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Selfreferencing comments on An Alien God - Less Wrong

80 Post author: Eliezer_Yudkowsky 02 November 2007 06:57AM

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Comment author: Selfreferencing 02 November 2007 01:42:01PM 2 points [-]

Eliezer,

You say: "if you can invent an equally persuasive explanation for any outcome, you have zero knowledge."

You'll want to read Quine on this. Quine thought that for nearly any sufficiently large data set there were an infinite number of theories that could accurately explain it. Now, granted, some theories are better than others, but many theories are harder to compare with others. Here are some examples:

Suppose you have three theoretical values: simplicity, coherence, and accommodation of the data. Different parts of a given scientific community may have distinct value rankings; they may consider some values more important than others. As a result, they end up gravitating towards different classes of theories.

Further, different scientists may start trying to explain different parts of the data than other scientists, leading their theorizing to be path-dependent. This may also change outcomes of belief in ways that are not rationally objectionable.

Even without the above two problems, theoretical ambiguities present themselves all the time in scientific and every day belief.

Given these considerations, I think that your statement above must be wrong. Certainly you can have a justified belief in one equally good explanation over another. And if that belief is true, you have knowledge (if you meet the completely inscrutable fourth condition; and nobody knows what it is.).

You seem to think that if two equally good explanations present themselves to us, the proper response is to claim suspend judgment, or at least take one judgment on board tentatively, making no knowledge claim. I'm not sure that's right. It seems like we could be justified in taking either one as justified in that case. And thus if we believe the proposition (we do), it's justified (it is), it's true (it might be), and it's X (don't ask me; ask Gettier), then you know it. Justification, to my mind, doesn't always select the one and only one best option. You seem to think it does, and so if there isn't one best explanation you don't have justification. Is that what you think?

Comment author: SilasBarta 19 October 2009 09:26:22PM *  2 points [-]

A lot of people, including me, seem to have been brought to this old discussion recently, and I think it's an interesting coincidence that I just today made this comment, which doubles as a response to selfreferencing here.

I would add that "simplicity, coherence, and accommodation of the data" are not independent -- they can all fit into one metric, that of the shortness of the message needed to reproduce the data. Coherence is accounted for by how you have list any contradictions as exceptions to posited rules. Accommodation of the data is accounted for in that you have to reproduce all of the data, via generating algorithm or by restating it. Simplicity, of course, is inherent in the requirement of minimal length.