Editor's Choice | Hedge bets on God, go directly to heaven
By Frank Wilson
Inquirer Book Editor
https://registration.realcities.com.../mld/inquirer/entertainment/books/7158613.htm
The Probability of God
A Simple Calculation That Proves the Ultimate Truth
By Stephen D. Unwin
Crown Forum. 259 pp. $22.95
Mathematician and philosopher Blaise Pascal (1623-1662) was perhaps the first thinker to apply probability theory to the question of God's existence. Pascal's Wager, as it is called, is neatly summarized by Stephen D. Unwin in The Probability of God: "It boils down to the position that you should lead a God-pleasing life since if God does exist, then the reward is infinite; whereas, if he doesn't exist, well, what did you really lose?"
Pascal, of course, as Unwin points out, died 40 years before the Rev. Thomas Bayes (1702-1761) was born.
So what?
Well, Bayes, a Presbyterian minister who was also a first-rate mathematician, devised a theorem (which bears his name) that would have enabled Pascal to refine his wager considerably. Pascal began with the assumption that the question of whether or not God exists is a 50-50 toss-up.
But, taking that 50 percent as only a prior probability, one can, using Bayes' theorem, update the wager in terms of degrees of belief. "The beauty of casting degrees of belief in this probabilistic framework," Unwin explains, "is that probability theory then dictates strict, mathematical means of deriving quantitative probabilities based on the evidence that is available."
Unwin trained as a theoretical physicist and began his career doing research in the field of quantum gravity. Thanks to quantum theory, he points out, the universe has come to be understood, not as deterministic, but as probabilistic.
In the '80s, Unwin entered the field of risk analysis: "I became a mathematical analyst of the risks associated with operating complex industrial facilities such as nuclear power plants... . "
How does God enter the picture?
"Whether God exists is a perplexing question," Unwin observes, one "that, if not properly dealt with, could easily consume every waking moment." So his book is offered as "a quick, pragmatic, but definitive analysis, intended to allow me, and any reader who agrees with my reasoning, to get on with life... . We can... incorporate the probability of God into everyday decisions with the comfort of knowing we are behaving rationally, as the numbers dictate."
Like Pascal, Unwin begins with a 50-50 truth probability of what he terms Proposition G. He updates that truth probability in light of six evidentiary areas: the recognition of goodness; the existence of moral evil; the existence of natural evil; intra-natural miracles (for instance, a friend recovers from an illness after you have prayed for him to get well); extra-natural miracles (such as bringing someone dead back to life); and religious experiences.
A numerical value is assigned to each of these areas, by means of what Unwin calls a Divine Indicator Scale: 10 indicates the evidence is much more likely to be produced - 10 times more - if God exists; 2 means it's twice more likely if God exists; 1 means the evidence is God-neutral; 1/2 (0.5) means the evidence is moderately more likely if God does not exist; and 1/10 (0.1) means the evidence is much more likely if God does not exist.
Bearing in mind that this sort of probability analysis necessarily depends on a measure of subjectivity, consider the recognition of goodness: If God exists and has created us in his own image, Unwin notes, "an inevitable consequence is that we would recognize the distinction between good and evil," since good is one of God's defining attributes. So, in a God-created world, the probability that good will be recognized is 100 percent.
Now it would be unreasonable to assume that such recognition would be altogether impossible in a godless world, but it would be less likely. Unwin estimates that a fair probability would be 10 percent. Dividing 10 percent into 100 percent gives you 10 as the first Divine Indicator (D). When this is factored into Bayes' theorem, the result is a 91 percent probability that God exists.
What is the final outcome of the calculations? To give that away would be unfair to Unwin and unfair to prospective readers, because Unwin's book is a pleasantly breezy account of some complicated matters well worth learning about. It is useful, for instance, to know that, in contrast to fuzzy linguistic probabilities ("the probability that my client was nowhere near" the scene of the crime), mathematical probabilities have very clearly defined properties. A fair die, for instance, has "about a 16.7 percent probability... of landing three dots up."
Unwin raises one of the more interesting objections to intelligent design theory: Given that we "lack so much understanding of God," the "engineering notion of intelligent design" seems not only naive but also presumptuous.
Unwin's calculations leave plenty of room for the role of faith (which John Henry Newman shrewdly said meant "being capable of bearing doubt"). And it is interesting that the decisive factor in his computations derives from religious experience. Once again, it seems the best argument for the reality of the divine is the Psalmist's: "Oh, taste and see how good the Lord is."
Worth a flutter at the bookies, maybe.
So what, if God were merely a probability? Hey, no offense ...
