cousin_it comments on The prior of a hypothesis does not depend on its complexity - Less Wrong

26 Post author: cousin_it 26 August 2010 01:20PM

You are viewing a comment permalink. View the original post to see all comments and the full post content.

Comments (59)

You are viewing a single comment's thread. Show more comments above.

Comment author: Spurlock 26 August 2010 02:17:54PM 2 points [-]

Can you elaborate on how it might defuse Pascal's Mugging? It seems the problem there is that, no matter how low your prior, the mugger can just increase the number of victims until the expected utility of paying up overwhelms that of not paying. Hypothesis complexity doesn't seem to play in, and even if I were using it to assign a low prior, this could still be overcome.

That said, any solution to the problem (Robin's of course being a good start) is more than welcome.

Comment author: cousin_it 26 August 2010 02:42:34PM 0 points [-]

Not sure. I must've gone crazy for a minute there, thinking something like "being able to influence 3^^^^3 people is a huge conjunction of statements, thus low probability" - but of course the universal prior doesn't work like that. Struck that part.

Comment author: Manfred 02 January 2012 06:54:44AM 0 points [-]

It still seems relevant to me, since like in the "if my brother's wife's first son's best friend flips a coin, it will fall heads" example, the prior probability actually comes from opening up the statement and looking inside, in a way that would also differentiate just fine between stubbing 3 toes and stubbing 3^3^3 toes.

Comment author: Vladimir_Nesov 26 August 2010 03:05:12PM *  0 points [-]

Question: can we construct a low-complexity event that has universal prior much lower than is implied by its complexity, in other words it describes a relatively small set of programs, each of which has high complexity? Clearly it can't just describe one program, but maybe with a whole set of them it's possible. Naturally, the programs must be still hard-to-locate given the event.

Comment deleted 26 August 2010 03:09:50PM *  [-]
Comment author: Vladimir_Nesov 26 August 2010 03:13:33PM *  0 points [-]

K-complexity of the program defined by that criterion is about as low as that of the criterion, I'm afraid, so example 2 is invalid ("complexity" that is not K-complexity shouldn't be relevant). The universal prior for that theory is not astronomically low.

Edit: This is wrong, in particular because the criterion doesn't present an algorithm for finding the program, and because the program must by definition have high K-complexity.

Comment author: cousin_it 26 August 2010 03:22:28PM *  0 points [-]

Um, what? Can you exhibit a low-complexity algorithm that predicts sensory inputs in accordance with the theory from example 2? That's what it would mean for the universal prior to not be low. Or am I missing something?

Comment author: Vladimir_Nesov 26 August 2010 04:17:40PM *  0 points [-]

You are right, see updated comment.