The First London Rationalist Meetup

Which of you was the Deceiver and what tactics did he use?

I think having someone advocate for the number to be in a particular direction (either high or low) is a more realistic kind of bad faith to learn to defend against.

[-]taw17y60

Julian was the Deceiver and from what he said he was basically trying to add noise to the process. I wonder how one can successfully deceive haveing as little clue about the real answer as everyone else.

[-]JulianMorrison17y40

My main problem was I had so little domain knowledge I couldn't invent any red herrings, let alone realistic ones. The only points where I could throw the result out of whack were those where number guesses were called for - and then I couldn't stray too far from the group too often without giving myself away (and managed to anyhow, Mike says he rumbled me when I estimated Mexicans ate 80% maize).

I got tricked into coming to the defense of what a deceiver ought to do. Heh! Identification and self-justification are powerful.

[-]MichaelHoward17y40

Mike says he rumbled me when I estimated Mexicans ate 80% maize

That made me highly suspicious, but the best evidence was...

I got tricked into coming to the defense of what a deceiver ought to do.

Hehe. No-one seemed to be trying to put the estimate in a particular direction so I tried to make the problem a solution - make fun of Red and spot the reactions. I was still only .85 sure as those were the only 2 good clues.

[-]taw17y10

I wasn't actively trying to find out who was Red. Julian said some weird things like 80% maize calories, but everybody said some weird things every now and then.

[-]MichaelHoward17y20

He hadn't a good reason and stuck to the 80% anyway in a suspiciously out of character way... it's hard to describe. He can take it as a compliment that I expected high standards :-)

[-]taw17y10

I expected everybody to have massive misconceptions about things, so while I believed his 80% maize calories estimate to be completely wrong, he seemed to me like someone who simply doesn't know much about food. For example notice how completely wrong we were about maize yield per square km, surprisingly all in the same direction - that's the kind of mistake that amateurs make often .

Also now that I think of it - our estimate was for weight of corn with cobs. If by any chance one cited by Wikipedia is for corn without cobs, then our first estimate might have been insanely accurate. I don't really have energy to investigate this, but if someone else wants, go ahead.

[-]MichaelHoward17y00

What can I say - it was just a gut feeling! :-) As I said on Saturday, I already knew Julian.

I don't think it was too overconfident for that gut feeling to count as the lesser of two pieces of evidence raising p(RedJulian) from .5 to .85.

[-]marc17y20

I definitely enjoyed the meet up.

In defence of my fairly poor estimate I was unconvinced by the assumption that all the maise in mexico was eaten by mexicans. It seemed that this was an uncontrolled assumption but i felt that i could put reasonable bounds on all the assumptions in the land area estimate (if you're asking, yes, the final answer did fall within my 90-10 bounds :) ).

Hopefully with a bit more notice we can get a few extra people next time but i think it was a great idea to get the ball rolling. Thanks to Tomasz for organising.

[-]gwern15y00

In defence of my fairly poor estimate I was unconvinced by the assumption that all the maise in mexico was eaten by mexicans.

Why does it seem so bad? Food products are the most common products countries defend with tariffs and similar policies, and if Mexico is not self-sufficient then even more reason for all consumption to be local.

[-]Nominull17y20

Maybe I'm missing something here, but isn't the first estimate completely meaningless, since it ignores the possibility of maize import/export? I mean, I know it was closer than the second estimate, but seriously, you guys should have known better than to estimate that half of all of Mexico was used for growing crops.

[-]taw17y10

We discussed imports and exports, and couldn't decide if Mexico was a net importer or exporter, so we went on assumption that most likely imports and exports are small percentage of total maize production and consumption. I stand by this.

50% estimate was quite reasonable based on European land use patterns. I mean - what else would you use all the land lying around for if not food? I would go for lower number now, but it still doesn't strike me as absurd.

[-]badger17y40

From the perspective of someone in the American west, most of it just isn't used for anything. I think 50% of occupied land being used for agriculture is a decent heuristic; it's just that less land is developed for any purpose in North America.

[-][anonymous]12y00

That link is for arable land, not total land.

You can see on Wikipedia that only around 12% of Mexico's land is arable.

LESSWRONG
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LESSWRONG
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The First London Rationalist Meetup

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