Ockham's Razor

[Borodog]

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A correct statement of Occam's razor is, "The simplest explanation that fits the data is the most likely to be correct.[/b]



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A number of respondents have said something like this. As I understand it, Occam's razor is not about which theory is more likely to be 'correct'. Occam's razor has nothing to do with how likely a theory is to be true, but instead is a principle that directs us how to choose among theories, on non-empirical grounds, that are equally likely to be true given the evidence.

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I couldn't disagree more. This doesn't even make sense. If the simpler explanation were not more likely to be true, what is the justification for the razor at all? The very point is that they are NOT equally likely to be true given the evidence. Hence the razor.

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No. If one theory is more likely to be true given the evidence, we don't need a heuristic principle like Occam's Razor in order to choose among theories. We can just go by the evidence in that case.

We apply Occam's Razor when we have competing theories each of which is empirically adequate. Since you can't choose among theories in that case based solely on the evidence, we need some other principle to guide theory choice, like Occam's Razor. Occam's Razor is not an empirical principle.

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The bolded part is an incorrect interpolation by you of my statement. You make it seem like I am saying some piece of evidence exists which points to the simpler theory being more likely than the other. That's not what I'm saying. I'm saying that given the same evidence, a simpler theory that adequately explains all that evidence is LITERALLY more likely to be correct than less simple alternatives tha adequately explain that same evidence. This is why parsimony and Occam's Razor are useful in the first place.

I repeat, if the simpler explanation is NOT more likely to be correct, WHAT IS THE JUSTIFICATION OF OCCAM'S RAZOR IN THE FIRST PLACE? The simpler theory requires fewer keystrokes?

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