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The Probability of Doom

Dieks, Dennis (2001) The Probability of Doom. UNSPECIFIED. (Unpublished)

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    According to the Doomsday Argument the probability of an impending extinction of mankind is much higher than we think. The adduced reason is that in our assignment of probabilities to soon or not so soon doom we have not fully taken into account that we live in the specific year 2001. This is relevant information, because if I consider myself as an arbitrary member of the human race I have a much higher probability of finding myself living in 2001 on the hypothesis of a soon extinction, Doom Soon, than on the hypothesis of Doom Late---according to the latter hypothesis there are so many more years I could have found myself living in. Accordingly, Bayesian reasoning leads to a posterior probability of the Doom Soon hypothesis, after I have taken the evidence of my birth date fully into account, that is much higher than the prior probability. I show that the Argument is nothing but a rather trivial mathematical exercise in the calculation of posterior from prior probabilities; it is only about the relation between these probabilities and is silent about the concrete values these probabilities should have. Nothing in the Argument supports the conclusion its proponents think it supports, namely that Doom Soon is much more probable than we ordinarily think. The Argument is formally valid, but ineffective.

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    Item Type: Other
    Keywords: Doomsday Argument Bayesian updating
    Subjects: General Issues > Confirmation/Induction
    Specific Sciences > Probability/Statistics
    Depositing User: Dennis Dieks
    Date Deposited: 25 Apr 2001
    Last Modified: 07 Oct 2010 11:10
    Item ID: 247
    Public Domain: No

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