Blaise Pascal: Life, Science, and Faith in His Philosophy

A childhood among the mathematicians of Paris

Blaise Pascal was born on 19 June 1623 in Clermont, Auvergne, present-day Clermont-Ferrand. According to the Internet Encyclopedia of Philosophy, he received no traditional schooling: it was his father, himself a mathematician, who taught him everything he knew. That same father took him to Paris, where Pascal joined, at just thirteen, the scientific circle of Marin Mersenne, a gathering of the most active mathematicians of the time.

In that circle Pascal soon showed an unusual gift. In June 1639, at sixteen, he presented a set of theorems in projective geometry that included the property now known as Pascal’s mystic hexagon, and the following year he published the Essay on Conic Sections. These early works apply the scientific method with precocious rigor to a geometric problem, closer to Aristotle in its method than in its subject matter.

The years of science: triangles, probability, and a machine that counts

Between 1642 and 1645 Pascal built the Pascaline, to help his father in his work as a tax collector. According to MacTutor History of Mathematics it took three years to build; according to the Internet Encyclopedia of Philosophy it was the first fully functional mechanical calculator in the world. In 1649 Pascal obtained a royal patent for it, but by 1652 only about fifty prototype units had been made: few sold, and production stopped.

The summer of 1654 brought his most lasting contribution. Through an exchange of five letters with Pierre de Fermat, on two gambling problems known as the problem of points and the problem of dice, Pascal and Fermat together laid the foundations of probability and statistics. In the same years he also worked in physics: by 1647 he believed he had proven the existence of the vacuum, in 1648 he observed that atmospheric pressure decreases with altitude, and in 1653 he wrote the Treatise on the Equilibrium of Liquids, setting out the physical principle now known as Pascal’s law of pressure in liquids. To these works is added the Treatise on the Arithmetical Triangle: Pascal was not the first to study that figure, but MacTutor calls his the most important work ever written on the subject.

Illness and the night of the conversion

According to the Internet Encyclopedia of Philosophy, which reports the testimony of Pascal’s sister, Gilberte, after age eighteen Pascal never had a day free from pain or some form of illness. By age twenty-four his condition had reached the point where he could tolerate only liquid food.

Shortly before his religious experience, according to MacTutor, Pascal came close to dying in a carriage mishap: his startled horses took off on their own, and the carriage ended up hanging over a bridge on the Seine. Not long after, on the night of 23-24 November 1654, between 10:30 p.m. and 12:30 a.m. according to the Internet Encyclopedia of Philosophy, Pascal went through an experience he himself described as dreamlike or ecstatic, and which he interpreted as a religious conversion. He wrote an account of that night in a document known as the Memorial and sewed it into the lining of his coat.

He kept it with him until his death: he died in Paris on 19 August 1662, at age 39, eight years after that night.

According to the Stanford Encyclopedia of Philosophy, the intensity of that experience produced a lasting change in Pascal’s way of life, his intellectual interests, and his personal ambitions. The same source, citing the testimony of Pascal’s brother-in-law, adds that after his conversion Pascal grew detached from scientific pursuits.

Even before then, taught by his father, Pascal had worked out a distinction between knowledge of facts, natural reason, and faith. Between January 1656 and March 1657, under the pseudonym Louis de Montalte, Pascal published eighteen letters, the Lettres provinciales, to defend the Jansenist theologian Antoine Arnauld, who had been accused of heresy. According to the Internet Encyclopedia of Philosophy, their tone ranges from light irony to outright mockery of the Jesuits, and the letters were banned by order of Louis XIV in 1660, placed on the Index, and burned by the Inquisition.

The Pensées: what the work is and what it contains

Pascal published no philosophical work during his lifetime. According to the Stanford Encyclopedia of Philosophy, he began writing, in late 1656, a notebook of reflections that remained unfinished at his death in 1662: it was published only afterward, and became known as the Pensées. The Internet Encyclopedia of Philosophy describes the work, in the form it has reached us, as a collection of fragments, aphorisms, homilies, and short essays, conceived as a defense of the Christian faith addressed to non-believers.

One of the central themes of the Pensées, according to the Internet Encyclopedia of Philosophy, is the dual nature of the human condition: part misery, part greatness. In the work’s most discussed fragment, numbered 418 or 680 depending on the edition scholars use, Pascal compares the choice to believe to a wager: betting on God costs little if one loses, and may be worth an endless gain if one wins, while not betting exposes one to the opposite risk. Elsewhere in the same notebook, Pascal writes that it is the heart that experiences God, describing faith as something felt before it is proven.

Worked example: Pascal’s Wager is widely regarded as an early instance of reasoning about a decision under uncertainty, the same kind of calculation that probability theory, born from his letters with Fermat, had formalized only a few years earlier.

Pascal’s distinction between faith and reason touches on a question already raised, in different terms, by Plato and in his contrast with Aristotle over the relationship between knowledge and reality. A later parallel can be drawn with Kant and his categorical imperative: a method of reasoning far from Pascal’s wager, built on pure reason, yet born of the same underlying question — how far reason alone can go in grounding a choice.