In a life of thirty-nine years, Blaise Pascal (1623–1662) contributed to projective geometry and the theory of probability, carried out decisive experiments on the vacuum and atmospheric pressure, invented a calculating machine, wrote a polemical work that shaped French prose, the Provincial Letters, and left the fragments of an apology for the Christian religion that he never completed and that posterity knows as the Pensées (“Thoughts”). He is hard to classify: a scientist who limits the reach of scientific reason, a Jansenist Christian who uses arguments from probability, a writer who distrusts rhetoric. This article covers his biography, the central themes of the Pensées, and the reception of the work. The profile of Blaise Pascal gives a summary; the aim here is to go deeper.

1. Life and Science

Pascal was born on 19 June 1623 in Clermont (today Clermont-Ferrand) and died in Paris on 19 August 1662. He lost his mother at three and was educated at home by his father, Étienne Pascal, a magistrate and amateur mathematician, who took him to Paris and introduced him to the scientific circles around Mersenne. At sixteen he wrote the Essay on Conics (1640), which contains the result now called Pascal’s “mystic hexagram” theorem.

In Rouen, where his father worked in the tax administration, Pascal designed from 1642 a mechanical calculating machine, the “Pascaline,” to ease his father’s labor. In 1647 he published New Experiments Concerning the Vacuum, and in 1648 he asked his brother-in-law Florin Périer to repeat Torricelli’s experiment on the Puy de Dôme, showing that the mercury column fell with altitude, which supported the view that atmospheric pressure, not a “horror of the vacuum,” explained the phenomenon. His theoretical results were gathered in the treatises on the equilibrium of liquids and the weight of the mass of the air, published after his death, in 1663.

In 1654 Pascal corresponded with Pierre de Fermat on the “problem of points,” the fair division of an interrupted wager, work generally regarded as one of the founding acts of probability theory. That same year he composed the Treatise on the Arithmetical Triangle, published in 1665, which systematizes the properties of what we now call Pascal’s triangle.

In 1647 Pascal also met René Descartes in Paris, when Descartes visited him. Their relation is marked by disagreement: Descartes defended a subtle matter filling apparently empty space, while Pascal cautiously upheld the possibility of the vacuum. The two represent different conceptions of scientific method, but the deeper contrast concerns the place of reason within the whole of knowledge, as we shall see.

2. Conversion, the Memorial, and Port-Royal

The Pascal family drew close to Jansenism from 1646, and his sister Jacqueline entered the convent of Port-Royal in 1652. Jansenism is the movement associated with the theologian Cornelius Jansen (the Augustinus, 1640) and the abbey of Port-Royal, stressing the Augustinian doctrine of grace, of the corruption of human nature by original sin, and of the need for efficacious grace for salvation (for the Augustinian background, see Augustine: Confessions, Time, and Free Will).

On the night of 23 November 1654, Pascal underwent an intense religious experience that he recorded on a small parchment: the Memorial. The document, which he sewed into the lining of his clothing and which was found after his death, opens with the word “Fire” and invokes the “God of Abraham, God of Isaac, God of Jacob, not of the philosophers and the learned” (Dieu d’Abraham, Dieu d’Isaac, Dieu de Jacob, non des philosophes et des savants). The text is often read as a biographical key to Pascal’s distinction between the God of revelation, met in personal experience, and the God of the philosophers, reached by demonstration; but how to interpret Pascal’s “second conversion,” and its effect on his thought, is disputed among scholars.

3. The Provincial Letters

Between January 1656 and March 1657, Pascal published, under the pseudonym Louis de Montalte, the eighteen Letters Written to a Provincial (Lettres provinciales). The immediate cause was the Sorbonne’s censure of the theologian Antoine Arnauld, a friend of Port-Royal, for his positions on grace. The first letters deal with the theological controversy over sufficient and efficacious grace; from the fifth onward, Pascal attacks the casuistry of Jesuit theologians, accusing them of moral laxity and of adapting doctrine to worldly convenience. The work circulated widely, was condemned by Rome and banned in France, and is recognized, whatever one thinks of the fairness of its accusations, as a landmark of satirical and polemical prose in French. Whether Pascal did justice to the Jesuits remains an open historical question.

4. The Pensées: A Book Never Written

In his last years Pascal conceived an Apology for the Christian Religion meant to persuade the “libertines,” the worldly skeptics of his day. Illness kept him from writing it. What remained were hundreds of papers, partly gathered by him into bundles (liasses) and partly loose. The first edition, prepared by friends at Port-Royal, appeared in 1670 as Thoughts of M. Pascal on Religion and on Some Other Subjects, with the editors’ own selection and arrangement and some softening of the text.

Editions and Numbering

Anyone citing the Pensées must name the edition, because numbering varies:

  • Brunschvicg (first edition 1897): arranges the fragments thematically, in fourteen sections, and was the standard edition for more than half of the twentieth century. Cited as “B.” or “Br.”
  • Lafuma (1951): tries to reconstruct the order of the papers from the first manuscript copy, respecting the bundles Pascal left. Cited as “L.” or “Laf.”
  • Sellier: the critical edition by Philippe Sellier, which adopts another arrangement and numbering (“S.”). For example, the phrase “Descartes useless and uncertain” is cited as S. 445 / L. 887.

In this article we give Brunschvicg numbers (the most widespread in translations and older scholarship) and, where verified, Lafuma’s. The editions do not correspond perfectly in order; check the concordance table of the edition you hold.

5. The Wager (Br. 233 / L. 418)

The best-known fragment of the Pensées is headed “Infinite, nothing” (Infini — rien) and contains Pascal’s wager. It addresses a libertine interlocutor who cannot believe and who claims that reason does not settle the question of God’s existence. The argument can be summarized in steps:

  1. Reason alone cannot decide between “God is” and “God is not”: between us and God lies an infinite distance, and we can know neither his nature nor his existence by natural reason.
  2. Nevertheless, one must wager: it is not a voluntary choice (“you are embarked”), since life itself confronts us with the alternative. Refusing to wager is already a way of wagering against.
  3. Gain and loss are then weighed. If God exists and one believes, one gains an infinitely happy life; if God does not exist, one loses little, something finite. Given a finite chance that God exists and a possible infinite gain, wagering on belief is rational.
  4. To the interlocutor who replies “but I cannot believe,” Pascal suggests acting as believers do, taking holy water, having masses said, so that habit will dispose body and mind toward faith.

Interpreters, following Ian Hacking (1972), discuss the logical structure of the argument, which combines considerations of dominance and of expected value, and see in it one of the first explicit uses of decision theory. The classic objections include the many-gods objection (the wager would work for any deity promising infinite reward, an objection already voiced by Diderot in the Philosophical Thoughts, 1746), the voluntary belief objection (one cannot believe by decision), the infinite utility objection (which breaks the expected-value calculation), and the objection that an interested faith would be inauthentic or unacceptable in God’s eyes. William James, in “The Will to Believe” (1896), judged the argument inadequate as an apology.

Two cautions for readers. First, the wager does not aim to prove God’s existence but to show that uncertainty does not license indifference. Second, it is only one moment of Pascal’s apologetics, aimed at a specific kind of interlocutor; it is a mistake to take it as the author’s complete doctrine of faith (see Philosophy of Religion: Theodicy, Fideism, and Experience).

6. The Spirit of Geometry and the Spirit of Finesse (Br. 1 / L. 512)

In a fragment that opens the Brunschvicg edition, Pascal writes: “There is a great difference between the spirit of geometry and the spirit of finesse” (Il y a beaucoup de différence entre l’esprit de géométrie et l’esprit de finesse). The distinction, which the philosophical tradition would return to many times, can be described thus:

  • In the spirit of geometry, the principles are palpable but remote from common use; whoever is not accustomed to them finds it hard to turn the mind toward them, but if he does, he will see them fully, and only a faulty mind would reason badly from principles so plain. It is the spirit of mathematicians: rigorous deduction from a few principles.
  • In the spirit of finesse (the term is usually left in French, since “subtlety” or “delicacy” does not capture it), the principles are in common use and before everyone’s eyes; there is no need to turn the head, but good sight is required, because they are so numerous and so fine that it is almost impossible not to miss some. It is the spirit of judgment, which grasps a multitude of elements at a stroke, as in judging a person’s character.

Each is dangerous when it invades the other’s territory: the geometer, accustomed to demonstration, cannot judge by feeling; the man of finesse tries to treat with mathematical demonstration what does not belong to it. Pascal, himself a geometer, does not despise geometry; he delimits its scope. The opuscule On the Geometrical Spirit and On the Art of Persuasion (composed around 1655 and published posthumously) complements the point, holding that geometry is the most perfect method of demonstration but cannot define all terms or prove all principles, and that its first principles are known in another way.

7. The Heart and Its Reasons (Br. 277 and 282)

In this context Pascal writes the most quoted, and most misunderstood, sentence of the Pensées: “The heart has its reasons which reason does not know” (Le cœur a ses raisons que la raison ne connaît point; Br. 277). It is neither a defense of emotion against intellect nor irrationalism. In another fragment (Br. 282 / L. 110), Pascal says we know truth not only by reason but also by the heart, and it is through the latter that we know first principles, the existence of space, time, motion, numbers; reason then rests on them but does not demonstrate them. This is an epistemological thesis: the foundations of demonstrative reasoning are not themselves demonstrable, and the heart names the faculty of grasping these principles intuitively and, in the religious context, of receiving faith as a gift. The critique of extreme skepticism follows: the Pyrrhonists, Pascal says, show the weakness of reason but cannot doubt everything, because the heart knows what reason does not prove. See the discussion in Skepticism: From Pyrrho to Hume.

The position is related to Pascal’s critique of Descartes. In the Pensées we read the formula “Descartes useless and uncertain” (S. 445 / L. 887). Some interpreters understand it as a critique of the uselessness of Cartesian philosophy for salvation; others, such as Daniel Klugman, argue that the criticism also reaches the Cartesian theory of knowledge. For the other side of the debate, see Cogito, Ergo Sum: The Cartesian Foundation and the profile of René Descartes.

8. Misery and Greatness of Man

The anthropological axis of the apology is the double thesis that man is at once miserable and great: miserable, because finite, ignorant, frail, ruled by imagination, self-love, and opinion; great, because he knows himself to be miserable. The human being is thus a contradiction that only the Christian doctrine of the fall and redemption, Pascal argues, explains.

8.1 The Thinking Reed (Br. 347 / L. 200)

“Man is but a reed, the most feeble thing in nature; but he is a thinking reed” (roseau pensant). The universe need not arm itself to crush him: a vapor, a drop of water suffices. But even if the universe crushed him, man would be nobler than what kills him, because he knows that he dies and knows the advantage the universe has over him; the universe knows nothing of this. “All our dignity consists, then, in thought,” and from this comes the moral program: to work at thinking well.

8.2 The Two Infinities (Br. 72)

In the fragment on the “disproportion of man,” Pascal invites the reader to contemplate nature in its immensity and then the smallest of beings, the mite, in whose smallness still smaller worlds open. Man is suspended between the infinitely great and the infinitely small, “a nothing in relation to the infinite, an all in relation to nothing,” unable to grasp the extremes. The passage accompanies the sentence: “The eternal silence of these infinite spaces frightens me” (Br. 206). In later reception the text is often compared, by contrast, with the famous conclusion of Kant’s Critique of Practical Reason (the starry heavens above me and the moral law within me), though this is a parallel drawn by readers and not a demonstrated influence (see Kant: Ethics, Categorical Imperative, and Autonomy and the profile of Immanuel Kant).

8.3 Diversion (Br. 139)

Diversion (divertissement) is the activity by which people turn away from thinking about their condition: hunting, gambling, conversation, war, public office. For Pascal, “all of men’s unhappiness comes from one single thing, which is not knowing how to stay at rest in a room” (tout le malheur des hommes vient d’une seule chose, qui est de ne savoir pas demeurer en repos dans une chambre). Whoever is alone with himself is confronted with his own mortality and emptiness, and boredom exposes him; diversion is an expedient for not looking. Even kings, Pascal observes, need to be diverted, for without distraction they would be unhappy. The analysis goes beyond moral criticism: diversion is, conversely, proof of both human greatness and misery, since it reveals that no finite good satisfies us.

In another fragment Pascal illustrates the contingency of human affairs with Cleopatra’s nose (Br. 162): had it been shorter, the face of the earth would have changed. It is an observation on the weight of small causes in history, set against the pretension of rationality in grand explanations.

9. The Three Orders (Br. 793 / L. 308)

One of the densest texts is that of the three orders: that of bodies, that of minds, and that of charity. Pascal conceives them as separated by infinite distances: the infinite distance between bodies and minds figures the infinitely more infinite distance between minds and charity, which is supernatural. Thus the great ones of the flesh, kings and the rich, mean nothing to minds; great geniuses, such as Archimedes, are invisible to kings but shine in the eyes of the mind; and saints, who belong to the order of charity, are invisible to both but visible to God. Jesus Christ, in this scheme, holds no temporal power and makes no scientific discoveries, yet has the greatness proper to holiness.

Readings diverge. Some see in the doctrine of the orders an affirmation of radical heterogeneity: no quantity of body produces a thought, no quantity of thought produces an act of charity. Others, such as Jean-Luc Marion, read it as subordinating Cartesian metaphysics to charity; still others hold that the fragment states a clash between two conceptions of knowledge. The discussion shows how central and contested the theme is among specialists.

10. Pascal and His Interlocutors

Montaigne. Pascal reads the Essays closely; in the conversation with M. de Sacy on Epictetus and Montaigne (reported in 1655), he contrasts Stoicism, which knows man’s greatness and ignores his misery, with skepticism, which sees the misery and ignores the greatness, and proposes that Christianity unites both truths. Montaigne is at once starting point and adversary (see Montaigne: Essays, Skepticism, and Self-Knowledge and the profile of Michel de Montaigne).

The empiricist tradition. The Pensées owe nothing to the British authors treated in British Empiricism: Locke and Berkeley, but there are points of contact by contrast. Locke, during his stay in France (1675–1679), translated moral essays by Pierre Nicole, who was linked to Port-Royal, and his thesis that reason judges faith and probability recalls Pascal’s attention to decisions under uncertainty, though with different conclusions. Berkeley aims the Alciphron (1732) at the “free-thinkers” of his day, the same worldly types to whom Pascal addresses the wager; but this is only a parallel of context, not a demonstrated influence. On miracles, Hume’s critique (Enquiry Concerning Human Understanding, X, 1748) has as background apologetics such as Pascal’s, which gave weight to miracles (such as that of the Holy Thorn, 1656, tied to Port-Royal); see David Hume: Empiricism, Causation, Induction. See also the profiles of John Locke, George Berkeley, and David Hume.

11. Reception

Voltaire. In the twenty-fifth of the Philosophical Letters (1734), titled “On the Pensées of M. Pascal,” Voltaire attacks the pessimistic view of man: he defends humanity against what he considers melancholy exaggeration and disagrees with Pascal’s disdain for human pleasures and occupations. Voltaire’s criticism fixes one of the terms of the debate: on one side, Pascalian apologetics; on the other, the moderate optimism of the Enlightenment. The profile of Voltaire details the context, and for the counterpart in theodicy see Leibniz and the Monadology.

Kant. The parallel between Pascal’s dismay before the silence of infinite spaces and the conclusion of the second Critique recurs in the literature, though one should not speak of direct influence without textual evidence.

Nietzsche. Nietzsche treated Pascal ambivalently. In The Antichrist (§5) he refers to the corruption of Pascal as the most lamentable example of someone who believed his reason had been corrupted by original sin when, on Nietzsche’s reading, it was Christianity itself that had corrupted him. For context, see Nietzsche: Nihilism and Contemporary Society.

Kierkegaard and the existentialists. The existentialist tradition read in Pascal a precursor of anguish, of the paradox of faith, and of the decisive character of choice, themes associated with Kierkegaard (see Kierkegaard: Stages of Existence and Existentialism). The sociologist and critic Lucien Goldmann, in The Hidden God (1955), proposed a reading that ties Pascal’s “tragic vision” to Jansenism and the social position of the nobility of the robe.

Unamuno. The Spanish thinker Miguel de Unamuno, in whose work faith is inseparable from doubt and from the desire for immortality, is frequently associated by commentators with Pascal and Kierkegaard in the tradition of the “agony” of religious consciousness. See the profile of Miguel de Unamuno.

Decision theory. Probability calculus and the wager make Pascal a precursor invoked by decision theorists and contemporary philosophers of religion.

12. Assessment

Pascal proposes an anthropology in which the human being is defined by contradiction, an epistemology that recognizes a plurality of orders and ways of knowing, and an apologetics addressed to the person who does not know himself a believer. His texts remain in dispute: some read them as fideism, some as moderate rationalism, and some stress the literary dimension. What can be said with confidence is that his delimitation of the domains of reason, heart, and charity influenced the philosophy of religion, French literature, and reflection on the human condition in the centuries that followed.

  • Pensées (posthumous, 1670) — Blaise Pascal (Brunschvicg, Lafuma, and Sellier editions; check the numbering)
  • Provincial Letters (1656–1657) — Blaise Pascal
  • On the Geometrical Spirit and On the Art of Persuasion — Blaise Pascal
  • Conversation with M. de Sacy on Epictetus and Montaigne — Blaise Pascal
  • Voltaire, Philosophical Letters (1734), letter XXV
  • The Hidden God (1955) — Lucien Goldmann
  • The Emergence of Probability (1975) — Ian Hacking
  • Stanford Encyclopedia of Philosophy: entries “Blaise Pascal” and “Pascal’s Wager”

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