Pascal Blaise (1623–62), French philosopher known for his brilliance as a mathematician, physicist, inventor, theologian, polemicist, and French prose stylist. Born at Clermont-Ferrand in the Auvergne, he was educated by his father, Étienne, and first gained note for his contribution to mathematics when at sixteen he produced, under the influence of Desargues, a work on the projective geometry of the cone. This was published in 1640 under the title Essai pour les coniques and includes what has since become known as Pascal’s theorem. Pascal’s other mathematical accomplishments include the original development of probability theory, worked out in correspondence with Fermat, and a method of infinitesimal analysis to which Leibniz gave credit for inspiring his own development of the calculus. Pascal’s early scientific fame rests also on his work in physics, which includes a treatise on hydrostatics (Traités de l’équilibre des liqueurs et de la pesanteur de la masse de l’air) and his experiments with the barometer, which attempted to establish the possibility of a vacuum and the weight of air as the cause of the mercury’s suspension.
Pascal’s fame as a stylist rests primarily on his Lettres provinciales (1656–57), which were an anonymous contribution to a dispute between the Jansenists, headed by Arnauld, and the Jesuits. Jansenism was a Catholic religious movement that emphasized an Augustinian position on questions of grace and free will. Pascal, who was not himself a Jansenist, wrote a series of scathing satirical letters ridiculing both parlance since Montaigne. While these arguments were originally raised in order to deny the possibility of knowledge, Pascal, like Descartes in the Meditations, tries to utilize them toward a positive end. He argues that what skepticism shows us is not that knowledge is impossible, but that there is a certain paradox about human nature: we possess knowledge yet recognize that this knowledge cannot be rationally justified and that rational arguments can even be directed against it (fragments 109, 131, and 110). This peculiarity can be explained only through the Christian doctrine of the fall (e.g., fragment 117). Pascal extends his skeptical considerations by undermining the possibility of demonstrative proof of God’s existence. Such knowledge is impossible on philosophical grounds because such a proof could be successful only if an absurdity followed from denying God’s existence, and nature furnishes us with no knowledge incompatible with unbelief (fragments 429 and 781). Furthermore, demonstrative proof of God’s existence is incompatible with the epistemological claims of Christianity, which make God’s personal agency essential to religious knowledge (fragments 460, 449). Pascal’s use of skepticism and his refusal to admit proofs of God’s existence have led some commentators, like Richard Popkin (‘Fideism,’ 1967) and Terence Penelhum (‘Skepticism and Fideism,’ 1983) to interpret Pascal as a fideist, i.e., one who denies that religious belief can be based on anything other than pragmatic reasons. But such an interpretation disregards Pascal’s attempts to show that Christian belief is rational because of the explanatory power of its doctrines, particularly its doctrine of the fall (e.g., fragments 131, 137, 149, 431, 449, and 482). These purported demonstrations of the explanatory superiority of Christianity prepare the way for Pascal’s famous ‘wager’ (fragment 418).
The wager is among the fragments that Pascal had not classified at the time of his death, but textual evidence shows that it would have been included in Section 12, entitled ‘Commencement,’ after the demonstrations of the superior explanatory power of Christianity. The wager is a direct application of the principles developed in Pascal’s earlier work on probability, where he discovered a calculus that could be used to determine the most rational action when faced with uncertainty about future events, or what is now known as decision theory. In this case the uncertainty is the truth of Christianity and its claims about afterlife; and the actions under consideration are whether to believe or not. The choice of the most rational action depends on what would now be called its ‘expected value.’ The expected value of an action is determined by (1) assigning a value, s, to each possible outcome of the action, (2) subtracting the cost of the action, c, from this value, and (3) multiplying the difference by the probability of the respective outcomes and adding these products together. Pascal invites the reader to consider Christian faith and unbelief as if they were acts of wagering on the truth of Christianity. If one believes, then there are two possible outcomes – either God exists or not. If God does exist, the stake to be gained is infinite life. If God does not exist, there are no winnings. Because the potential winnings are infinite, religious belief is more rational than unbelief because of its greater expected value.
The wager has been subjected to numerous criticisms. William James argued that it is indecisive, because it would apply with equal validity to any religion that offers a promise of infinite rewards (The Will to Believe, 1897). But this ignores Pascal’s careful attempt to show that only Christianity has adequate explanatory power, so that the choice is intended to be between Christianity and unbelief. A stronger objection to the wager arises from contemporary work in decision theory that prohibits the introduction of infinite values because they have the counterintuitive result of making even the slightest risk irrational. But while these objections are valid, they do not refute Pascal’s strategy in the Pensées, in which the proofs of Christianity’s explanatory power and the wager have only the preliminary role of inducing the reader to seek the religious certainty that comes only from a saving religious experience which he calls ‘inspiration’ (fragments 110, 381, 382, 588, 808). See also DECISION THEORY, PHILOSOPHY OF RELIGION , PROBABILIT. D.F.