Vaniver comments on Newcomb's Problem and Regret of Rationality - Less Wrong

64 Post author: Eliezer_Yudkowsky 31 January 2008 07:36PM

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

Comments (588)

Sort By: Old

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

Comment author: Vaniver 12 July 2012 04:23:17PM *  0 points [-]

No, P(I'm wrong about something mathematical) is 1-epsilon. P(I'm wrong about this mathematical thing) is often low- like 2%, and sometimes actually 0, like when discussing the intersection of a set and its complement. It's defined to be the empty set- there's no way that it can fail to be the empty set. I may not have complete confidence in the rest of set theory, and I may not expect that the complement of a set (or the set itself) is always well-defined, but when I limit myself to probability measures over reasonable spaces then I'm content.

Comment author: Decius 16 July 2012 05:41:49PM 1 point [-]

So, for some particular aspects of math, you have certainty 1-epsilon, where epsilon is exactly zero?

What you are really doing is making the claim "Given that what I know about mathematics is correct, then the intersection of a set and its complement is the empty set."

Comment author: Vaniver 16 July 2012 07:33:04PM 0 points [-]

I was interpreting "something" as "at least one thing." Almost surely my understanding of mathematics as a whole is incorrect somewhere, but there are a handful of mathematical statements that I believe with complete metaphysical certitude.

What you are really doing is making the claim "Given that what I know about mathematics is correct, then the intersection of a set and its complement is the empty set."

"Correct" is an unclear word, here. Suppose I start off with a handful of axioms. What is the probability that one of the axioms is true / correct? In the context of that system, 1, since it's the starting point. Now, the axioms might not be useful or relevant to reality, and the axioms may conflict and thus the system isn't internally consistent (i.e. statements having probability 0 and 1 simultaneously). And so the geometer who is only 1-epsilon sure that Euclid's axioms describe the real world will be able to update gracefully when presented with evidence that real space is curved, even though they retain the same confidence in their Euclidean proofs (as they apply to abstract concepts).

Basically, I only agree with this post when it comes to statements about which uncertainty is reasonable. If you require 1-epsilon certainty for anything, even P(A|A), then you break the math of probability.