Constant comments on What Evidence Filtered Evidence? - Less Wrong

43 Post author: Eliezer_Yudkowsky 29 September 2007 11:10PM

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Comment author: [deleted] 12 April 2011 01:03:22AM 2 points [-]

Bayesian updating requires competing hypotheses. For E to be evidence for H (H=Darwin's theory), P(H|E) must be greater than P(H), but this is possible only if P(H)<1 to begin with, which means P(~H)>0, where ~H is all the competing hypotheses including creationism taken together (i.e. H2,H3,..., where H=H1). And we are able to update only if we have the value for P(E), because of Bayes' formula. But to know P(E), where P(H)<1, we must know P(E|~H), which requires examination of ~H. Therefore we must investigate creationism.

Of course, being finite beings, we need to be able to leave some hypotheses unexamined. But in principle we ought to examine all. So the question of whether or not to examine creationism is a practical question concerning how to allocate our finite resources. Different people may come to different conclusions.