eli_sennesh comments on Probability and radical uncertainty - Less Wrong

11 Post author: David_Chapman 23 November 2013 10:34PM

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Comment author: RichardKennaway 24 November 2013 09:43:30AM 5 points [-]

This is now a situation of radical uncertainty.

The Bayesian Universalist answer to this would be that there is no separate meta-probability. You have a universal prior over all possible hypotheses, and mutter a bit about Solomonoff induction and AIXI.

I am putting it this way, distancing myself from the concept, because I don't actually believe it, but it is the standard answer to draw out from the LessWrong meme space, and it has not yet been posted in this thread. Is there anyone who can make a better fist of expounding it?

Comment author: David_Chapman 24 November 2013 06:44:56PM 2 points [-]

Yes, I'm not at all committed to the metaprobability approach. In fact, I concocted the black box example specifically to show its limitations!

Solomonoff induction is extraordinarily unhelpful, I think... that it is uncomputable is only one reason.

I think there's a fairly simple and straightforward strategy to address the black box problem, which has not been mentioned so far...

Comment author: [deleted] 24 November 2013 11:34:10PM *  2 points [-]

Solomonoff induction is extraordinarily unhelpful, I think... that it is uncomputable is only one reason.

Because it's output is not human-readable being the other?

I mean, even if I've got a TARDIS to use as a halting oracle, an Inductive Turing Machine isn't going to output something I can actually use to make predictions about specific events such as "The black box gives you money under X, Y, and Z circumstances."

Comment author: David_Chapman 25 November 2013 12:13:14AM *  2 points [-]

Well, the problem I was thinking of is "the universe is not a bit string." And any unbiased representation we can make of the universe as a bit string is going to be extremely large—much too large to do even sane sorts of computation with, never mind Solomonoff.

Maybe that's saying the same thing you did? I'm not sure...

Comment author: torekp 26 November 2013 05:56:43PM 4 points [-]

Can you please give us a top level post at some point, be it in Discussion or Main, arguing that "the universe is not a bit string"? I find that very interesting, relevant, and plausible.

Comment author: David_Chapman 26 November 2013 08:08:49PM 1 point [-]

Thanks for the encouragement! I have way too many half-completed writing projects, but this does seem an important point.