the truth. Other unlikely claims have more immediately obvious personal utility attached to holding / acting on them (if they are true) despite their lack of widespread acceptance.

Harry Potter and the Methods of Rationality updated on Sunday; it could be that writing that story is filling much of his off time.

Let me offer a real life example where a version of this heuristic seems valid: Fermat claimed to have a proof of what is now called Fermat's Last Theorem (that the equation x^n + y^n =z^n has no solutions in positive integers with n>2). This was finally proven in the mid 90s by Andrew Wiles using very sophisticated techniques. Now, in the 150 or so year period where this problem was a famous unsolved problem, many people, both professional mathematicians and amateurs tried to find a proof. There are still amateurs trying to find a proof that is simpler than Wiles, and ideally find a proof that could have been constructed by Fermat given the techniques he had access to. There's probably no theorem that has had more erroneous proofs presented for it, and likely no other theorem that has had more cranks insist they have a proof even when the flaws are pointed out (cranks are like that). If some new individual shows up saying they have a simple, elementary proof of Fermat's Last Theorem, it is reasonable to assign this claim a very low confidence because someone would have noticed it by now. Since so many people (many of whom are very smart) have been expressly looking for such a proof for a very long time, we can be pretty sure that if such a simple proof existed it would have been found by now.

The "somebody would have noticed'" heuristic thus functions like many other heuristics. In some cases the heuristic will fail. And the heuristic will likely fail more frequently in situations like Wednesday where the individual is either ignorant or surrounded by people who make basic mistakes in rationality. But properly used, the heuristic can still be useful and reliable.

He's writing his book.

In most cases such claims imply different expectations about the future. For example, if I am certain I saw big foot I probably assign a higher probability to the discovery of physical evidence that would confirm its existence than you do. 9/11 truthers should be proposing wagers on the discovery of robust evidence, etc.

You'd probably need some neutral arbiter to adjudicate but that should be relatively easy. Making a wager will convince most people you aren't joking or lying. They might still think you're crazy... but if you aren't you'll make some nice money. Also, this makes the other person internalize the cost of not noticing.

Of course, if everyone thinks you're crazy then all else being equal you probably are crazy. You have to have really good evidence before you can conclude that it's everyone else who is out of their minds (which the contemporary atheist has done).

I've never tried to. Two factors in how much time I give a speaker to explain a superficially unlikely claim are (a) how intelligent they have shown themselves to be in the past and (b) how much I value their acquaintance.

Is Eliezer alive and well? He's not said anything here (or on Hacker News, for that matter) for a month...

I have a (short) essay, 'Drug heuristics' in which I take a crack at combining Bostrom's evolutionary heuristics and nootropics - both topics I consider to be quite LW-germane but underdiscussed.

I'm not sure, though, that it's worth pursuing in any greater depth and would appreciate feedback.