God's Number Is Up |
Among a heap of books claiming that science proves God's
existence emerges one that computes a probability of 67 percent
By Michael Shermer
In his 1916 poem "A Coat," William Butler Yeats rhymed: "I
made my song a coat/Covered with embroideries/Out of old mythologies/From
heel to throat."
If faith is tethered to science, what happens when the science
changes?
Unwin rejects most scientific attempts to prove the divine--such
as the anthropic principle and intelligent design--concluding that this "is
not the sort of evidence that points in either direction, for or against."
Instead he employs Bayesian probabilities, a statistical method devised by
18th-century Presbyterian minister and mathematician Reverend Thomas
Bayes. Unwin begins with a 50 percent probability that God exists (because
5050 represents "maximum ignorance"), then applies a modified Bayesian
theorem:
The probability of God's existence after the evidence is considered
is a function of the probability before times D ("Divine Indicator Scale"):
10 indicates the evidence is 10 times as likely to be produced if God exists,
2 is two times as likely if God exists, 1 is neutral, 0.5 is moderately more
likely if God does not exist, and 0.1 is much more likely if God does not
exist. Unwin offers the following figures for six lines of evidence: recognition
of goodness (D = 10), existence of moral evil (D = 0.5), existence of natural
evil (D = 0.1), intranatural miracles (prayers) (D = 2), extranatural miracles
(resurrection) (D = 1), and religious experiences (D = 2).
Plugging these figures into the above formula (in sequence,
where the Pafter figure for the first computation is used for
the Pbefore figure in the second computation, and so on for all
six Ds), Unwin concludes: "The probability that God exists is 67%." Remarkably,
he then confesses: "This number has a subjective element since it reflects
my assessment of the evidence. It isn't as if we have calculated the value
of pi for the first time."
Indeed, based on my own theory of the evolutionary origins of
morality and the sociocultural foundation of religious beliefs and faith,
I would begin (as Unwin does) with a 50 percent probability of God's existence
and plug in these figures: recognition of goodness (D = 0.5), existence of
moral evil (D = 0.1), existence of natural evil (D = 0.1), intranatural miracles
(D = 1), extranatural miracles (D = 0.5), and religious experiences (D =
0.1). I estimate the probability that God exists is 0.02, or 2 percent.
Regardless, the subjective component in the formula relegates
its use to an entertaining exercise in thinking--on par with
mathematical
puzzles--but little more. In my opinion, the question of God's existence
is a scientifically insoluble one. Thus, all such scientistic theologies
are compelling only to those who already believe. Religious faith depends
on a host of social, psychological and emotional factors that have little
or nothing to do with probabilities, evidence and logic. This is faith's
inescapable weakness. It is also, undeniably, its greatest power. |
Michael Shermer is publisher of Skeptic
(www.skeptic.com) and author of The
Science of Good and Evil.
Contact@stephenunwin.com.
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