Pascal, Blaise

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Blaise Pascal
Portrait of Pascal in 1691
Born	19 June 1623 Clermont-Ferrand, France
Died	19 August 1662 (aged 39) Paris, France
Father	Étienne Pascal
Relatives	Marguerite Périer (niece) Jacqueline Pascal (sister) Gilberte Périer (sister)

Philosophical work
Era	17th-century philosophy
Region	Western philosophy
School	Cartesianism Jansenism Fideism
Main interests	Theology Mathematics Philosophy Physics
Notable ideas	Probability theory Pascal distribution Pascal's wager Pascal's triangle Pascal's law Pascal's rule Pascal's theorem Pascal's calculator

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"Contradiction is not a sign of falsity, nor the lack of contradiction a sign of truth." (10/28/2024)

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Blaise Pascal (born June 19, 1623, Clermont-Ferrand, France—died August 19, 1662, Paris) was a French mathematician, physicist, religious philosopher, and master of prose. He laid the foundation for the modern theory of probabilities, formulated what came to be known as Pascal’s principle of pressure, and propagated a religious doctrine that taught the experience of God through the heart rather than through reason. The establishment of his principle of intuitionism had an impact on such later philosophers as Jean-Jacques Rousseau and Henri Bergson and also on the Existentialists.

Pascal’s life to the Port-Royal years

Pascal’s father, Étienne Pascal, was presiding judge of the tax court at Clermont-Ferrand. His mother died in 1626, and in 1631 the family moved to Paris. Étienne, who was respected as a mathematician, devoted himself henceforth to the education of his children. While his sister Jacqueline (born in 1625) figured as an infant prodigy in literary circles, Blaise proved himself no less precocious in mathematics. In 1640 he wrote an essay on conic sections, Essai pour les coniques, based on his study of the now classical work of Girard Desargues on synthetic projective geometry. The young man’s work, which was highly successful in the world of mathematics, aroused the envy of no less a personage than the great French Rationalist and mathematician René Descartes.

Between 1642 and 1644, Pascal conceived and constructed a calculating device, the Pascaline, to help his father—who in 1639 had been appointed intendant (local administrator) at Rouen—in his tax computations. The machine was regarded by Pascal’s contemporaries as his main claim to fame, and with reason, for in a sense it was the first digital calculator since it operated by counting integers. The significance of this contribution explains the youthful pride that appears in his dedication of the machine to the chancellor of France, Pierre Seguier, in 1644.

Quick Facts

Born:: June 19, 1623, Clermont-Ferrand, France

Died:: August 19, 1662, Paris (aged 39)

Inventions:: Pascaline

Notable Works:: “Essai pour les coniques”; “Les Provinciales”; “Pensées”; “The Physical Treatises of Pascal”; “Traité du triangle arithmétique”

Subjects Of Study:: Pascal’s principle; Pascal’s theorem; Pascal’s triangle; conic section; cycloid; probability

Blaise Pascal conducting experiments with a mercury barometerBlaise Pascal (center) conducting experiments with a mercury barometer in Paris, engraving from *La Nature*, 1878.

Until 1646 the Pascal family held strictly Roman Catholic principles, though they often substituted l’honnêteté (“polite respectability”) for inward religion. An illness of his father, however, brought Blaise into contact with a more profound expression of religion, for he met two disciples of the abbé de Saint-Cyran, who, as director of the convent of Port-Royal, had brought the austere moral and theological conceptions of Jansenism into the life and thought of the convent. Jansenism was a 17th-century form of Augustinianism in the Roman Catholic Church. It repudiated free will, accepted predestination, and taught that divine grace, rather than good works, was the key to salvation. The convent at Port-Royal had become the center for the dissemination of the doctrine. Pascal himself was the first to feel the necessity of entirely turning away from the world to God, and he won his family over to the spiritual life in 1646. His letters indicate that for several years he was his family’s spiritual adviser, but the conflict within himself—between the world and ascetic life—was not yet resolved. Absorbed again in his scientific interests, he tested the theories of Galileo and Evangelista Torricelli (an Italian physicist who discovered the principle of the barometer). To do so, he reproduced and amplified experiments on atmospheric pressure by constructing mercury barometers and measuring air pressure, both in Paris and on the top of a mountain overlooking Clermont-Ferrand. These tests paved the way for further studies in hydrodynamics and hydrostatics. While experimenting, Pascal invented the syringe and created the hydraulic press, an instrument based upon the principle that became known as Pascal’s principle: pressure applied to a confined liquid is transmitted undiminished through the liquid in all directions regardless of the area to which the pressure is applied. His publications on the problem of the vacuum (1647–48) added to his reputation. When he fell ill from overwork, his doctors advised him to seek distractions; but what has been described as Pascal’s “worldly period” (1651–54) was, in fact, primarily a period of intense scientific work, during which he composed treatises on the equilibrium of liquid solutions, on the weight and density of air, and on the arithmetic triangle: Traité de l’équilibre des liqueurs et de la pesanteur de la masse de l’air (Eng. trans., The Physical Treatises of Pascal, 1937) and also his Traité du triangle arithmétique. In the last treatise, a fragment of the De Alea Geometriae, he laid the foundations for the calculus of probabilities. By the end of 1653, however, he had begun to feel religious scruples; and the “night of fire,” an intense, perhaps mystical “conversion” that he experienced on November 23, 1654, he believed to be the beginning of a new life. He entered Port-Royal in January 1655, and though he never became one of the solitaires, he thereafter wrote only at their request and never again published in his own name. The two works for which he is chiefly known, Les Provinciales and the Pensées, date from the years of his life spent at Port-Royal.

Les Provinciales of Blaise Pascal

Written in defense of Antoine Arnauld, an opponent of the Jesuits and a defender of Jansenism who was on trial before the faculty of theology in Paris for his controversial religious works, Pascal’s 18 Lettres écrites par Louis de Montalte à un provincial deal with divine grace and the ethical code of the Jesuits. They are better known as Les Provinciales (“The Provincial Letters”). They included a blow against the relaxed morality that the Jesuits were said to teach and that was the weak point in their controversy with Port-Royal; Pascal quotes freely Jesuit dialogues and discrediting quotations from their own works, sometimes in a spirit of derision, sometimes with indignation. In the two last letters, dealing with the question of grace, Pascal proposed a conciliatory position that was later to make it possible for Port-Royal to subscribe to the “Peace of the Church,” a temporary cessation of the conflict over Jansenism, in 1668.

The Provinciales were an immediate success, and their popularity has remained undiminished. This they owe primarily to their form, in which for the first time bombast and tedious rhetoric are replaced by variety, brevity, tautness, and precision of style; as Nicolas Boileau, the founder of French literary criticism, recognized, they marked the beginning of modern French prose. Something of their popularity, moreover, in fashionable, Protestant, or skeptical circles, must be attributed to the violence of their attack on the Jesuits. In England they have been most widely read when Roman Catholicism has seemed a threat to the Church of England. Yet they have also helped Catholicism to rid itself of laxity; and, in 1678, Pope Innocent XI himself condemned half of the propositions that Pascal had denounced earlier. Thus, the Provinciales played a decisive part in promoting a return to inner religion and helped to secure the eventual triumph of the ideas set forth in Antoine Arnauld’s treatise De la fréquente communion (1643), in which he protested against the idea that the profligate could atone for continued sin by frequent communion without repentance, a thesis that thereafter remained almost unchallengeable until the French church felt the repercussion of the revocation of the Edict of Nantes (which had granted religious freedom to French Protestants) in 1685. Whereas the Jesuits seemed to represent a Counter-Reformation predominantly concerned with orthodoxy and obedience to ecclesiastical authority, the Provinciales advocated a more spiritual approach, emphasizing the soul’s union with the Mystical Body of Christ through charity.

Further, by rejecting any double standard of morality and the distinction between counsel and precept, Pascal aligned himself with those who believe the ideal of evangelical perfection to be inseparable from the Christian life. Although there was nothing original in these opinions, Pascal nevertheless stamped them with the passionate conviction of a man in love with the absolute, of a man who saw no salvation apart from a heartfelt desire for the truth, together with a love of God that works continually toward destroying all self-love. For Pascal, morality cannot be separated from spirituality. Moreover, his own spiritual development can be traced in the Provinciales. The religious sense in them becomes progressively refined after the first letters, in which the tone of ridicule is smart rather than charitable.

Pensées

Pascal finally decided to write his work of Christian apologetics, Apologie de la religion chrétienne, as a consequence of his meditations on miracles and other proofs of Christianity. The work remained unfinished at his death. Between the summers of 1657 and 1658, he put together most of the notes and fragments that editors have published under the inappropriate title Pensées (“Thoughts”). In the Apologie, Pascal shows the man without grace to be an incomprehensible mixture of greatness and abjectness, incapable of truth or of reaching the supreme good to which his nature nevertheless aspires. A religion that accounts for these contradictions, which he believed philosophy and worldliness fail to do, is for that very reason “to be venerated and loved.” The indifference of the skeptic, Pascal wrote, is to be overcome by means of the “wager”: if God does not exist, the skeptic loses nothing by believing in him; but if he does exist, the skeptic gains eternal life by believing in him. Pascal insists that men must be brought to God through Jesus Christ alone, because a creature could never know the infinite if Jesus had not descended to assume the proportions of man’s fallen state.

The second part of the work applies the Augustinian theory of allegorical interpretation to the biblical types (figuratifs); reviews the rabbinical texts, the persistence of true religion, the work of Moses, and the proofs concerning Jesus Christ’s God-like role; and, finally, gives a picture of the primitive church and the fulfillment of the prophecies. The Apologie (Pensées) is a treatise on spirituality. Pascal was not interested in making converts if they were not going to be saints.

Pascal’s apologetics, though it has stood the test of time, is primarily addressed to individuals of his own acquaintance. To convert his libertine friends, he looked for arguments in their favorite authors: in Michel de Montaigne, in the Skeptic Pierre Charron, in the Epicurean Pierre Gassendi, and in Thomas Hobbes, an English political philosopher. For Pascal, Skepticism was but a stage. Modernist theologians in particular have tried to make use of his main contention, that “man is infinitely more than man,” in isolation from his other contention, that man’s wretchedness is explicable only as the effect of a Fall, about which a man can learn what he needs to know from history. In so doing, they sacrifice the second part of the Apologie to the first, keeping the philosophy while losing the exegesis. For Pascal as for St. Paul, Jesus Christ is the second Adam, inconceivable without the first.

Finally, too, Pascal expressly admitted that his psychological analyses were not by themselves sufficient to exclude a “philosophy of the absurd”; to do so, it is necessary to have recourse to the convergence of these analyses with the “lines of fact” concerning revelation, this convergence being too extraordinary not to appear as the work of providence to an anguished seeker after truth (qui cherche en gémissant).

He was next again involved in scientific work. First, the “Messieurs de Port-Royal” themselves asked for his help in composing the Élements de géométrie; and second, it was suggested that he should publish what he had discovered about cycloid curves, a subject on which the greatest mathematicians of the time had been working. Once more fame aroused in him feelings of self-esteem; but from February 1659, illness brought him back to his former frame of mind, and he composed the “prayer for conversion” that the English clergymen Charles and John Wesley, who founded the Methodist Church, were later to regard so highly. Scarcely capable of regular work, he henceforth gave himself over to helping the poor and to the ascetic and devotional life. He took part intermittently, however, in the disputes to which the “Formulary”—a document condemning five propositions of Jansenism that, at the demand of the church authorities, had to be signed before a person could receive the sacraments—gave rise. Finally a difference of opinion with the theologians of Port-Royal led him to withdraw from controversy, though he did not sever his relations with them.

Pascal died in 1662 after suffering terrible pain, probably from carcinomatous meningitis following a malignant ulcer of the stomach. He was assisted by a non-Jansenist parish priest.

Legacy of Blaise Pascal

At once a physicist, a mathematician, an eloquent publicist in the Provinciales, and an inspired artist in the Apologie and in his private notes, Pascal was embarrassed by the very abundance of his talents. It has been suggested that it was his too concrete turn of mind that prevented his discovering the infinitesimal calculus; and in some of the Provinciales the mysterious relations of human beings with God are treated as if they were a geometrical problem. But these considerations are far outweighed by the profit that he drew from the multiplicity of his gifts; his religious writings are rigorous because of his scientific training; and his love of the concrete emerges no less from the stream of quotations in the Provinciales than from his determination to reject the vigorous method of attack that he had used so effectively in his Apologie.

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Blaise Pascal^[a] (19 June 1623 – 19 August 1662) was a French mathematician, physicist, inventor, philosopher, and Catholic writer.

Pascal was a child prodigy who was educated by his father Étienne Pascal, a tax collector in Rouen. His earliest mathematical work was on projective geometry; he wrote a significant treatise on the subject of conic sections at the age of 16. He later corresponded with Pierre de Fermat on probability theory, strongly influencing the development of modern economics and social science.^{[citation needed]} In 1642, he started some pioneering work on calculating machines (called Pascal's calculators and later Pascalines), establishing him as one of the first two inventors of the mechanical calculator.^[6]^[7]

Like his contemporary René Descartes, Pascal was also a pioneer in the natural and applied sciences. Pascal wrote in defense of the scientific method and produced several controversial results.^{[clarification needed]} He made important contributions to the study of fluids, and clarified the concepts of pressure and vacuum by generalising the work of Evangelista Torricelli. The SI unit for pressure is named for Pascal. Following Torricelli and Galileo Galilei, in 1647 he rebutted the likes of Aristotle and Descartes who insisted that nature abhors a vacuum.

He is also credited as the inventor of modern public transportation, having established the carrosses à cinq sols, the first modern public transport service, shortly before his death in 1662.^[8]

In 1646, he and his sister Jacqueline identified with the religious movement within Catholicism known by its detractors as Jansenism.^[9] Following a religious experience in late 1654, he began writing influential works on philosophy and theology. His two most famous works date from this period: the Lettres provinciales and the Pensées, the former set in the conflict between Jansenists and Jesuits. The latter contains Pascal's wager, known in the original as the Discourse on the Machine,^[10]^[11] a fideistic probabilistic argument for why one should believe in God. In that year, he also wrote an important treatise on the arithmetical triangle. Between 1658 and 1659, he wrote on the cycloid and its use in calculating the volume of solids. Following several years of illness, Pascal died in Paris at the age of 39.

Early life and education

Pascal was born in Clermont-Ferrand, which is in France's Auvergne region, by the Massif Central. He lost his mother, Antoinette Begon, at the age of three.^[12] His father, Étienne Pascal, also an amateur mathematician, was a local judge and member of the "Noblesse de Robe". Pascal had two sisters, the younger Jacqueline and the elder Gilberte.

Move to Paris

In 1631, five years after the death of his wife,^[13] Étienne Pascal moved with his children to Paris. The newly arrived family soon hired Louise Delfault, a maid who eventually became a key member of the family.^{[citation needed]} Étienne, who never remarried, decided that he alone would educate his children.

The young Pascal showed an extraordinary intellectual ability, with an amazing aptitude for mathematics and science.^[14] Etienne had tried to keep his son from learning mathematics; but by the age of 12, Pascal had rediscovered, on his own, using charcoal on a tile floor, Euclid’s first thirty-two geometric propositions, and was thus given a copy of Euclid's Elements.^[15]

Essay on Conics

Particularly of interest to Pascal was a work of Desargues on conic sections. Following Desargues' thinking, the 16-year-old Pascal produced, as a means of proof, a short treatise on what was called the Mystic Hexagram, Essai pour les coniques (Essay on Conics) and sent it — his first serious work of mathematics — to Père Mersenne in Paris; it is known still today as Pascal's theorem. It states that if a hexagon is inscribed in a circle (or conic) then the three intersection points of opposite sides lie on a line (called the Pascal line).

Pascal's work was so precocious that René Descartes was convinced that Pascal's father had written it. When assured by Mersenne that it was, indeed, the product of the son and not the father, Descartes dismissed it with a sniff^{[editorialising]}: "I do not find it strange that he has offered demonstrations about conics more appropriate than those of the ancients," adding, "but other matters related to this subject can be proposed that would scarcely occur to a 16-year-old child."^[16]

Leaving Paris

In France at that time offices and positions could be—and were—bought and sold. In 1631, Étienne sold his position as second president of the Cour des Aides for 65,665 livres.^[17] The money was invested in a government bond which provided, if not a lavish, then certainly a comfortable income which allowed the Pascal family to move to, and enjoy, Paris, but in 1638 Cardinal Richelieu, desperate for money to carry on the Thirty Years' War, defaulted on the government's bonds. Suddenly Étienne Pascal's worth had dropped from nearly 66,000 livres to less than 7,300.^{[citation needed]}

Like so many others, Étienne was eventually forced to flee Paris because of his opposition to the fiscal policies of Richelieu, leaving his three children in the care of his neighbour Madame Sainctot, a great beauty with an infamous past who kept one of the most glittering and intellectual salons in all France. It was only when Jacqueline performed well in a children's play with Richelieu in attendance that Étienne was pardoned. In time, Étienne was back in good graces with the Cardinal and in 1639 had been appointed the king's commissioner of taxes in the city of Rouen—a city whose tax records, thanks to uprisings, were in utter chaos.

Pascaline

In 1642, in an effort to ease his father's endless, exhausting calculations, and recalculations, of taxes owed and paid (into which work the young Pascal had been recruited), Pascal, not yet 19, constructed a mechanical calculator capable of addition and subtraction, called Pascal's calculator or the Pascaline. Of the eight Pascalines known to have survived, four are held by the Musée des Arts et Métiers in Paris and one more by the Zwinger museum in Dresden, Germany, exhibit two of his original mechanical calculators.^[18]

Although these machines are pioneering forerunners to a further 400 years of development of mechanical methods of calculation, and in a sense to the later field of computer engineering, the calculator failed to be a great commercial success. Partly because it was still quite cumbersome to use in practice, but probably primarily because it was extraordinarily expensive, the Pascaline became little more than a toy, and a status symbol, for the very rich both in France and elsewhere in Europe. He also presented the first mechanical calculator to Christina, Queen of Sweden in 1632. ^[19] Pascal continued to make improvements to his design through the next decade, and he refers to some 50 machines that were built to his design.^[20] He built 20 finished machines over the following 10 years.^[21]

Mathematics

Probability

In 1654, prompted by his friend the Chevalier de Méré, Pascal corresponded with Pierre de Fermat on the subject of gambling problems, and from that collaboration was born the mathematical theory of probability.^[22] The specific problem was that of two players who want to finish a game early and, given the current circumstances of the game, want to divide the stakes fairly, based on the chance each has of winning the game from that point. From this discussion, the notion of expected value was introduced. John Ross writes, "Probability theory and the discoveries following it changed the way we regard uncertainty, risk, decision-making, and an individual's and society's ability to influence the course of future events."^[23] Pascal, in the Pensées, used a probabilistic argument, Pascal's wager, to justify belief in God and a virtuous life. However, Pascal and Fermat, though doing important early work in probability theory, did not develop the field very far. Christiaan Huygens, learning of the subject from the correspondence of Pascal and Fermat, wrote the first book on the subject. Later figures who continued the development of the theory include Abraham de Moivre and Pierre-Simon Laplace. The work done by Fermat and Pascal into the calculus of probabilities laid important groundwork for Leibniz's formulation of the calculus.^[24]

Treatise on the Arithmetical Triangle

Pascal's triangle. Each number is the sum of the two directly above it. The triangle demonstrates many mathematical properties in addition to showing binomial coefficients.

Pascal's Traité du triangle arithmétique, written in 1654 but published posthumously in 1665, described a convenient tabular presentation for binomial coefficients which he called the arithmetical triangle, but is now called Pascal's triangle.^[25]^[26] The triangle can also be represented:

	0	1	2	3	4	5	6
0	1	1	1	1	1	1	1
1	1	2	3	4	5	6
2	1	3	6	10	15
3	1	4	10	20
4	1	5	15
5	1	6
6	1

He defined the numbers in the triangle by recursion: Call the number in the (m + 1)th row and (n + 1)th column t_mn. Then t_mn = t_m−1,n + t_m,n−1, for m = 0, 1, 2, ... and n = 0, 1, 2, ... The boundary conditions are t_m,−1 = 0, t_−1,n = 0 for m = 1, 2, 3, ... and n = 1, 2, 3, ... The generator t₀₀ = 1. Pascal concluded with the proof,

t_{mn}={\frac {(m+n)(m+n-1)\cdots (m+1)}{n(n-1)\cdots 1}}.

In the same treatise, Pascal gave an explicit statement of the principle of mathematical induction.^[25] In 1654, he proved Pascal's identity relating the sums of the p-th powers of the first n positive integers for p = 0, 1, 2, ..., k.^[27]

That same year, Pascal had a religious experience, and mostly gave up work in mathematics.

Cycloid

In 1658, Pascal, while suffering from a toothache, began considering several problems concerning the cycloid. His toothache disappeared, and he took this as a heavenly sign to proceed with his research. Eight days later he had completed his essay^[28] and, to publicize the results, proposed a contest.^[29]

Pascal proposed three questions relating to the center of gravity, area and volume of the cycloid, with the winner or winners to receive prizes of 20 and 40 Spanish doubloons. Pascal, Gilles de Roberval and Pierre de Carcavi were the judges, and neither of the two submissions (by John Wallis and Antoine de Lalouvère) were judged to be adequate.^[30] While the contest was ongoing, Christopher Wren sent Pascal a proposal for a proof of the rectification of the cycloid; Roberval claimed promptly that he had known of the proof for years. Wallis published Wren's proof (crediting Wren) in Wallis's Tractus Duo, giving Wren priority for the first published proof.

Physics

Pascal contributed to several fields in physics, most notably the fields of fluid mechanics and pressure. In honour of his scientific contributions, the name Pascal has been given to the SI unit of pressure and Pascal's law (an important principle of hydrostatics). He introduced a primitive form of roulette and the roulette wheel in his search for a perpetual motion machine.^[31]

Fluid dynamics

His work in the fields of hydrodynamics and hydrostatics centered on the principles of hydraulic fluids. His inventions include the hydraulic press (using hydraulic pressure to multiply force) and the syringe. He proved that hydrostatic pressure depends not on the weight of the fluid but on the elevation difference. He demonstrated this principle by attaching a thin tube to a barrel full of water and filling the tube with water up to the level of the third floor of a building. This caused the barrel to leak, in what became known as Pascal's barrel experiment.

Vacuum

By 1647, Pascal had learned of Evangelista Torricelli's experimentation with barometers. Having replicated an experiment that involved placing a tube filled with mercury upside down in a bowl of mercury, Pascal questioned what force kept some mercury in the tube and what filled the space above the mercury in the tube. At the time, most scientists including Descartes believed in a plenum, i. e. some invisible matter filled all of space, rather than a vacuum ("Nature abhors a vacuum)." This was based on the Aristotelian notion that everything in motion was a substance, moved by another substance.^[32] Furthermore, light passed through the glass tube, suggesting a substance such as aether rather than vacuum filled the space.

Following more experimentation in this vein, in 1647 Pascal produced Experiences nouvelles touchant le vide ("New experiments with the vacuum"), which detailed basic rules describing to what degree various liquids could be supported by air pressure. It also provided reasons why it was indeed a vacuum above the column of liquid in a barometer tube. This work was followed by Récit de la grande expérience de l'équilibre des liqueurs ("Account of the great experiment on equilibrium in liquids") published in 1648.

First atmospheric pressure vs. altitude experiment

The Torricellian vacuum found that air pressure is equal to the weight of 30 inches of mercury. If air has a finite weight, Earth's atmosphere must have a maximum height. Pascal reasoned that if true, air pressure on a high mountain must be less than at a lower altitude. He lived near the Puy de Dôme mountain, 4,790 feet (1,460 m) tall, but his health was poor so could not climb it.^[33] On 19 September 1648, after many months of Pascal's friendly but insistent prodding, Florin Périer, husband of Pascal's elder sister Gilberte, was finally able to carry out the fact-finding mission vital to Pascal's theory. The account, written by Périer, reads:

The weather was chancy last Saturday...[but] around five o'clock that morning...the Puy-de-Dôme was visible...so I decided to give it a try. Several important people of the city of Clermont had asked me to let them know when I would make the ascent...I was delighted to have them with me in this great work...
...at eight o'clock we met in the gardens of the Minim Fathers, which has the lowest elevation in town....First I poured 16 pounds of quicksilver...into a vessel...then took several glass tubes...each four feet long and hermetically sealed at one end and opened at the other...then placed them in the vessel [of quicksilver]...I found the quick silver stood at 26" and 3+1⁄2 lines above the quicksilver in the vessel...I repeated the experiment two more times while standing in the same spot...[they] produced the same result each time...
I attached one of the tubes to the vessel and marked the height of the quicksilver and...asked Father Chastin, one of the Minim Brothers...to watch if any changes should occur through the day...Taking the other tube and a portion of the quick silver...I walked to the top of Puy-de-Dôme, about 500 fathoms higher than the monastery, where upon experiment...found that the quicksilver reached a height of only 23" and 2 lines...I repeated the experiment five times with care...each at different points on the summit...found the same height of quicksilver...in each case...^[34]

Pascal replicated the experiment in Paris by carrying a barometer up to the top of the bell tower at the church of Saint-Jacques-de-la-Boucherie, a height of about 50 metres. The mercury dropped two lines. He found with both experiments that an ascent of 7 fathoms lowers the mercury by half a line.^[b] Note: Pascal used pouce and ligne for "inch" and "line", and toise for "fathom".^[35]

In a reply to Étienne Noël, who believed in the plenum, Pascal wrote, echoing contemporary notions of science and falsifiability: "In order to show that a hypothesis is evident, it does not suffice that all the phenomena follow from it; instead, if it leads to something contrary to a single one of the phenomena, that suffices to establish its falsity."^[36]

Blaise Pascal Chairs are given to outstanding international scientists to conduct their research in the Ile de France region.^[37]

Adult life: religion, literature, and philosophy

Religious conversion

In the winter of 1646, Pascal's 58-year-old father broke his hip when he slipped and fell on an icy street of Rouen; given the man's age and the state of medicine in the 17th century, a broken hip could be a very serious condition, perhaps even fatal. Rouen was home to two of the finest doctors in France, Deslandes and de la Bouteillerie. The elder Pascal "would not let anyone other than these men attend him...It was a good choice, for the old man survived and was able to walk again..."^[38] However treatment and rehabilitation took three months, during which time La Bouteillerie and Deslandes had become regular visitors.

Both men were followers of Jean Guillebert, proponent of a splinter group from Catholic teaching known as Jansenism. This still fairly small sect was making surprising inroads into the French Catholic community at that time. It espoused rigorous Augustinism. Blaise spoke with the doctors frequently, and after their successful treatment of his father, borrowed from them works by Jansenist authors. In this period, Pascal experienced a sort of "first conversion" and began to write on theological subjects in the course of the following year.

Pascal fell away from this initial religious engagement and experienced a few years of what some biographers have called his "worldly period" (1648–54). His father died in 1651 and left his inheritance to Pascal and his sister Jacqueline, for whom Pascal acted as conservator. Jacqueline announced that she would soon become a postulant in the Jansenist convent of Port-Royal. Pascal was deeply affected and very sad, not because of her choice, but because of his chronic poor health; he needed her just as she had needed him.

Suddenly there was war in the Pascal household. Blaise pleaded with Jacqueline not to leave, but she was adamant. He commanded her to stay, but that didn't work, either. At the heart of this was...Blaise's fear of abandonment...if Jacqueline entered Port-Royal, she would have to leave her inheritance behind...[but] nothing would change her mind.^[39]

By the end of October in 1651, a truce had been reached between brother and sister. In return for a healthy annual stipend, Jacqueline signed over her part of the inheritance to her brother. Gilberte had already been given her inheritance in the form of a dowry. In early January, Jacqueline left for Port-Royal. On that day, according to Gilberte concerning her brother, "He retired very sadly to his rooms without seeing Jacqueline, who was waiting in the little parlor..."^[40] In early June 1653, after what must have seemed like endless badgering from Jacqueline, Pascal formally signed over the whole of his sister's inheritance to Port-Royal, which, to him, "had begun to smell like a cult."^[41] With two-thirds of his father's estate now gone, the 29-year-old Pascal was now consigned to genteel poverty.

For a while, Pascal pursued the life of a bachelor. During visits to his sister at Port-Royal in 1654, he displayed contempt for affairs of the world but was not drawn to God.^[42]

Memorial

On the 23 of November, 1654, between 10:30 and 12:30 at night, Pascal had an intense religious experience and immediately wrote a brief note to himself which began: "Fire. God of Abraham, God of Isaac, God of Jacob, not of the philosophers and the scholars..." and concluded by quoting Psalm 119:16: "I will not forget thy word. Amen." He seems to have carefully sewn this document into his coat and always transferred it when he changed clothes; a servant discovered it only by chance after his death.^[43] This piece is now known as the Memorial. The story of a carriage accident as having led to the experience described in the Memorial is disputed by some scholars.^[44] His belief and religious commitment revitalized, Pascal visited the older of two convents at Port-Royal for a two-week retreat in January 1655. For the next four years, he regularly travelled between Port-Royal and Paris. It was at this point immediately after his conversion when he began writing his first major literary work on religion, the Provincial Letters.

Literature

In literature, Pascal is regarded as one of the most important authors of the French Classical Period and is read today as one of the greatest masters of French prose. His use of satire and wit influenced later polemicists.

The Provincial Letters

Beginning in 1656–57, Pascal published his memorable attack on casuistry, a popular ethical method used by Catholic thinkers in the early modern period (especially the Jesuits, and in particular Antonio Escobar). Pascal denounced casuistry as the mere use of complex reasoning to justify moral laxity and all sorts of sins. The 18-letter series was published between 1656 and 1657 under the pseudonym Louis de Montalte and incensed Louis XIV. The king ordered that the book be shredded and burnt in 1660. In 1661, in the midst of the formulary controversy, the Jansenist school at Port-Royal was condemned and closed down; those involved with the school had to sign a 1656 papal bull condemning the teachings of Jansen as heretical. The final letter from Pascal, in 1657, had defied Alexander VII himself. Even Pope Alexander, while publicly opposing them, nonetheless was persuaded by Pascal's arguments.

Aside from their religious influence, the Provincial Letters were popular as a literary work. Pascal's use of humor, mockery, and vicious satire in his arguments made the letters ripe for public consumption, and influenced the prose of later French writers like Voltaire and Jean-Jacques Rousseau.

It is in the Provincial Letters that Pascal made his oft-quoted apology for writing a long letter, as he had not had time to write a shorter one. From Letter XVI, as translated by Thomas M'Crie: 'Reverend fathers, my letters were not wont either to be so prolix, or to follow so closely on one another. Want of time must plead my excuse for both of these faults. The present letter is a very long one, simply because I had no leisure to make it shorter.'

Charles Perrault wrote of the Letters: "Everything is there—purity of language, nobility of thought, solidity in reasoning, finesse in raillery, and throughout an agrément not to be found anywhere else."^[45]

Philosophy

Pascal is arguably best known as a philosopher, considered by some the second greatest French mind behind René Descartes. He was a dualist following Descartes.^[46] However, he is also remembered for his opposition to both the rationalism of the likes of Descartes and simultaneous opposition to the main countervailing epistemology, empiricism, preferring fideism.

In terms of God, Descartes and Pascal disagreed. Pascal wrote that "I cannot forgive Descartes. In all his philosophy he would have been quite willing to dispense with God, but he couldn't avoid letting him put the world in motion; afterwards he didn't need God anymore".^[47] He opposed the rationalism of people like Descartes as applied to the existence of a God, preferring faith as "reason can decide nothing here".^[48] For Pascal the nature of God was such that such proofs cannot reveal God. Humans "are in darkness and estranged from God" because "he has hidden Himself from their knowledge".^[49]

He cared above all about the philosophy of religion. Pascalian theology has grown out of his perspective that humans are, according to Wood, "born into a duplicitous world that shapes us into duplicitous subjects and so we find it easy to reject God continually and deceive ourselves about our own sinfulness".^[50]

Philosophy of mathematics

Pascal's major contribution to the philosophy of mathematics came with his De l'Esprit géométrique ("Of the Geometrical Spirit"), originally written as a preface to a geometry textbook for one of the famous Petites écoles de Port-Royal ("Little Schools of Port-Royal"). The work was unpublished until over a century after his death. Here, Pascal looked into the issue of discovering truths, arguing that the ideal of such a method would be to found all propositions on already established truths. At the same time, however, he claimed this was impossible because such established truths would require other truths to back them up—first principles, therefore, cannot be reached. Based on this, Pascal argued that the procedure used in geometry was as perfect as possible, with certain principles assumed and other propositions developed from them. Nevertheless, there was no way to know the assumed principles to be true.

Pascal also used De l'Esprit géométrique to develop a theory of definition. He distinguished between definitions which are conventional labels defined by the writer and definitions which are within the language and understood by everyone because they naturally designate their referent. The second type would be characteristic of the philosophy of essentialism. Pascal claimed that only definitions of the first type were important to science and mathematics, arguing that those fields should adopt the philosophy of formalism as formulated by Descartes.

In De l'Art de persuader ("On the Art of Persuasion"), Pascal looked deeper into geometry's axiomatic method, specifically the question of how people come to be convinced of the axioms upon which later conclusions are based. Pascal agreed with Montaigne that achieving certainty in these axioms and conclusions through human methods is impossible. He asserted that these principles can be grasped only through intuition, and that this fact underscored the necessity for submission to God in searching out truths.

Pensées

Man is only a reed, the weakest in nature, but he is a thinking reed.

— Blaise Pascal, Pensées, No. 200

Pascal's most influential theological work, referred to posthumously as the Pensées ("Thoughts") is widely considered to be a masterpiece, and a landmark in French prose. When commenting on one particular section (Thought #72), Sainte-Beuve praised it as the finest pages in the French language.^[51] Will Durant hailed the Pensées as "the most eloquent book in French prose".^[52]

The Pensées was not completed before his death. It was to have been a sustained and coherent examination and defense of the Christian faith, with the original title Apologie de la religion Chrétienne ("Defense of the Christian Religion"). The first version of the numerous scraps of paper found after his death appeared in print as a book in 1669 titled Pensées de M. Pascal sur la religion, et sur quelques autres sujets ("Thoughts of M. Pascal on religion, and on some other subjects") and soon thereafter became a classic.

One of the Apologie's main strategies was to use the contradictory philosophies of Pyrrhonism and Stoicism, personalized by Montaigne on one hand, and Epictetus on the other, in order to bring the unbeliever to such despair and confusion that he would embrace God.

Last works and death

T. S. Eliot described him during this phase of his life as "a man of the world among ascetics, and an ascetic among men of the world." Pascal's ascetic lifestyle derived from a belief that it was natural and necessary for a person to suffer. In 1659, Pascal fell seriously ill. During his last years, he frequently tried to reject the ministrations of his doctors, saying, "Don't pity me, sickness is the natural state of Christians, because in it we are, as we should always be, in the suffering of evils, in the deprivation of all the goods and pleasures of the senses, free from all the passions that work throughout the course of life, without ambition, without avarice, in the continual expectation of death."^[53]^[54] Desiring to imitate Jesus’ poverty of spirit, in his spirit of zeal and charity, Pascal said if God allowed him to recover from his illness, he would be resolved to "have no other employment or occupation for the rest of my life than the service of the poor."^[55]

Louis XIV suppressed the Jansenist movement at Port-Royal in 1661. In response, Pascal wrote one of his final works, Écrit sur la signature du formulaire ("Writ on the Signing of the Form"), exhorting the Jansenists not to give in. Later that year, his sister Jacqueline died, which convinced Pascal to cease his polemics on Jansenism.

Inventor of public transportation

Pascal's last major achievement, returning to his mechanical genius, was inaugurating one of the first land-based public transport services, the carrosses à cinq sols, a network of horse-drawn multi-seat carriages that carried passengers on five fixed routes. Pascal also designated the operation principles which were later used to plan public transportation; the carriages had a fixed route, fixed price (five sols, hence the name), and left even if there were no passengers.^[56] The lines were not commercially successful, and the last one closed by 1675.^[57] Nonetheless, he has been described as the inventor of public transportation.^[58]

Illness and death

In 1662, Pascal's illness became more violent, and his emotional condition had severely worsened since his sister's death. Aware that his health was fading quickly, he sought a move to the hospital for incurable diseases, but his doctors declared that he was too unstable to be carried. In Paris on 18 August 1662, Pascal went into convulsions and received extreme unction. He died the next morning, his last words being "May God never abandon me," and was buried in the cemetery of Saint-Étienne-du-Mont.^[53]

An autopsy performed after his death revealed grave problems with his stomach and other organs of his abdomen, along with damage to his brain. Despite the autopsy, the cause of his poor health was never precisely determined, though speculation focuses on tuberculosis, stomach cancer, or a combination of the two.^[59] The headaches which affected Pascal are generally attributed to his brain lesion.^[60]

Legacy

One of the Universities of Clermont-Ferrand, France—Université Blaise Pascal—is named after him. Établissement scolaire français Blaise-Pascal in Lubumbashi, Democratic Republic of the Congo is named after Pascal.

The 1969 Eric Rohmer film My Night at Maud's is based on the work of Pascal. Roberto Rossellini directed a filmed biopic, Blaise Pascal, which originally aired on Italian television in 1971.^[61] Pascal was a subject of the first edition of the 1984 BBC Two documentary, Sea of Faith, presented by Don Cupitt. The chameleon in the animated film Tangled is named for Pascal.

A programming language is named for Pascal. In 2014, Nvidia announced its new Pascal microarchitecture, which is named for Pascal. The first graphics cards featuring Pascal were released in 2016.

The 2017 game Nier: Automata has multiple characters named after famous philosophers; one of these is a sentient pacifistic machine named Pascal, who serves as a major supporting character. Pascal creates a village for machines to live peacefully with the androids they are at war with and acts as a parental figure for other machines trying to adapt to their newly-found individuality.

The otter in the Animal Crossing series is named for Pascal.^[62]

The minor planet 4500 Pascal is named in his honor.^[63]

Pope Paul VI, in encyclical Populorum progressio, issued in 1967, quotes Pascal's Pensées:

True humanism points the way toward God and acknowledges the task to which we are called, the task which offers us the real meaning of human life. Man is not the ultimate measure of man. Man becomes truly man only by passing beyond himself. In the words of Pascal: "Man infinitely surpasses man.^[64]

In 2023, Pope Francis released an apostolic letter, Sublimitas et miseria hominis, dedicated to Blaise Pascal, in commemoration of the fourth centenary of his birth.

Pascal influenced both French sociologist Pierre Bourdieu, who named his Pascalian Meditations (1997) after him,^[65] and French philosopher Louis Althusser.^[66]

Works

Essai pour les coniques [Essay on conics] (1639)
Experiences nouvelles touchant le vide [New experiments with the vacuum] (1647)
Récit de la grande expérience de l'équilibre des liqueurs [Account of the great experiment on equilibrium in liquids] (1648)
Traité du triangle arithmétique [Treatise on the arithmetical triangle] (written c. 1654;^[67] publ. 1665)
Lettres provinciales [The Provincial Letters] (1656–57)
De l'Esprit géométrique [On the Geometrical Spirit] (1657 or 1658)
Écrit sur la signature du formulaire (1661)
Pensées [Thoughts] (incomplete at death; publ. 1670)
Discours sur les passions de l'amour [Discourse on the Passion of Love] (forgery)
On the Conversion of the Sinner
Ecrits sur la grace [Writings on Grace]

Notes

/pæˈskæl/ pass-KAL, also UK: /-ˈskɑːl, ˈpæskəl, -skæl/ -⁠KAHL, PASS-kəl, -⁠kal, US: /pɑːˈskɑːl/ pahs-KAHL;^[1]^[2]^[3]^[4]^[5] French: [blɛz paskal]
1 ligne = 2.256 mm, and 1 toise = 1.949 m. Mercury density is 13.534 g/cm3. So by Pascal's numbers, the density of air is about 1.1 kg/m³.

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