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Blaise Pascal (19June 162319August 1662) was a French
mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...
,
physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...
, inventor,
philosopher Philosophy ('love of wisdom' in Ancient Greek) is a systematic study of general and fundamental questions concerning topics like existence, reason, knowledge, Value (ethics and social sciences), value, mind, and language. It is a rational an ...
, and
Catholic The Catholic Church (), also known as the Roman Catholic Church, is the List of Christian denominations by number of members, largest Christian church, with 1.27 to 1.41 billion baptized Catholics Catholic Church by country, worldwid ...
writer. Pascal was a
child prodigy A child prodigy is, technically, a child under the age of 10 who produces meaningful work in some domain at the level of an adult expert. The term is also applied more broadly to describe young people who are extraordinarily talented in some f ...
who was educated by his father, a tax collector in
Rouen Rouen (, ; or ) is a city on the River Seine, in northwestern France. It is in the prefecture of Regions of France, region of Normandy (administrative region), Normandy and the Departments of France, department of Seine-Maritime. Formerly one ...
. His earliest mathematical work was on
projective geometry In mathematics, projective geometry is the study of geometric properties that are invariant with respect to projective transformations. This means that, compared to elementary Euclidean geometry, projective geometry has a different setting (''p ...
; he wrote a significant treatise on the subject of
conic section A conic section, conic or a quadratic curve is a curve obtained from a cone's surface intersecting a plane. The three types of conic section are the hyperbola, the parabola, and the ellipse; the circle is a special case of the ellipse, tho ...
s at the age of 16. He later corresponded with
Pierre de Fermat Pierre de Fermat (; ; 17 August 1601 – 12 January 1665) was a French mathematician who is given credit for early developments that led to infinitesimal calculus, including his technique of adequality. In particular, he is recognized for his d ...
on
probability theory Probability theory or probability calculus is the branch of mathematics concerned with probability. Although there are several different probability interpretations, probability theory treats the concept in a rigorous mathematical manner by expre ...
, strongly influencing the development of modern economics and
social science Social science (often rendered in the plural as the social sciences) is one of the branches of science, devoted to the study of societies and the relationships among members within those societies. The term was formerly used to refer to the ...
. 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. Like his contemporary
René Descartes René Descartes ( , ; ; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and Modern science, science. Mathematics was paramou ...
, Pascal was also a pioneer in the natural and applied sciences. Pascal wrote in defense of the
scientific method The scientific method is an Empirical evidence, empirical method for acquiring knowledge that has been referred to while doing science since at least the 17th century. Historically, it was developed through the centuries from the ancient and ...
and produced several controversial results. He made important contributions to the study of
fluid In physics, a fluid is a liquid, gas, or other material that may continuously motion, move and Deformation (physics), deform (''flow'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are M ...
s, and clarified the concepts of
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...
and
vacuum A vacuum (: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective (neuter ) meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressur ...
by generalising the work of
Evangelista Torricelli Evangelista Torricelli ( ; ; 15 October 160825 October 1647) was an Italian people, Italian physicist and mathematician, and a student of Benedetto Castelli. He is best known for his invention of the barometer, but is also known for his advances i ...
. The SI unit for pressure is named for Pascal. Following Torricelli and
Galileo Galilei Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 â€“ 8 January 1642), commonly referred to as Galileo Galilei ( , , ) or mononymously as Galileo, was an Italian astronomer, physicist and engineer, sometimes described as a poly ...
, in 1647 he rebutted the likes of
Aristotle Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...
and Descartes who insisted that nature abhors a vacuum. He is also credited as the inventor of modern
public transport Public transport (also known as public transit, mass transit, or simply transit) are forms of transport available to the general public. It typically uses a fixed schedule, route and charges a fixed fare. There is no rigid definition of whic ...
ation, having established the carrosses à cinq sols, the first modern public transport service, shortly before his death in 1662. In 1646, he and his sister Jacqueline identified with the religious movement within
Catholicism The Catholic Church (), also known as the Roman Catholic Church, is the List of Christian denominations by number of members, largest Christian church, with 1.27 to 1.41 billion baptized Catholics Catholic Church by country, worldwid ...
known by its detractors as Jansenism. 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 and the '' Pensées'', the former set in the conflict between Jansenists and
Jesuits The Society of Jesus (; abbreviation: S.J. or SJ), also known as the Jesuit Order or the Jesuits ( ; ), is a religious order (Catholic), religious order of clerics regular of pontifical right for men in the Catholic Church headquartered in Rom ...
. The latter contains Pascal's wager, known in the original as the ''Discourse on the Machine'', 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 In geometry, a cycloid is the curve traced by a point on a circle as it Rolling, rolls along a Line (geometry), straight line without slipping. A cycloid is a specific form of trochoid and is an example of a roulette (curve), roulette, a curve g ...
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 Clermont-Ferrand (, , ; or simply ; ) is a city and Communes of France, commune of France, in the Auvergne-Rhône-Alpes regions of France, region, with a population of 147,284 (2020). Its metropolitan area () had 504,157 inhabitants at the 2018 ...
, which is in France's Auvergne region, by the Massif Central. He lost his mother, Antoinette Begon, at the age of three. 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, 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. 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. 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 Euclid (; ; BC) was an ancient Greek mathematician active as a geometer and logician. Considered the "father of geometry", he is chiefly known for the '' Elements'' treatise, which established the foundations of geometry that largely domina ...
’s first thirty-two geometric propositions, and was thus given a copy of Euclid's ''Elements''.


''Essay on Conics''

Particularly of interest to Pascal was a work of Desargues on
conic section A conic section, conic or a quadratic curve is a curve obtained from a cone's surface intersecting a plane. The three types of conic section are the hyperbola, the parabola, and the ellipse; the circle is a special case of the ellipse, tho ...
s. Following Desargues' thinking, the 16-year-old Pascal produced, as a means of proof, a short treatise on what was called the ''Mystic
Hexagram , can be seen as a compound polygon, compound composed of an upwards (blue here) and downwards (pink) facing equilateral triangle, with their intersection as a regular hexagon (in green). A hexagram (Greek language, Greek) or sexagram (Latin l ...
'', ''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 René Descartes ( , ; ; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and Modern science, science. Mathematics was paramou ...
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: "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."


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. The money was invested in a
government bond A government bond or sovereign bond is a form of Bond (finance), bond issued by a government to support government spending, public spending. It generally includes a commitment to pay periodic interest, called Coupon (finance), coupon payments' ...
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 Armand Jean du Plessis, 1st Duke of Richelieu (9 September 1585 – 4 December 1642), commonly known as Cardinal Richelieu, was a Catholic Church in France, French Catholic prelate and statesman who had an outsized influence in civil and religi ...
, desperate for money to carry on the
Thirty Years' War The Thirty Years' War, fought primarily in Central Europe between 1618 and 1648, was one of the most destructive conflicts in History of Europe, European history. An estimated 4.5 to 8 million soldiers and civilians died from battle, famine ...
, defaulted on the government's bonds. Suddenly Étienne Pascal's worth had dropped from nearly 66,000 livres to less than 7,300. 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 Rouen (, ; or ) is a city on the River Seine, in northwestern France. It is in the prefecture of Regions of France, region of Normandy (administrative region), Normandy and the Departments of France, department of Seine-Maritime. Formerly one ...
—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 The Musée des Arts et Métiers (; English: Museum of Arts and Crafts) is an industrial design museum in Paris that houses the collection of the Conservatoire national des arts et métiers, which was founded in 1794 as a repository for the preser ...
in Paris and one more by the Zwinger museum in
Dresden Dresden (; ; Upper Saxon German, Upper Saxon: ''Dräsdn''; , ) is the capital city of the States of Germany, German state of Saxony and its second most populous city after Leipzig. It is the List of cities in Germany by population, 12th most p ...
, Germany, exhibit two of his original mechanical calculators. 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 Computer engineering (CE, CoE, or CpE) is a branch of engineering specialized in developing computer hardware and software. It integrates several fields of electrical engineering, electronics engineering and computer science. Computer engi ...
, 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 A status symbol is a visible, external symbol of one's social position, an indicator of Wealth, economic or social status. Many luxury goods are often considered status symbols. ''Status symbol'' is also a Sociology, sociological term – as part ...
, for the very rich both in France and elsewhere in Europe. 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. He built 20 finished machines over the following 10 years.


Mathematics


Probability

In 1654, prompted by his friend the Chevalier de Méré, Pascal corresponded with
Pierre de Fermat Pierre de Fermat (; ; 17 August 1601 – 12 January 1665) was a French mathematician who is given credit for early developments that led to infinitesimal calculus, including his technique of adequality. In particular, he is recognized for his d ...
on the subject of gambling problems, and from that collaboration was born the mathematical theory of
probability Probability is a branch of mathematics and statistics concerning events and numerical descriptions of how likely they are to occur. The probability of an event is a number between 0 and 1; the larger the probability, the more likely an e ...
. 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 In probability theory, the expected value (also called expectation, expectancy, expectation operator, mathematical expectation, mean, expectation value, or first Moment (mathematics), moment) is a generalization of the weighted average. Informa ...
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." 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 Christiaan Huygens, Halen, Lord of Zeelhem, ( , ; ; also spelled Huyghens; ; 14 April 1629 – 8 July 1695) was a Dutch mathematician, physicist, engineer, astronomer, and inventor who is regarded as a key figure in the Scientific Revolution ...
, 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 Pierre-Simon, Marquis de Laplace (; ; 23 March 1749 â€“ 5 March 1827) was a French polymath, a scholar whose work has been instrumental in the fields of physics, astronomy, mathematics, engineering, statistics, and philosophy. He summariz ...
. The work done by Fermat and Pascal into the calculus of probabilities laid important groundwork for Leibniz's formulation of the
calculus Calculus is the mathematics, mathematical study of continuous change, in the same way that geometry is the study of shape, and algebra is the study of generalizations of arithmetic operations. Originally called infinitesimal calculus or "the ...
.


''Treatise on the Arithmetical Triangle''

Pascal's ''Traité du triangle arithmétique'', written in 1654 but published posthumously in 1665, described a convenient tabular presentation for
binomial coefficient In mathematics, the binomial coefficients are the positive integers that occur as coefficients in the binomial theorem. Commonly, a binomial coefficient is indexed by a pair of integers and is written \tbinom. It is the coefficient of the t ...
s which he called the arithmetical triangle, but is now called
Pascal's triangle In mathematics, Pascal's triangle is an infinite triangular array of the binomial coefficients which play a crucial role in probability theory, combinatorics, and algebra. In much of the Western world, it is named after the French mathematician Bla ...
. The triangle can also be represented: He defined the numbers in the triangle by
recursion Recursion occurs when the definition of a concept or process depends on a simpler or previous version of itself. Recursion is used in a variety of disciplines ranging from linguistics to logic. The most common application of recursion is in m ...
: 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 ''t''00 = 1. Pascal concluded with the proof, :t_ = \frac. In the same treatise, Pascal gave an explicit statement of the principle of
mathematical induction Mathematical induction is a method for mathematical proof, proving that a statement P(n) is true for every natural number n, that is, that the infinitely many cases P(0), P(1), P(2), P(3), \dots  all hold. This is done by first proving a ...
. 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''. 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 and, to publicize the results, proposed a contest. 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
doubloon The doubloon (from Spanish language, Spanish ''doblón'', or "double", i.e. ''double escudo'') was a two-''Spanish escudo, escudo'' gold coin worth approximately four Spanish dollars or 32 ''Spanish real, reales'', and weighing 6.766 grams (0.218 ...
s. Pascal, Gilles de Roberval and Pierre de Carcavi were the judges, and neither of the two submissions (by
John Wallis John Wallis (; ; ) was an English clergyman and mathematician, who is given partial credit for the development of infinitesimal calculus. Between 1643 and 1689 Wallis served as chief cryptographer for Parliament and, later, the royal court. ...
and Antoine de Lalouvère) were judged to be adequate. While the contest was ongoing,
Christopher Wren Sir Christopher Wren FRS (; – ) was an English architect, astronomer, mathematician and physicist who was one of the most highly acclaimed architects in the history of England. Known for his work in the English Baroque style, he was ac ...
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 Pascal's law (also Pascal's principle or the principle of transmission of fluid-pressure) is a principle in fluid mechanics that states that a pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid su ...
(an important principle of hydrostatics). He introduced a primitive form of
roulette Roulette (named after the French language, French word meaning "little wheel") is a casino game which was likely developed from the Italy, Italian game Biribi. In the game, a player may choose to place a bet on a single number, various grouping ...
and the roulette wheel in his search for a
perpetual motion Perpetual motion is the motion of bodies that continues forever in an unperturbed system. A perpetual motion machine is a hypothetical machine that can do work indefinitely without an external energy source. This kind of machine is impossible ...
machine.


Fluid dynamics

His work in the fields of
hydrodynamics In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in ...
and
hydrostatics Hydrostatics is the branch of fluid mechanics that studies fluids at hydrostatic equilibrium and "the pressure in a fluid or exerted by a fluid on an immersed body". The word "hydrostatics" is sometimes used to refer specifically to water and ...
centered on the principles of hydraulic fluids. His inventions include the hydraulic press (using hydraulic pressure to multiply force) and the
syringe A syringe is a simple reciprocating pump consisting of a plunger (though in modern syringes, it is actually a piston) that fits tightly within a cylindrical tube called a barrel. The plunger can be linearly pulled and pushed along the inside ...
. 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 Evangelista Torricelli ( ; ; 15 October 160825 October 1647) was an Italian people, Italian physicist and mathematician, and a student of Benedetto Castelli. He is best known for his invention of the barometer, but is also known for his advances i ...
's experimentation with
barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis ...
s. 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 A vacuum (: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective (neuter ) meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressur ...
(" Nature abhors a vacuum)." This was based on the Aristotelian notion that everything in motion was a substance, moved by another substance. 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 Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The Standard atmosphere (unit), standard atmosphere (symbol: atm) is a unit of pressure defined as , whi ...
. 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, tall, but his health was poor so could not climb it. 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: 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. Note: Pascal used ''pouce'' and ''ligne'' for "inch" and "line", and '' toise'' for "fathom". In a reply to Étienne Noël, who believed in the plenum, Pascal wrote, echoing contemporary notions of science and
falsifiability Falsifiability (or refutability) is a deductive standard of evaluation of scientific theories and hypotheses, introduced by the Philosophy of science, philosopher of science Karl Popper in his book ''The Logic of Scientific Discovery'' (1934). ...
: "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." Blaise Pascal Chairs are given to outstanding international scientists to conduct their research in the Ile de France region.


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..." 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 A postulant (from , "to ask") was originally one who makes a request or demand; hence, a candidate. The use of the term is now generally restricted to those asking for admission into a Christian monastery or a religious order for the period precedi ...
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. 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..." 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." 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.Richard H. Popkin, Paul Edwards (ed.), ''Encyclopedia of Philosophy'', 1967 edition, s.v. "Pascal, Blaise.", vol. 6, p. 52–55, New York: Macmillan


''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.Pascal, Blaise. ''Oeuvres complètes''. (Paris: Seuil, 1960), p. 618 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. 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
polemic Polemic ( , ) is contentious rhetoric intended to support a specific position by forthright claims and to undermine the opposing position. The practice of such argumentation is called polemics, which are seen in arguments on controversial to ...
ists.


The ''Provincial Letters''

Beginning in 1656–57, Pascal published his memorable attack on
casuistry Casuistry ( ) is a process of reasoning that seeks to resolve moral problems by extracting or extending abstract rules from a particular case, and reapplying those rules to new instances. This method occurs in applied ethics and jurisprudence. ...
, a popular
ethical Ethics is the philosophical study of moral phenomena. Also called moral philosophy, it investigates normative questions about what people ought to do or which behavior is morally right. Its main branches include normative ethics, applied e ...
method used by
Catholic The Catholic Church (), also known as the Roman Catholic Church, is the List of Christian denominations by number of members, largest Christian church, with 1.27 to 1.41 billion baptized Catholics Catholic Church by country, worldwid ...
thinkers in the early modern period (especially the
Jesuits The Society of Jesus (; abbreviation: S.J. or SJ), also known as the Jesuit Order or the Jesuits ( ; ), is a religious order (Catholic), religious order of clerics regular of pontifical right for men in the Catholic Church headquartered in Rom ...
, and in particular Antonio Escobar). Pascal denounced casuistry as the mere use of complex reasoning to justify moral laxity and all sorts of
sin In religious context, sin is a transgression against divine law or a law of the deities. Each culture has its own interpretation of what it means to commit a sin. While sins are generally considered actions, any thought, word, or act considered ...
s. The 18-letter series was published between 1656 and 1657 under the pseudonym Louis de Montalte and incensed
Louis XIV LouisXIV (Louis-Dieudonné; 5 September 16381 September 1715), also known as Louis the Great () or the Sun King (), was King of France from 1643 until his death in 1715. His verified reign of 72 years and 110 days is the List of longest-reign ...
. 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 A papal bull is a type of public decree, letters patent, or charter issued by the pope of the Catholic Church. It is named after the leaden Seal (emblem), seal (''bulla (seal), bulla'') traditionally appended to authenticate it. History Papal ...
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 François-Marie Arouet (; 21 November 169430 May 1778), known by his ''Pen name, nom de plume'' Voltaire (, ; ), was a French Age of Enlightenment, Enlightenment writer, philosopher (''philosophe''), satirist, and historian. Famous for his wit ...
and
Jean-Jacques Rousseau Jean-Jacques Rousseau (, ; ; 28 June 1712 – 2 July 1778) was a Republic of Geneva, Genevan philosopher (''philosophes, philosophe''), writer, and composer. His political philosophy influenced the progress of the Age of Enlightenment through ...
. 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."


Philosophy

Pascal is arguably best known as a philosopher, considered by some the second greatest French mind behind
René Descartes René Descartes ( , ; ; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and Modern science, science. Mathematics was paramou ...
. He was a dualist following Descartes. However, he is also remembered for his opposition to both the
rationalism In philosophy, rationalism is the Epistemology, epistemological view that "regards reason as the chief source and test of knowledge" or "the position that reason has precedence over other ways of acquiring knowledge", often in contrast to ot ...
of the likes of Descartes and simultaneous opposition to the main countervailing epistemology,
empiricism In philosophy, empiricism is an epistemological view which holds that true knowledge or justification comes only or primarily from sensory experience and empirical evidence. It is one of several competing views within epistemology, along ...
, preferring
fideism Fideism ( ) is a standpoint or an epistemological theory which maintains that faith is independent of reason, or that reason and faith are hostile to each other and faith is superior at arriving at particular truths (see natural theology). The ...
. 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". He opposed the rationalism of people like Descartes as applied to the existence of a God, preferring faith as "reason can decide nothing here". 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". 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".


Philosophy of mathematics

Pascal's major contribution to the
philosophy of mathematics Philosophy of mathematics is the branch of philosophy that deals with the nature of mathematics and its relationship to other areas of philosophy, particularly epistemology and metaphysics. Central questions posed include whether or not mathem ...
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 A definition is a statement of the meaning of a term (a word, phrase, or other set of symbols). Definitions can be classified into two large categories: intensional definitions (which try to give the sense of a term), and extensional definitio ...
. 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 Essentialism is the view that objects have a set of attributes that are necessary to their Identity (philosophy), identity. In early Western thought, Platonic idealism held that all things have such an "essence"—an Theory of forms, "idea" or "f ...
. 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 In mathematics and logic, an axiomatic system is a set of formal statements (i.e. axioms) used to logically derive other statements such as lemmas or theorems. A proof within an axiom system is a sequence of deductive steps that establis ...
, specifically the question of how people come to be convinced of the
axioms An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...
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

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 French ( or ) is a Romance languages, Romance language of the Indo-European languages, Indo-European family. Like all other Romance languages, it descended from the Vulgar Latin of the Roman Empire. French evolved from Northern Old Gallo-R ...
.Sainte-Beuve
''Seventeenth Century''
p. 174 (2009 reprint).
Will Durant hailed the Pensées as "the most eloquent book in French prose".'' The Story of Civilization: Volume 8, "The Age of Louis XIV"'' by Will & Ariel Durant, chapter II, Subsection 4.4, p. 66 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 Stoicism is a school of Hellenistic philosophy that flourished in ancient Greece and Rome. The Stoics believed that the universe operated according to reason, ''i.e.'' by a God which is immersed in nature itself. Of all the schools of ancient ...
, 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."Muir, Jane
''Of Men and Numbers''
. (New York: Dover Publications, Inc, 1996). , p. 104.
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." 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 Public transport (also known as public transit, mass transit, or simply transit) are forms of transport available to the general public. It typically uses a fixed schedule, route and charges a fixed fare. There is no rigid definition of whic ...
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. The lines were not commercially successful, and the last one closed by 1675. Nonetheless, he has been described as the inventor of public transportation.


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. An
autopsy An autopsy (also referred to as post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of deat ...
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 Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...
,
stomach cancer Stomach cancer, also known as gastric cancer, is a malignant tumor of the stomach. It is a cancer that develops in the Gastric mucosa, lining of the stomach. Most cases of stomach cancers are gastric carcinomas, which can be divided into a numb ...
, or a combination of the two.Muir, Jane
''Of Men and Numbers''
. (New York: Dover Publications, Inc, 1996). , p. 103.
The headaches which affected Pascal are generally attributed to his brain
lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by injury or diseases. The term ''Lesion'' is derived from the Latin meaning "injury". Lesions may occur in both plants and animals. Types There is no de ...
.


Legacy

One of the Universities of
Clermont-Ferrand Clermont-Ferrand (, , ; or simply ; ) is a city and Communes of France, commune of France, in the Auvergne-Rhône-Alpes regions of France, region, with a population of 147,284 (2020). Its metropolitan area () had 504,157 inhabitants at the 2018 ...
, France Université Blaise Pascalis named after him. Établissement scolaire français Blaise-Pascal in
Lubumbashi Lubumbashi ( , ; former ; former ) is the second-largest Cities of the Democratic Republic of the Congo, city in the Democratic Republic of the Congo, located in the country's southeasternmost part, along the border with Zambia. The capital ...
, 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. Pascal was a subject of the first edition of the 1984
BBC Two BBC Two is a British free-to-air Public service broadcasting in the United Kingdom, public broadcast television channel owned and operated by the BBC. It is the corporation's second flagship channel, and it covers a wide range of subject matte ...
documentary, '' Sea of Faith'', presented by Don Cupitt. The chameleon in the animated film '' Tangled'' is named for Pascal. A
programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...
is named for Pascal. In 2014,
Nvidia Nvidia Corporation ( ) is an American multinational corporation and technology company headquartered in Santa Clara, California, and incorporated in Delaware. Founded in 1993 by Jensen Huang (president and CEO), Chris Malachowsky, and Curti ...
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. The
minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
4500 Pascal is named in his honor.
Pope Paul VI Pope Paul VI (born Giovanni Battista Enrico Antonio Maria Montini; 26 September 18976 August 1978) was head of the Catholic Church and sovereign of the Vatican City State from 21 June 1963 until his death on 6 August 1978. Succeeding John XXII ...
, in
encyclical An encyclical was originally a circular letter sent to all the churches of a particular area in the ancient Roman Church. At that time, the word could be used for a letter sent out by any bishop. The word comes from the Late Latin (originally fr ...
'' Populorum progressio'', issued in 1967, quotes Pascal's ''Pensées'': In 2023,
Pope Francis Pope Francis (born Jorge Mario Bergoglio; 17 December 1936 – 21 April 2025) was head of the Catholic Church and sovereign of the Vatican City State from 13 March 2013 until Death and funeral of Pope Francis, his death in 2025. He was the fi ...
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 Pierre Bourdieu (, ; ; ; 1 August 1930 – 23 January 2002) was a French sociologist and public intellectual. Bourdieu's contributions to the sociology of education, the theory of sociology, and sociology of aesthetics have achieved wide influ ...
, who named his ''Pascalian Meditations'' (1997) after him, and French philosopher
Louis Althusser Louis Pierre Althusser (, ; ; 16 October 1918 – 22 October 1990) was a French Marxist philosopher who studied at the École Normale Supérieure in Paris, where he eventually became Professor of Philosophy. Althusser was a long-time member an ...
.


Works

* ''Essai pour les coniques'' ssay on conics(1639) * ''Experiences nouvelles touchant le vide'' ew experiments with the vacuum(1647) * ''Récit de la grande expérience de l'équilibre des liqueurs'' ccount of the great experiment on equilibrium in liquids(1648) * ''Traité du triangle arithmétique'' reatise on the arithmetical triangle(written ; publ. 1665) * he Provincial Letters(1656–57) * ''De l'Esprit géométrique'' n the Geometrical Spirit(1657 or 1658) * ''Écrit sur la signature du formulaire'' (1661) * '' Pensées'' houghts(incomplete at death; publ. 1670) * '' Discours sur les passions de l'amour'' iscourse on the Passion of Love(forgery) * '' On the Conversion of the Sinner'' * ''Ecrits sur la grace'' ritings on Grace


See also

*
Expected value In probability theory, the expected value (also called expectation, expectancy, expectation operator, mathematical expectation, mean, expectation value, or first Moment (mathematics), moment) is a generalization of the weighted average. Informa ...
* Gambler's ruin * List of pioneers in computer science * List of works by Eugène Guillaume * Pascal's barrel * Pascal distribution * Pascal's mugging * Pascal's pyramid * Pascal's simplex * Problem of points *
Scientific Revolution The Scientific Revolution was a series of events that marked the emergence of History of science, modern science during the early modern period, when developments in History of mathematics#Mathematics during the Scientific Revolution, mathemati ...


Notes


References


Further reading

* Adamson, Donald. ''Blaise Pascal: Mathematician, Physicist, and Thinker about God'' (1995) * Adamson, Donald
"Pascal's Views on Mathematics and the Divine,"
''Mathematics and the Divine: A Historical Study'' (eds. T. Koetsier and L. Bergmans. Amsterdam: Elsevier 2005), pp. 407–21. * Broome, J.H. ''Pascal''. London: E. Arnold, 1965. * Compagnon, Antoine. ''A Summer with Pascal''. Cambridge, Massachusetts: Belknap Press, 2024. * Campe, Rüdiger, "Numbers and Calculation in Context: The Game of Decision - Pascal" in The ''Game of Probability. Literature and Calculation from Pascal and Kleist'', Stanford University Press, 2012 *Davidson, Hugh M. ''Blaise Pascal''. Boston: Twayne Publishers, 1983. * * Farrell, John. "Pascal and Power". Chapter seven of ''Paranoia and Modernity: Cervantes to Rousseau'' (Cornell UP, 2006). * Goldmann, Lucien, ''The hidden God; a study of tragic vision in the Pensees of Pascal and the tragedies of Racine'' (original ed. 1955, Trans. Philip Thody. London: Routledge, 1964). * Groothuis, Douglas. ''On Pascal''. (Belmont: Wadsworth, 2002). * Jordan, Jeff. ''Pascal's Wager: Pragmatic Arguments and Belief in God''. Oxford: Clarendon Press, 2006. * Landkildehus, Søren. "Kierkegaard and Pascal as kindred spirits in the Fight against Christendom" in ''Kierkegaard and the Renaissance and Modern Traditions'' (ed. Jon Stewart. Farnham: Ashgate Publishing, 2009). * Mackie, John Leslie. ''The Miracle of Theism: Arguments for and against the Existence of God''. (Oxford: Oxford University Press, 1982). * Stafford Harry Northcote, Viscount Saint Cyres, ''Pascal'' (London: Smith, Elder & Company, 1909; New York: E. P. Dutton) * Pugh, Anthony R. ''The Composition of Pascal's Apologia'', (University of Toronto Press, 1984). * * * * Tobin, Paul. "The Rejection of Pascal's Wager: A Skeptic's Guide to the Bible and the Historical Jesus". authorsonline.co.uk, 2009.


External links


Oeuvres complètes, volume 2
(1858) Paris: Libraire de L Hachette et Cie, link from
HathiTrust HathiTrust Digital Library is a large-scale collaborative repository of digital content from research libraries. Its holdings include content digitized via Google Books and the Internet Archive digitization initiatives, as well as content digit ...
. * * *
The Correspondence of Blaise Pascal
i
EMLO
* * * * ''Pensées de Blaise Pascal''. Renouard, Paris 1812 (2 vols.) ()
Discussion of the Pascaline, its history, mechanism, surviving examples, and modern replicas at http://things-that-count.net


in orig. French/Latin and modern English, trans. Elizabeth T. Knuth.

(in French) *
BBC Radio 4. In Our Time: Pascal.


* ttp://www.intratext.com/Catalogo/Autori/Aut852.htm Blaise Pascal's works text, concordances and frequency lists * * Etext of Pascal's
Pensées
' (English, in various formats) * Etext of Pascal's

' (English) * Etext of a number of Pascal'
minor works
(English translation) including, ''De l'Esprit géométrique'' and ''De l'Art de persuader''. * {{DEFAULTSORT:Pascal, Blaise 1623 births 1662 deaths Writers from Clermont-Ferrand French Roman Catholic writers 17th-century French writers 17th-century French male writers 17th-century French mathematicians 17th-century French philosophers Aphorists Christian apologists Christian humanists Roman Catholic mystics Critics of atheism Converts to Roman Catholicism Dualists French fluid dynamicists French mathematicians French physicists 17th-century French theologians 17th-century Christian mystics People with hypochondriasis Jansenists French probability theorists Catholic philosophers 17th-century Roman Catholics Burials at Saint-Étienne-du-Mont Cartesianism Scientists from Clermont-Ferrand