Click this link for TOPICAL INDEX OF POSTS

About Me

No longer take comments. Post's 'labels' are unreliable for linking or searching. Use the INDEX OF POSTS instead. A fairly accurate, but incomplete INDEX of Posts & good overview and understanding of this blog READ SOME REASONS TO REJECT ORTHODOX JUDAISM my April 2014 post or click link above. Born into an Orthodox Jewish family (1950's) and went to Orthodox Yeshiva from kindergarten thru High School plus some Beis Medrash.Became an agnostic in my 20's and an atheist later on. My blog will discuss the arguments for god and Orthodox Judaism and will provide counter arguments. I no longer take comments. My blog uses academic sources, the Torah, Talmud and commentators to justify my assertions. The posts get updated. IF YOU GET A MESSAGE THAT THE POST IS MISSING - LOOK FOR IT IN THE INDEX or search or the date is found in the address.

Wednesday, January 16, 2019

Fine Tuning Argument (Part II) - Using Probability or Chance

This is a follow up to the Fine Tuning Argument  Proof of God from Fine Tuning (Part I), but I think this can be a stand alone.

Here is one popular version

Premise -   The probability or chance of a Life Permitting Universe, given solely nature (no supernatural, no god(s)), is very very low.

Conclusion: Given our life permitting universe, the  probability of “only nature” is very very low. Thus given  our life permitting universe the probability of supernatural intervention is high. We should invoke the existence of a god fine tuner to explain why our Universe is such that it  permits life.

The Premise  seems very difficult to support, but for the sake of argument I will accept the Premise. Nevertheless, we will see the argument fails.

A Short Digression On Probability

For event A, we denote it’s probability as P(A)

For two events A and B, the Probability of A given B is denoted by P(A/B) and equals P(A and B)/P(B). 

Also, P(B/A)= P(A and B)/P(A)

Notice that in general  P(B/A) does not equal P(A/B).

Rather P(B/A)= P(A/B)*P(B)/P(A).

Thus  if  P(A/B) is very low, it does not follow P(B/A) is very low. If the ratio P(B)/P(A) is very high, then  P(B/A) may not be low and in fact can be quite high.  We will see the importance of this ratio.

Also, P(~B/A)= 1-P(B/A). The symbol ‘~’ means negation or not.}

Clarification of the Fine Tuning Argument in terms of Probability

With the basic probability theory understood, we can state the Premise as follows

Let A be the event Life Permitting Universe

Let B be the event Only Nature

Then the Premise  is P(A/B) is very low. Meaning P(Life Permitting Universe/Only Nature) is very low.  For the sake of argument I am accepting this premise. 

The conclusion can be stated as P(B/A) is very low. Meaning P(Only Nature/Life Permitting Universe) is very low. Thus P(~B/A) is very high. Meaning  P(Supernatural//Life Permitting Universe) is high. That is the conclusion a religious person would like to reach. 

Repudiation of the Argument 

Using probability theory, the conclusion P(Only Nature/Life Permitting Universe) is very low, does not follow from the Premise unless the ratio  P(Only Nature)/P(Life Permitting Universe) is not high.  I could argue the ratio is high. There are very few Life Permitting Universes according to the Fine Tuning advocates. That would mean P(Life Permitting Universe) is low. That tends to make the ratio P(Only Nature)/P(Life Permitting Universe) towards the higher side. I would argue P(Only Nature) is also on the high side since we have natural explanations for many things, and very little if any evidence for supernatural things. That would also make the ratio towards the high side. So the ratio, P(Only Nature)/P(Life Permitting Universe) can be argued to be high. It follows  we cannot conclude P(Only Nature / Life Permitting Universe) is low even though P(Life Permitting Universe / Only Nature) is very low.  Given our Life Permitting Universe we can not use probability to support the notion we need something more than ‘only nature’; that we need G-d. 

An objection can be raised that I cannot really support that the ratio P(Only Nature)/P(Life Permitting Universe) is towards the higher side, or at least high enough to offset the low probability of P(Life Permitting Universe/Only Nature). Then I will argue neither can they support that the ratio is not high. Since they are using the argument to prove something, the burden of proof falls more on them than me and they need to provide good support for their lower chosen ratio.  


Every version of Fine Tuning argument or Design argument (that I am aware of), that uses probability to argue against “nature only” (i.e. to invoke supernatural)  suffers from weak premises, misuses of probability and statistical inference, questionable assumed ‘priors’, begging the question and perhaps other problems. Let the buyer beware.