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.
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”.
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.
In what sense Occam’s razor “logically valid”?
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.
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”.
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.