Against the Gods: The Remarkable Story of Risk by Peter L. Bernstein

two dice of six sides each (or two throws
of one die) would produce 62 combinations or that three dice would
produce 63 combinations.
    The last letter of the series is dated October 27, 1654. Less than a
month later, Pascal underwent some kind of mystical experience. He
sewed a description of the event into his coat so that he could wear it
next to his heart, claiming "Renunciation, total and sweet." He abandoned mathematics and physics, swore off high living, dropped his old
friends, sold all his possessions except for his religious books, and, a short
while later, took up residence in the monastery of Port-Royal in Paris.
    Yet traces of the old Blaise Pascal lingered on. He established the
first commercial bus line in Paris, with all the profits going to the
monastery of Port-Royal.
    In July 1660, Pascal took a trip to Clermont-Ferrand, not far from
Fermat's residence in Toulouse. Fermat proposed a meeting "to embrace you and talk to you for a few days," suggesting a location halfway
between the two cities; he claimed bad health as an excuse for not
wanting to travel the full distance. Pascal wrote back in August:
    I can scarcely remember that there is such a thing as Geometry [i.e.,
mathematics]. I recognize Geometry to be so useless that I can find
little difference between a man who is a geometrician and a clever
craftsman. Although I call it the best craft in the world it is, after all,
nothing else but a craft .... It is quite possible I shall never think of
it again. 17

    Pascal put together his thoughts about life and religion while he was
at Port-Royal and published them under the title Pensees.'8 In the course
of his work on that book, he filled two pieces of paper on both sides
with what Ian Hacking describes as "handwriting going in all directions
... full of erasures, corrections, and seeming afterthoughts." This fragment has come to be known as Pascal's Wager (le pari de Pascal), which
asks, "God is, or he is not. Which way should we incline? Reason cannot answer."
    Here, drawing on his work in analyzing the probable outcomes of the
game of balla, Pascal frames the question in terms of a game of chance. He
postulates a game that ends at an infinite distance in time. At that moment,
a coin is tossed. Which way would you bet-heads (God is) or tails (God
is not)?
    Hacking asserts that Pascal's line of analysis to answer this question
is the beginning of the theory of decision-making. "Decision theory,"
as Hacking describes it, "is the theory of deciding what to do when it
is uncertain what will happen."19 Making that decision is the essential
first step in any effort to manage risk.
    Sometimes we make decisions on the basis of past experience, out of
experiments we or others have conducted in the course of our lifetime.
But we cannot conduct experiments that will prove either the existence
or the absence of God. Our only alternative is to explore the future consequences of believing in God or rejecting God. Nor can we avert the
issue, for by the mere act of living we are forced to play this game.
    Pascal explained that belief in God is not a decision. You cannot
awaken one morning and declare, "Today I think I will decide to
believe in God." You believe or you do not believe. The decision,
therefore, is whether to choose to act in a manner that will lead to
believing in God, like living with pious people and following a life of
"holy water and sacraments." The person who follows these precepts is
wagering that God is. The person who cannot be bothered with that
kind of thing is wagering that God is not.
    The only way to choose between a bet that God exists and a bet that
there is no God down that infinite distance of Pascal's coin-tossing game
is to decide whether an outcome in which God exists is preferablemore valuable in some sense-than an outcome in which God does not
exist, even though the probability may be only 50-50. This insight is what conducts Pascal down the