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by csee 1693 days ago
What about the argument that our existence is some evidence that a Bayesian estimates of p can't be so small that N p is less than one?

You're focusing on (lack of) evidence for a mechanistic explanation but that's not exhaustive.
1 comments
pfdietz 1693 days ago
The problem there is we don't know the "world" of possibilities from which our existence was drawn. It might be the universe (which I read "observable universe"), or it might be out of a large number of causally disconnected universes, or even other branches of a universal wave function (in a Many Worlds interpretation). The "N" there is not the same as the "N" of "our universe".
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csee 1693 days ago
We know approximately the lower bound of N, which is the approximate number of stars in the observable universe multiplied by an informed estimate of the expected number of planets within the goldilocks zone. That's usually what people mean when they discuss N. N could be that, or it could be much much larger, but I think it's fine to limit the discussion to the lower bound, we still have a huge N to work with.

Also I think you missed my point which is about Bayesian estimation of p, not of N.

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pfdietz 1692 days ago
I ignored the comment about Bayesian estimation because I couldn't turn that comment into something that made any sense. Perhaps you could explain in detail what you meant?
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csee 1692 days ago
Your statements in this thread have assumed we have no info to work with (as far as estimating p goes) because we have no understanding of the mechanisms behind how life came to be. But this ignores the evidence that we are here, which is info that can be used in a Bayesian framework to estimate p. The fact we exist, as well as information about how many billions of years it took for us to evolve, contains significant information about p.
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pfdietz 1690 days ago
I still don't understand. We have no useful lower bound on the probability that life arises, so how does Bayesian reasoning bootstrap to any meaningful lower bound?
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csee 1689 days ago
Who said anything about a lower bound of p? I was talking about a lower bound on N, not a lower bound on p.

Bayesian reasoning (by using the fact that we exist rather than don't exist, as well as other info about our existence, such as how long it took us to evolve) helps us estimate a probability distribution of p, as well as a central tendency estimate.

See e.g. https://www.liebertpub.com/doi/full/10.1089/ast.2019.2149

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