The Probability of God: A Simple Calculation That Proves the Ultimate Truth Book

Using Bayesian probability, physicist Stephan Unwin attempts to show "The Probability of God". He does a far better job of explaining Bayesian probability than all the Christian apologists I have ever seen, so most people won't have a problem understanding the calculations in rest of the book. (and understanding them correctly)

Unwin starts off with an unsubstantiated a priori probability that God exists of 0.5, then at the end triumphantly declares the probability God exists lies around 0.6. Therefore, it is more probable than not. The first problem lies in his a priori probability of 0.5, in that he claims it is just as likely that God exists as not. He doesn't provide anything of substance to support his claim other than more or less a feeling that it should be equally for and against. To me, this is just as intuitive as saying the proof of God is self-evident by simply looking at the world around us. While Unwin does not make this exact claim, an a priori probability of 0.5 is certainly not supported. (either by Unwin or at all)

One by one, he addresses various aspects of the world and assigns a probality for the existance of God based on these aspects. Combined with the previously calculated probability he arrives at a new probability before moving on to the next topic. In the end, he reaches a probability high enough to maintain that it is probable God exists. Like the a priori probability, the values Unwin choose are arbitrary. Admittedly, most are supported, but the supporting evidence also makes a number of assumptions that one should not blindly accept. It is clear that Unwin is a believer and is "stacking the deck" in favor of a higher probability. (consciously or not)

The reason I am giving this 5 stars is that despite these (in my opinion) incorrect assumptions, Unwin does a fantastic job of explaining the process of deciding the how much a particular aspect supports the probability of God and explaining how this effects the final probability. I most certainly reached a far different conclusion thatn Dr. Unwin, but the methodology he used is completely sound. Despite the apparently bias towards a high probability, it is definitely not as blatant as others (e.g. Richard Swinburne). In reaching a different destination, it was fascinating to have Dr. Unwin accompany me on the journey.

If this is topic you are interested in, I cannot recommend this book enough. It is well-written and is flavored with a style of humor that I find extremely enjoyable. Douglas Adams would be proud.