The Anthropic Principle and Probability

[Anselm33]

There’s an important cosmological argument, the Anthropic Principle, which states we live in a universe finely tuned for carbon-based life. That is to say, the probability that our universe, as it exists in a form suitable for carbon-based life came about randomly, is a number so small that it’s effectively zero. This principle has been interpreted in various ways–as an argument for many universes, or for an intelligent designer. I’m interested in getting a Bayesian probability approach to this–not a “proof” of the existence of God–but to show that everything we know from science is consistent with “In the beginning G-d created…”. I’d be most grateful for any thoughts anyone had on this. (See also home.ptd.net/~rkurland)

 

[hatsoff]

There’s an important cosmological argument, the Anthropic Principle, which states we live in a universe finely tuned for carbon-based life. That is to say, the probability that our universe, as it exists in a form suitable for carbon-based life came about randomly, is a number so small that it’s effectively zero. This principle has been interpreted in various ways–as an argument for many universes, or for an intelligent designer. I’m interested in getting a Bayesian probability approach to this–not a “proof” of the existence of God–but to show that everything we know from science is consistent with “In the beginning G-d created…”. I’d be most grateful for any thoughts anyone had on this. (See also home.ptd.net/~rkurland)

The version I know best comes from Robin Collins, in The Blackwell Companion To Natural Theology (2009). There he argues for what he calls the “restricted principle of indifference” (or restricted PoI), in order to assign probability values. The problem with his approach is that it’s not at all clear what he’s attempting to measure with those values. Probability requires interpretation, and he provides nothing sufficiently unambiguous to go on. Meanwhile, no interpretation I can myself imagine permits him to employ his restricted PoI as he intends.

At least Collins makes an attempt at justifying his probability assignments, though. Most fine-tuning arguments I’ve encountered are put together by non-professionals who don’t understand how probability works, and utterly fail to appreciate the necessity of justifying a given probability distribution.

There are other problems with so-called fine-tuning, but since math is my specialty, the above is what sticks out most for me personally.

 

[Anselm33]

Thanks for your reply and the reference. I was thinking of arguments like those put forward by Richard Jeffrey in “Probability and the Art of Judgment”, in which Bayesian probability is put forth as a rational measure of belief.

 

[JohnDamian]

A random occurrence in an essentially ordered sequence is impossible.

To measure a probability or speculate a probablility on a logical impossibility is absurd.

Furthermore, trying to prove God by any probability itself includes the real possibility that God does not exist, or that essentially created things could occur by themselved; even if this is effectively zero – as such it is absurd.