Rationality Quotes: February 2010

wedrifid

A monthly thread for posting rationality-related quotes you've seen recently (or had stored in your quotesfile for ages).

Please post all quotes separately, so that they can be voted up/down separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)
Do not quote yourself.
Do not quote comments/posts on LW/OB.
No more than 5 quotes per person per monthly thread, please.

ETA: It would seem that rationality quotes are no longer desired. After several days this thread stands voted into the negatives. Wolud whoever chose to to downvote this below 0 would care to express their disapproval of the regular quotes tradition more explicitly? Or perhaps they may like to browse around for some alternative posts that they could downvote instead of this one? Or, since we're in the business of quotation, they could "come on if they think they're hard enough!"

A monthly thread for posting rationality-related quotes you've seen recently (or had stored in your quotesfile for ages).

Please post all quotes separately, so that they can be voted up/down separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)
Do not quote yourself.
Do not quote comments/posts on LW/OB.
No more than 5 quotes per person per monthly thread, please.

Splat: Thanks for this; it's enlightening and useful.

The part I'm not convinced of this:

to simulate any biological creature, you need N plus a bunch of biological information

A squirrel is a finite structure; it can be specified by a sequence of A's, C's, G's and T's, plus some rules for protein synthesis and a finite number of other facts about chemistry. (Or if you think that leaves something out, it can be described by the interactions among a large but finite collection of atoms.) So I don't see where we need all of N to simulate a squirrel.

Well, if you need to simulate a squirrel for just a little while, and not for unbounded lengths of time, a substructure of N (without closure under the operations) or a structure with a considerable amount of sharing with N (like 64-bit integers on a computer) could suffice for your simulation.

The problem you encounter here is that these substructures and near-substructures, once they reach a certain size, actually require more information to specify than N itself. (How large this size is depends on which abstract computer you used to define your instance... (read more)

-2SilasBarta16y

Okay, pretend I've given you the axioms sufficient for you to +-*/. Can simulate squirrels now? Of course not. You still have to go out and collect information about squirrels and add it to your description of the axioms of arithmetic (which suffice for all of N) to have a description of squirrels. You claim that because you can simulate squirrels with (a part of) N, then N suffices to simulate squirrels. But this is like saying that, because you know the encoding method your friend uses to send you messages, you must know the content of all future messages. That's wrong, because those are different parts of the compressed data: one part tells you how to decompress, another tells you what you're decompressing. Knowing how to decompress (i.e., the axioms of N) is different from knowing the string to be decompressed by that method (i.e. the arithmetic symbols encoding squirrels). By the way, I really hope your remark about Splat's comment being "enlightening" was just politeness, and that you didn't actually mean it. Because if you did, that would mean you're just now learning the distinction between N and T(N), the equivocation between which undermines your claims about arithmetic's relation to the universe. And much of his comment was a restatement of my point about the difference between the complex arithmetic you refer to, and the arithmetic the universe actually runs on. (I'm not holding my breath for a retraction or a mea culpa or anything, just letting people know what they're up against here.)