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Eliezer_Yudkowsky comments on Infinite Certainty - Less Wrong

32 Post author: Eliezer_Yudkowsky 09 January 2008 06:49AM

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Comment author: Eliezer_Yudkowsky 09 January 2008 09:17:06AM 3 points [-]

Huh, I must be slowed down because it's late at night... P(A|A) is the simplest case of all. P(x|y) is defined as P(x,y)/P(y). P(A|A) is defined as P(A,A)/P(A) = P(A)/P(A) = 1. The ratio of these two probabilities may be 1, but I deny that there's any actual probability that's equal to 1. P(|) is a mere notational convenience, nothing more. Just because we conventionally write this ratio using a "P" symbol doesn't make it a probability.

Comment author: pnrjulius 27 May 2012 03:39:37AM 1 point [-]

But it does obey the Kolmogorov axioms (it can't be greater than 1 for instance); that seems important.