Psy-Kosh comments on Causal Reference - Less Wrong

30 Post author: Eliezer_Yudkowsky 20 October 2012 10:12PM

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Comment author: Eliezer_Yudkowsky 28 October 2012 05:53:26AM 2 points [-]

(From "The Simple Truth", a parable about using pebbles in a bucket to keep count of the sheep in a pasture.)

“My pebbles represent the sheep!” Autrey says triumphantly. “Your pebbles don’t have the representativeness property, so they won’t work. They are empty of meaning. Just look at them. There’s no aura of semantic content; they are merely pebbles. You need a bucket with special causal powers.”

“Ah!” Mark says. “Special causal powers, instead of magic.”

“Exactly,” says Autrey. “I’m not superstitious. Postulating magic, in this day and age, would be unacceptable to the international shepherding community. We have found that postulating magic simply doesn’t work as an explanation for shepherding phenomena. So when I see something I don’t understand, and I want to explain it using a model with no internal detail that makes no predictions even in retrospect, I postulate special causal powers. If that doesn’t work, I’ll move on to calling it an emergent phenomenon.”

“What kind of special powers does the bucket have?” asks Mark.

“Hm,” says Autrey. “Maybe this bucket is imbued with an about-ness relation to the pastures. That would explain why it worked – when the bucket is empty, it means the pastures are empty.”

“Where did you find this bucket?” says Mark. “And how did you realize it had an about-ness relation to the pastures?”

“It’s an ordinary bucket,” I say. “I used to climb trees with it… I don’t think this question needs to be difficult.”

“I’m talking to Autrey,” says Mark.

“You have to bind the bucket to the pastures, and the pebbles to the sheep, using a magical ritual – pardon me, an emergent process with special causal powers – that my master discovered,” Autrey explains.

Autrey then attempts to describe the ritual, with Mark nodding along in sage comprehension.

“And this ritual,” says Mark, “it binds the pebbles to the sheep by the magical laws of Sympathy and Contagion, like a voodoo doll.”

Autrey winces and looks around. “Please! Don’t call it Sympathy and Contagion. We shepherds are an anti-superstitious folk. Use the word ‘intentionality’, or something like that.”

“Can I look at a pebble?” says Mark.

“Sure,” I say. I take one of the pebbles out of the bucket, and toss it to Mark. Then I reach to the ground, pick up another pebble, and drop it into the bucket.

Autrey looks at me, puzzled. “Didn’t you just mess it up?”

I shrug. “I don’t think so. We’ll know I messed it up if there’s a dead sheep next morning, or if we search for a few hours and don’t find any sheep.”

“But -” Autrey says.

“I taught you everything you know, but I haven’t taught you everything I know,” I say.

Mark is examining the pebble, staring at it intently. He holds his hand over the pebble and mutters a few words, then shakes his head. “I don’t sense any magical power,” he says. “Pardon me. I don’t sense any intentionality.”

“A pebble only has intentionality if it’s inside a ma- an emergent bucket,” says Autrey. “Otherwise it’s just a mere pebble.”

“Not a problem,” I say. I take a pebble out of the bucket, and toss it away. Then I walk over to where Mark stands, tap his hand holding a pebble, and say: “I declare this hand to be part of the magic bucket!” Then I resume my post at the gates.

Autrey laughs. “Now you’re just being gratuitously evil.”

I nod, for this is indeed the case.

“Is that really going to work, though?” says Autrey.

I nod again, hoping that I’m right. I’ve done this before with two buckets, and in principle, there should be no difference between Mark’s hand and a bucket. Even if Mark’s hand is imbued with the elan vital that distinguishes live matter from dead matter, the trick should work as well as if Mark were a marble statue.

(The moral: In this sequence, I explained how words come to 'mean' things in a lawful, causal, mathematical universe with no mystical subterritory. If you think meaning has a special power and special nature beyond that, then (a) it seems to me that there is nothing left to explain and hence no motivation for the theory, and (b) I should like you to say what this extra nature is, exactly, and how you know about it - your lips moving in this, our causal and lawful universe, the while.)

Comment author: Psy-Kosh 28 October 2012 07:03:49AM *  2 points [-]

How, precisely, does one formalize the concept of "the bucket of pebbles represents the number of sheep, but it is doing so inaccurately." ie, that it's a model of the number of sheep rather than about something else, but a bad/inaccurate model?

I've fiddled around a bit with that, and I find myself passing a recursive buck when I try to precisely reduce that one.

The best I can come up with is something like "I have correct models in my head for the bucket, pebbles, sheep, etc, individually except that I also have some causal paths linking them that don't match the links that exist in reality."

Comment author: fubarobfusco 28 October 2012 07:28:47AM *  1 point [-]

See this thread for a discussion. A less buck-passing model is: "This bucket represents the sheep ... plus an error term resulting from this here specific error process."

For instance, if I systematically count two sheep exiting together as one sheep, then the bucket represents the number of sheep minus the number of sheep-pairs erroneously detected as one sheep. It's not enough to say the sheep-detector is buggy; to have an accurate model of what it does (and thus, what its representations mean) you need to know what the bug is.