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LONDON: Does God exist? Physicist says it's two-to-one He does
Ruth Gledhill, Religion Correspondent
THE TIMES
5/7/2004
A BRITISH physicist has calculated that the mathematical probability of God existing is two-to-one in favour.
But even though some scientists might find these odds exceptionally high, Dr Stephen Unwin was surprised. As a committed Christian, his own faith had persuaded him previously that there was a more than 90 per cent chance that God really existed.
Dr Unwin, a graduate of Imperial College, London who studied for his doctorate at Manchester University, used the 200-year-old Bayes' Theorem to calculate that there was a 67 per cent chance that God existed.
He weighed the existence of evil and suffering against miracles, divided into supernatural events and miracles that occur when prayers are answered. He also factored in free will, humankind's innate goodness and sense of morality and the many philosophical arguments both for and against the existence of God.
Bayes' Theorem is named after Thomas Bayes, an 18th-century English mathematician who was also a Presbyterian minister. The theorem emerged in the 20th century after a group of mathematicians decided there must be more to probability than tossing a coin.
Bayesians believe that probability is the level of partial belief that something is true on a scale of nought to one hundred. Dr Unwin, who is now resident in the US having been sent on secondment to the Department of Energy, where he was employed to calculate the probability of nuclear s, has his own consulting company in Columbus, Ohio, where he specialises in risk analysis and risk management.
He spells out his argument for the probability of the existence of God in a new book, The Probability of God: A Simple Calculation that Proves the Ultimate Truth, to be published in the UK on April 30.
The equation calculates "posterior probability" by multiplying "prior probability" by the "likelihood function". This is represented mathematically as P(G|E)=A.P(G).P(E|G). In the equation, G is the proposition that God exists and E is the evidence.
Dr Unwin, 48, said: "Bayes's Theorem works by looking at the evidence around and calculates whether the evidence would be more likely to be produced if the proposition, G, was true or false. I lined up a series of areas of evidence, some in favour of the truth of the proposition and some not in favour."
He said his analysis started from a position of "absolute ignorance" as to whether God existed. "Most people, when they address these things, have an established view and want to eliminate uncertainties. I wanted to go to the areas commonly debated and embrace rather than eliminate the uncertainties."
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