SilasBarta comments on Your Strength as a Rationalist - Less Wrong

69 Post author: Eliezer_Yudkowsky 11 August 2007 12:21AM

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Comment author: jimrandomh 09 August 2010 09:13:03PM 3 points [-]

Sticking an adjective in front of the word evidence seems to work. "Evidence" includes things that give you 10^-15 bits of information; on the other hand "good evidence", "usable evidence" and "credible evidence" all imply that the strength of the evidence is at least not exponentially tiny.

Comment author: SilasBarta 09 August 2010 10:01:28PM *  1 point [-]

I thought that "evidence", unmodified, would mean non-trivial evidence; otherwise, everything has to count as evidence because it will have some connection to the hypothesis, however weak. To specify a kind of evidence that includes the 1e-15 bit case, I think you would need to say "weak evidence" or "very weak evidence".

But I'm not the authority on this: How do others here interpret the term "evidence" (in the Bayesian sense) when it's unmodified?

Comment author: thomblake 09 August 2010 10:21:14PM 2 points [-]

I'm sympathetic to both views.

I have encountered a number of disputes that revolve around using these two different senses of the word, and am nonetheless blindsided by them consistently.

I try to always specify the strength of evidence in some sense when using the word. I think when I do use it unmodified I tend to use it in the technical sense (including even weak evidence).

It would be odd if 'evidence' excluded weak evidence, since then 'weak evidence' would be a contradiction in terms, or you could see people arguing things like "When I said 'weak evidence' I didn't mean the 1e-15 bit case, since that's not evidence at all!"

Comment author: jimrandomh 09 August 2010 10:32:21PM 2 points [-]

Hmm. Maybe the strength of the evidence isn't the right thing to use, but rather the confidence with which we know the sign of the correlation.

Comment author: JoshuaZ 09 August 2010 11:16:14PM *  3 points [-]

I would if I were talking to a Bayesian, interpret it as meaning something where a "B is evidence for A" if rough calculation shows that P(A|B) > P(A). I don't generally expect rationalists to even mention individual data points unless P(A|B)/P(A) is large, but if someone else gave the data as an example, then I wouldn't expect it to be necessarily large if a Bayesian referred to as evidence. So for example, I could see a Bayesian asserting that the writing of the Bible is evidence for a global flood some 5000 years ago, but I'd be deeply surprised if a Bayesian brought this up in almost any context because the evidence is so weak (in this case P(A|B)>P(A) but P(A|B)/P(A) is very close to 1).

Comment author: SilasBarta 10 August 2010 08:56:56PM 2 points [-]

I agree, this sounds exactly right to me. Unfortunately, I remember that in a lot of Robin Hanson's earlier OvercomingBias posts, my reaction to them would be, "Yes, B is technically evidence in favor of A, but it's extremely weak -- why even mention it?" For example, Suicide Rock.

(I think I have a picture of one of those somewhere...)