# ChrisHallquist comments on How to Fix Science - Less Wrong

45 07 March 2012 02:51AM

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Comment author: 04 March 2012 01:35:51AM 7 points [-]

The problem is that philosophers also make poor philosophers.

Less snarkily, "logical inference" is overrated. It does wonders in mathematics, but rarely does scientific data logically require a particular conclusion.

Comment author: 04 March 2012 04:34:21AM -2 points [-]

Well, of course one cannot logically and absolutely deduce much from raw data. But with some logically valid inferential tools in our hands (Occam's razor, Bayes' Theorem, Induction) we can probabilistically derive conclusions.

Comment author: 04 March 2012 04:51:13AM 2 points [-]

In what sense Occam's razor "logically valid"?

Comment author: 04 March 2012 05:29:45AM 0 points [-]

Well, it is not self-contradictory, for one thing. For another thing, every time a new postulate or assumption is added to a theory we are necessarily lowering the prior probability because that postulate/assumption always has some chance of being wrong.

Comment author: 04 March 2012 05:28:11PM 3 points [-]

Just to clarify something: I would expect most readers here would interpret "logically valid" to mean something very specific - essentially something is logically valid if it can't possibly be wrong, under any interpretation of the words (except for words regarded as logical connectives). Self-consistency is a much weaker condition than validity.

Also, Occam's razor is about more than just conjunction. Conjunction says that "XY" has a higher probability than "XYZ"; Occam's razor says that (in the absence of other evidence), "XY" has a higher probability than "ABCDEFG".

Comment author: 05 March 2012 11:31:35PM -2 points [-]

Hi Giles,

I think Occam's razor is logically valid in the sense that, although it doesn't always provide the correct answer, it is certain that it will probably provide the correct answer. Also, I'm not sure if I understand your point about conjunction. I've always understood "do not multiply entities beyond necessity" to mean that, all else held equal, you ought to make the fewest number of conjectures/assumptions/hypotheses possible.