Take a completely unknown probability, multiply it by 100 billion...

and what do you get? Another completely unknown probability, 100 billion times larger than the first.

What you can't say without knowing the first probability is that the second one must be close to one, right?

Not according to Jesus Diaz: "This means that the chances of life and habitable planets in our galaxy alone is overwhelmingly high. So high that it's impossible to deny that it's out there."

Nope. Having no idea how life arose on earth, we have no idea how probable it is on any other earth-like planet.

3 comments:

  1. (1) yes, a good point.

    A lot of numeric probabilities just have no rational foundation. In order to calculate objective probabilities, you need either

    (1) to run repeated experiments to see and list the outcomes and then see if the relative frequency of outcomes is stable (as in the "relative frequency" approach) to calculate the probability of any one outcome, or

    (2) to construct an a priori probability one would already need a list of the complete set of outcomes (in a sample space) that might arise from the antecedent conditions on the earth before life began to some point afterwards. And not just that, but we must know that all outcomes are equiprobable as well.
    ----

    It is clear nobody can do either of these, and objective probabilities can't be given.

    All such probabilities given for this are just highly subjective epistemic probabilities and the numbers have no significance (I suppose it's an instance of what Mises called case probabilities masquerading as class probabilities).


    (2) "Having no idea how life arose on earth, "

    On the face of it, that statement is clearly wrong.

    There are plausible hypotheses, and a number of these have been confirmed with more and more empirical evidence building up.

    E.g., the RNA world just got some very good evidence in its favour:

    http://www.sciencedaily.com/releases/2013/11/131106131944.htm

    And it's been known for a long time by experiments that organic compounds -- the building blocks of life -- form quite naturally from inorganic compounds in conditions that would have existed on the early earth.

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    Replies
    1. "On the face of it, that statement is clearly wrong."

      Wikipedia lists about 30 competing models for how life arose. I'd say "we have no idea" is a pretty good description of a field in which there are 30 competing models. So on the face of it, my statement is clearly right.

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  2. My personal opinion regarding the question of reality and creation, "we know absolutely nothing".

    I don't mean to be Platonic or absolutist, let's just say that I'm doubtful of the ways of the rest of me.

    Most will not "get" that, but I'm pretty sure that Gene will ...

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