The Ghost of Paley
Posts: 1703
Joined: Oct. 2005
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Ogee:
| Quote | | Err.. you claimed they equivocated, then backpedalled and claimed that the fine-tuning argument is not a statement of probability, and asserted that conditioning on "brittleness" would change the outcome. The demonstration of any of this has apparently been lost in the mail. |
Didn't you understand their proof?
| Quote | Our main theorem
Having understood the previous discussion, and with our notation in hand, it is now easy to prove that the WAP does not support supernaturalism (which we take to be the negation ~N of N). Recall that the WAP can be written as P(F|N&L)=1. Then, by Bayes' theorem [see footnote 2] we have
P(N|F&L) = P(F|N&L)P(N|L)/P(F|L)
= P(N|L)/P(F|L)
>= P(N|L)
where '>=' means "greater than or equal to." The second line follows because P(F|N&L)=1, and the inequality of the third line follows because P(F|L) is a positive quantity less than or equal to 1. (The above demonstration is inspired by a recent article on talk.origins by Michael Ikeda <mmikeda@erols.com>; we have simplified the proof in his article. The message ID for the cited article is <5j6dq8$bvj@winter.erols.com> for those who wish to search for it on dejanews.)
The inequality P(N|F&L)>=P(N|L) shows that the WAP supports (or at least does not undermine) the hypothesis that the universe is governed by naturalistic law. This result is, as we have emphasized, independent of how large or small P(F|N) is. The observation F cannot decrease the probability that N is true (given the known background information that life exists in our universe), and may well increase it.
Corollary: Since P(~N|F&L)=1-P(N|F&L) and similarly for P(~N|L), it follows that P(~N|F&L)<=P(~N|L). In other words, the observation F does not support supernaturalism (~N), and may well undermine it.
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See the bolded part? That means, "the probability that the universe is life friendly given naturalism and the existence of life". "Friendly",as you've already admitted, is defined as life compatible. Oh, here, let me quote the paper:
| Quote | b) Our universe is "life friendly," that is, the conditions in our universe (such as physical laws, etc.) permit or are compatible with life existing naturalistically.
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Now, given those conditions, then the bolded probability equals 1, and cancels just like they said. But what if we add another observation:
B: "The constants that permit life have low tolerances"?
Then the probability becomes P(N|F&L&B) = P(N|F&(L&B))=P(F|N&(L&B))P(N|(L&B))/P(F|(L&B))=P(F|N&L&B)P(N|L&B)/P(F|L&B). Can you cancel now without assuming what you're trying to prove? Remember, you admitted that the coincidences themselves were "observations", and as the authors remind us:
| Quote | | Third, we will show that for any argument to be sound, it must include all background information which is known to be true and which affects (changes) the likelihood. In the present situation, L has this status. This will motivate in a formal way our assertion that we must condition on L. |
Of course, we don't really know if my B truly affects the likelihood, but then you would be reasoning in a circle, since you're assuming brittleness is irrelevant to the problem, which is err....what we're investigating in the first place.
I could be wrong, but insults won't change the likelihood. 
I've laid out my objection as clearly as I can. I'll retract it if you or anyone else shows me where I screwed up, but you need to show the flaws explicitly. Once again, I don't mind being wrong, but I need to see where. Emotives won't work.
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Dey can't 'andle my riddim.
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