View source for Blaise Pascal

{{dablink|For the programming language named after Blaise Pascal, see [[Pascal (programming language)]].}}
{{featured article}}
{{Infobox Philosopher 
| region           = Western Philosophy                                              
| era              = [[17th-century philosophy]] 
| color            = #B0C4DE 
| image_name       = Blaise_pascal.jpg
| image_caption    = Blaise Pascal
| name             = Blaise Pascal 
| birth_date       = {{birth date|1623|6|19|mf=y}}
| death_date       = {{death date and age|1662|8|19|1623|6|19|mf=y}}
| school_tradition = [[Continental Philosophy]], precursor to [[existentialism]]
| main_interests   = [[Theology]], [[Mathematics]]
| influences       = [[Michel de Montaigne]]
| notable_ideas    = [[Pascal's Wager]], [[Pascal's triangle]], [[Pascal's law]]
}}

''' Blaise Pascal''' ({{IPA-fr|blɛz paskal}}), (June 19, 1623, in [[Clermont-Ferrand]], [[France]] &ndash; August 19, 1662, in [[Paris]]) was a French [[mathematician]], [[physicist]], and [[religion|religious]] [[philosopher]]. He was a [[child prodigy]] who was educated by his father, a [[Civil service|civil servant]].  Pascal's earliest work was in the natural and applied [[science]]s where he made important contributions to the construction of mechanical [[calculator]]s, the study of [[fluid]]s, and clarified the concepts of [[pressure]] and [[vacuum]] by generalizing the work of [[Evangelista Torricelli]]. Pascal also wrote in defense of the [[scientific method]].

Pascal was a mathematician of the first order. He helped create two major new areas of research. He wrote a significant treatise on the subject of [[projective geometry]] at the age of sixteen, and later corresponded with [[Pierre de Fermat]] on [[probability theory]], strongly influencing the development of modern [[economics]] and [[social sciences|social science]]. Following [[Galileo]] and Torricelli, in 1646 he refuted [[Aristotle|Aristotle's]] followers who insisted that nature abhors a vacuum.  His results caused many disputes before being accepted.

In 1646, he and his sister Jacqueline identified with the religious movement within [[Catholicism]] known by its detractors as [[Jansenism]].<ref> {{cite web|url=http://www.newadvent.org/cathen/11511a.htm |title=Blaise Pascal |accessdate=2009-02-23 |work=Catholic Encyclopedia }}</ref>  His father died in 1651.  Following a [[mysticism|mystical]] experience in late 1654, he had his "second conversion", abandoned his scientific work, and devoted himself to 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]]. In this year, he also wrote an important treatise on the arithmetic of triangles.  Between 1658 and 1659 he wrote on the [[cycloid]] and its use in calculating the volume of solids.

Pascal had poor [[health]] throughout his life and  his death came just two months after his 39th birthday.<ref>Hald, Anders ''A History of Probability and Statistics and Its Applications before 1750'', (Wiley Publications, 1990) pp.44</ref>

==Early life and education==
Pascal lost his mother, Antoinette Begon, at the age of three.  His father, [[Étienne Pascal]] (1588–1651), who also had an interest in science and mathematics, was a local judge and member of the "[[Nobles of the Robe|Noblesse de Robe]]".  Pascal had two sisters, the younger [[Jacqueline Pascal|Jacqueline]] and the elder Gilberte.

In 1631, 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 an instrumental member of the family.  Étienne, who never remarried, decided that he alone would educate his children, for they all showed extraordinary intellectual ability, particularly his son Blaise.  The young Pascal showed an amazing aptitude for mathematics and science. At the age of eleven, he composed a short treatise on the sounds of vibrating bodies, and Étienne responded by forbidding his son to further pursue mathematics until the age of fifteen so as not to harm his study of [[Latin]] and [[Greek language|Greek]]. One day, however, Étienne found Blaise (now twelve) writing an independent proof that the sum of the [[angle]]s of a [[triangle]] is equal to two [[right angle]]s with a piece of coal on a wall. From then on, the boy was allowed to study [[Euclid]]; perhaps more importantly, he was allowed to sit in as a silent on-looker at the gatherings of some of the greatest mathematicians and scientists in Europe—such as [[Gilles de Roberval|Roberval]], [[Desargues]], [[Mydorge]], [[Pierre Gassendi|Gassendi]], and [[Descartes]]—in the monastic cell of [[Marin Mersenne|Père Mersenne]]. 

Particularly of interest to Pascal was a work of [[Desargues]] on [[conic section]]s. Following Desargues' thinking, the sixteen-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 [[Marin Mersenne|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 Descartes, when shown the manuscript, refused to believe that the composition was not by the elder Pascal. 
When assured by Mersenne that it was, indeed, the product of the son 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 sixteen-year-old child."<ref>''[[The Story of Civilization]]: Volume 8, "The Age of Louis XIV"'' by [[Will Durant|Will & Ariel Durant]]; chapter II, subsection 4.1 p.56)</ref>

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]].<ref>Connor, James A.,'' Pascal's Wager''(HarperCollins, NY,  2006) p.42</ref> 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 Richelieu, desperate for money to carry on the [[Thirty Year War]], defaulted on the government's bonds. Suddenly Étienne Pascal's worth had dropped from nearly 66,000 livres to less than 7,300.

[[Image:Arts et Metiers Pascaline dsc03869.jpg|left|thumb|An early [[Pascal's calculator|Pascaline]] on display at the [[Musée des Arts et Métiers]], Paris]]
Like so many others, Étienne was eventually forced to flee Paris because of his opposition to the fiscal policies of [[Cardinal Richelieu]], leaving his three children in the care of his neighbor 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.

In 1642, in an effort to ease his father's endless, exhausting calculations, and recalculations, of taxes owed and paid, Pascal, not yet nineteen,  constructed a mechanical calculator capable of addition and subtraction, called [[Pascal's calculator]] or the Pascaline.  The [[Musée des Arts et Métiers]] in [[Paris]] and the [[Zwinger|Zwinger museum]] in [[Dresden]], [[Germany]], exhibit two of his original mechanical calculators. Though these machines are early forerunners to [[computer engineering]], the calculator failed to be a great commercial success. Because it was extraordinarily expensive the [[Pascaline]] became little more than a toy, and [[status symbol]], for the very rich both in France and throughout Europe. However, Pascal continued to make improvements to his design through the next decade and built fifty machines in total.

==Contributions to mathematics==
[[Image:PascalTriangleAnimated2.gif|thumb|[[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 continued to influence mathematics throughout his life. His ''Traité du triangle arithmétique'' ("Treatise on the Arithmetical Triangle") of 1653 described a convenient tabular presentation for [[binomial coefficient]]s, now called [[Pascal's triangle]].  The triangle can also be represented:
{| class="wikitable" style="text-align:center"; border="1" 
|-
! style="width:20px;" | 
! style="width:20px;" | 0
! style="width:20px;" | 1
! style="width:20px;" | 2
! style="width:20px;" | 3
! style="width:20px;" | 4
! style="width:20px;" | 5
! style="width:20px;" | 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 defines the numbers in the triangle by [[recursion]]:  Call the number in the (m+1)st row and (n+1)st column t<sub>mn</sub>.  Then t<sub>mn</sub> = t<sub>m-1,n</sub> + t<sub>m,n-1</sub>, for m = 0, 1, 2... and n = 0, 1, 2...  The boundary conditions are t<sub>m, -1</sub> = 0, t<sub>-1, n</sub> for m = 1, 2, 3... and n = 1, 2, 3...  The generator t<sub>00</sub> = 1.  Pascal concludes with the proof,
:<math>t_{mn} = \frac{(m+n)(m+n-1)...(m+1)}{n(n-1)...1}.\ </math>

In 1654, prompted by a friend interested in gambling problems, he corresponded with [[Fermat]] on the subject, and from that collaboration was born the mathematical theory of [[probability|probabilities]]. The friend was the [[Chevalier de Méré]], and 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 [[division of the stakes|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. Pascal later (in the ''Pensées'') used a probabilistic argument, [[Pascal's Wager]], to justify belief in [[God]] and a virtuous life. The work done by Fermat and Pascal into the calculus of probabilities laid important groundwork for [[Leibniz|Leibniz']] formulation of the [[infinitesimal calculus]].<ref>{{cite web|url=http://www.math.rutgers.edu/courses/436/Honors02/leibniz.html |title=The Mathematical Leibniz |publisher=Math.rutgers.edu |date= |accessdate=2009-08-16}}</ref>

After a religious experience in 1654, Pascal mostly gave up work in mathematics. However, after a sleepless night in 1658, he anonymously offered a prize for the [[numerical integration|quadrature]] of a [[cycloid]]. Solutions were offered by [[John Wallis]], [[Christiaan Huygens]], [[Christopher Wren]], and others; Pascal, under the pseudonym Amos Dettonville, published his own solution. Controversy and heated argument followed after Pascal announced himself the winner. 

===Philosophy of mathematics===
Pascal's major contribution to the [[philosophy of mathematics]] came with his ''De l'Esprit géométrique'' ("On the Geometrical Spirit"), originally written as a preface to a geometry textbook for one of the famous "''[[Petites écoles de Port-Royal|Petites-Ecoles 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 only be grasped through intuition, and that this fact underscored the necessity for submission to [[God]] in searching out truths.

==Contributions to the physical sciences==
[[Image:Blaise Pascal 2.jpg|thumb|left|Portrait of Pascal]]

Pascal's work in the fields of the study of [[hydrodynamics]] and [[hydrostatics]] centered on the principles of [[hydraulic fluid]]s. His inventions include the [[hydraulic press]] (using hydraulic pressure to multiply force) and the [[syringe]]. By 1646, Pascal had learned of [[Evangelista Torricelli|Evangelista Torricelli's]] experimentation with [[barometer]]s. Having replicated an experiment which 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 contended that, rather than a [[vacuum]], some invisible matter was present. This was based on the Aristotelian notion that creation was a thing of substance, whether visible or invisible; and this substance was forever in motion. Furthermore, "Everything that is in motion must be moved by something," [[Aristotle]] declared.<ref>Aristotle,''Physics'',VII,1.</ref> Therefore, to the Aristotelian trained scientists of Pascal's time, a vacuum was an impossibility. How so? As proof it was pointed out:
* Light passed through the so-called "vacuum" in the glass tube.
* Aristotle wrote how everything moved, and must be moved by something.
* Therefore, since there had to be an invisible "something" to move the light through the glass tube, there was no vacuum in the tube. Not in the glass tube or anywhere else. Vacuums—the absence of any and everything—were simply an impossibility. 

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.

On September 19, 1648, after many months of Pascal's friendly but insistent prodding, Florin Périer, husband of Pascal's elder sister Gilberte, was finally to carry out the fact finding mission vital to Pascal's theory. The account, written by Périer, reads:

<blockquote>
"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-Ferrand|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 sixteen pounds of [[Mercury (element)|quicksilver]]...into a vessel...then took several glass tubes...each four feet long and [[Hermetic seal|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 3½ 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..."<ref>Périer to Pascal, September 1647,''Œuves completes de Pascal'', 2:682.</ref>

</blockquote>

Pascal replicated the experiment in [[Paris]] by carrying a barometer up to the top of the bell tower at the church of [[Saint-Jacques Tower|Saint-Jacques-de-la-Boucherie]], a height of about fifty meters. The mercury dropped two lines. These, and other lesser experiments carried out by Pascal, were hailed throughout Europe as establishing the principle and value of the barometer.

In the face of criticism that some invisible matter must exist in Pascal's empty space, Pascal, in his reply to [[Estienne Noel]],<!-- WAIT--WAIT! Before you remove the brackets, consider writing a new article! --> gave one of the seventeenth century's major statements on the scientific method: "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." His insistence on the existence of the vacuum also led to conflict with other prominent scientists, including [[Descartes]].

==Adult life, religion, philosophy, and literature==
{{bquote|For after all what is man in nature? A nothing in relation to infinity, all in relation to nothing, a central point between nothing and all and infinitely far from understanding either. The ends of things and their beginnings are impregnably concealed from him in an impenetrable secret. He is equally incapable of seeing the nothingness out of which he was drawn and the infinite in which he is engulfed.}}
:::::Blaise Pascal, ''Pensées'' #72

===Religious conversion===
Two basic influences led him to his conversion: sickness and [[Jansenism]].  From as early as his eighteenth year, Pascal suffered from a nervous ailment that left him hardly a day without pain.  In 1647, a paralytic attack so disabled him that he could not move without crutches.  His head ached, his bowels burned, his legs and feet were continually cold, and required wearisome aids to circulate the blood; he wore stockings steeped in brandy to warm his feet.  Partly to get better medical treatment, he moved to Paris with his sister Jacqueline.  His health improved, but his nervous system had been permanently damaged.  Henceforth, he was subject to deepening [[hypochondria]], which affected his character and his philosophy.  He became irritable, subject to fits of proud and imperious anger, and seldom smiled.<ref name="sickness">Sainte-Beuve, ''Port-Royal'', I, 89.</ref>
[[Image:Pascal Pajou Louvre RF2981.jpg|thumb|left|upright|Pascal studying the [[cycloid]], by [[Augustin Pajou]], 1785, [[Louvre]]]]

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 [[Hip fracture|broken hip]] could be a very serious condition, perhaps even fatal. Rouen was home to two of the finest doctors in France: Monsieur Doctor Deslandes and Monsieur Doctor 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..."<ref>Connor, James A.'' Pascal's Wager'' (HarperCollins, 2006)p.70</ref> But treatment and rehabilitation took three months, during which time La Bouteillerie and Deslandes had become household guests.

Both men were followers of [[Jean Guillebert]]<!-- WAIT--WAIT! Before you remove the brackets, consider writing a new article! -->, proponent of a splinter group from the main body of 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 upon his successful treatment of Étienne, borrowed works by Jansenist authors from them.  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 Jacqueline, of which Pascal acted as her 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 too needed her.<blockquote>

"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."<ref>Miel p.122</ref>
</blockquote>

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..."<ref>Jacqueline Pascal, ''"Memoir"'' p. 87</ref>
In early June of 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."<ref>Miel p.124</ref> 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.  He showed strong interest in one woman while in Auvergne. He referred to her as the "[[Sappho]] of the countryside."<ref name="sappho">Pascal, ''[[Pensées]]'', Havet ed. Introd., p. ''civ''.</ref>  During this time, Pascal wrote ''Discours sur les passions de l'amour'' ("Conversation about the Passions of Love") and apparently contemplated marriage &mdash; which he was later to describe as "the lowest of the conditions of life permitted to a Christian."<ref name="marriage">Mesnard, ''Pascal'', 57.</ref>
Jacqueline reproached him for his frivolity and prayed for his reform.<ref>''[[The Story of Civilization]]: Volume 8, "The Age of Louis XIV"'' by [[Will Durant|Will & Ariel Durant]], p.58)</ref> During visits to his sister at Port-Royal in 1654, he displayed contempt for affairs of the world but was not drawn to God.<ref name="ep52">''Encyclopedia of Philosophy'', 52.</ref>

===Brush with death===
In October 1654, Pascal is said to have been involved in an accident at the  [[Neuilly-sur-Seine]] bridge where the horses plunged over the parapet and the carriage nearly followed them. Fortunately, the reins broke and the coach hung halfway over the edge. Pascal and his friends emerged unscathed, but the sensitive philosopher, terrified by the nearness of death, fainted away and remained unconscious for some time. On 23 November 1654, between 10:30 and 12:30 at night, Pascal had an intense [[Vision (religion)|religious vision]] and immediately recorded the experience in 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.<ref name="oc618">''Oeuvres complètes'', 618.</ref> This piece is now known as the ''Memorial''. The story of the carriage accident as having led to the experience described in the ''Memorial'' is disputed by some scholars.<ref>MathPages, [http://www.mathpages.com/home/kmath558/kmath558.htm http://www.mathpages.com/.&nbsp;.&nbsp;.]</ref> 
His belief and religious commitment revitalized, Pascal visited the older of two convents at [[Port-Royal-des-Champs|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''

===The ''Provincial Letters''===
{{main|Lettres provinciales}}
{{French literature (small)}}

Beginning in 1656, Pascal published his memorable attack on [[casuistry]], a popular [[Ethics (philosophy)|ethical]] method used by [[Roman Catholic Church|Catholic]] thinkers in the early modern period (especially the [[Jesuits]], and in particular [[Antonio Escobar y Mendoza|Antonio Escobar]]). Pascal denounced casuistry as the mere use of complex reasoning to justify moral laxity and all sorts of [[sin]]s. His method of framing his arguments was clever: the ''Provincial Letters'' pretended to be the report of a Parisian to a friend in the provinces on the moral and theological issues then exciting the intellectual and religious circles in the capital. Pascal, combining the fervor of a convert with the wit and polish of a man of the world, reached a new level of style in French prose.  The 18-letter series was published between 1656 and 1657 under the pseudonym Louis de Montalte and incensed [[Louis XIV of France|Louis XIV]]. The king ordered that the book be shredded and burnt in 1660. In 1661, in the midsts 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 the Pope himself, provoking [[Alexander VII]] to condemn the letters.  But that didn't stop all of educated France from reading them.  Even Pope Alexander, while publicly opposing them, nonetheless was persuaded by Pascal's arguments.  He condemned "laxism" in the church and ordered a revision of casuistical texts just a few years later (1665–66).

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]].

Wide praise has been given to the ''Provincial Letters''.  [[Voltaire]] called the ''Letters'' "the best-written book that has yet appeared in France."<ref name="voltaireletters">Voltaire, ''Age of Louis XIV'' 424, 358.</ref>  And when [[Bossuet]] was asked what book he would rather have written had he not written his own, he answered, the ''Provincial Letters'' of Pascal.<ref name="bossuetletters">Voltaire, ''Age of Louis XIV'' 359.</ref>

===Miracle===
When Pascal was back in Paris just after overseeing the publication of the last ''Letter'', his religion was reinforced by the close association to an apparent miracle in the chapel of the Port-Royal nunnery.  His 10-year-old niece, Marguerite Périer, was suffering from a painful [[fistula]] lacrymalis that exuded noisome pus through her eyes and nose—an affliction the doctors pronounced hopeless.  Then, on March 24, 1657, a believer presented to Port-Royal what he and others claimed to be a thorn from the crown that had tortured Christ.  The nuns, in solemn ceremony and singing psalms, placed the thorn on their altar.  Each in turn kissed the relic, and one of them, seeing Marguerite among the worshipers, took the thorn and with it touched the girl's sore.  That evening, we are told, Marguerite expressed surprise that her eye no longer pained her; her mother was astonished to find no sign of the fistula; a physician, summoned, reported that the discharge and swelling had disappeared.  He, not the nuns, spread word of what he termed a miraculous cure.  Seven other physicians who had had previous knowledge of Marguerite's fistula signed a statement that in their judgment a miracle had taken place.  The diocesan officials investigated, came to the same conclusion, and authorized a [[Te Deum]] Mass in Port-Royal.  Crowds of believers came to see and kiss the thorn; all of Catholic Paris acclaimed a miracle.  Later, both pro and anti [[Jansenists]] used this well-documented miracle to their defense.  In 1728, [[Pope Benedict XIII]] referred to the case as proving that the age of miracles had not passed.

Pascal made himself an armorial emblem of an eye surrounded by a crown of thorns, with the inscription ''Scio cui credidi''—"I know whom I have believed."<ref name="thornmiracle">Sainte-Beuve, ''Port-Royal'', III, 173f.; Beard, Charles, ''Port-Royal'', I 84.</ref>  His beliefs renewed, he set his mind to write his final, unfinished testament, the ''Pensées''.

===The ''Pensées''===
{{wikisource|Pensées}}
{{main|Pensées}}
Pascal's most influential theological work, referred to posthumously as the ''Pensées'' ("Thoughts"), was not completed before his death.  It was to have been a sustained and coherent examination and defense of the [[Christianity|Christian faith]], with the original title ''Apologie de la religion Chrétienne'' ("Defense of the Christian Religion").  What was found upon sifting through his personal items after his death were numerous scraps of paper with isolated thoughts, grouped in a tentative, but telling, order.  The first version of the detached notes appeared in print as a book in 1670 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 [[skepticism]] 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. This strategy was deemed quite hazardous by [[Pierre Nicole]], [[Antoine Arnauld]] and other friends and scholars of Port-Royal, who were concerned that these fragmentary "thoughts" might lead to skepticism rather than to piety. Henceforth, they concealed the skeptical pieces and modified some of the rest, lest King or Church should take offense<ref name="peity">Pascal, ''[[Pensées]]'', Introduction, p. ''xxviii''; Mesnard, ''Pascal'', 137–138.</ref> for at that time the persecution of Port-Royal had ceased, and the editors were not interested in a renewal of controversy.  Not until the nineteenth century were the ''Pensées'' published in their full and authentic text.

Pascal's ''Pensées'' 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.<ref name="finest">Sainte-Beuve, ''Seventeenth Century'', 174.</ref>  [[Will Durant]], in his 11-volume, comprehensive ''[[The Story of Civilization]]'' series, hailed it as "the most eloquent book in French prose."<ref name="eloquent">''[[The Story of Civilization]]: Volume 8, "The Age of Louis XIV"'' by [[Will Durant|Will & Ariel Durant]], chapter II, Subsection 4.4 (pg. 66)</ref>  In ''Pensées'', Pascal surveys several philosophical paradoxes: infinity and nothing, faith and reason, soul and matter, death and life, meaning and vanity—seemingly arriving at no definitive conclusions besides humility, ignorance, and grace.  Rolling these into one he develops [[Pascal's Wager]].

===Last works and death===
[[Image:Epitaph Blaise Pascal Saint-Etienne.jpg|thumb|Pascal's epitaph in [[Saint-Étienne-du-Mont]], where he was buried]]

[[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 man to suffer. In 1659, Pascal, whose health had never been good, fell seriously ill. During his last years, he frequently tried to reject the ministrations of his doctors, saying, "Sickness is the natural state of Christians."<ref name="m104-">Muir, 104.</ref>

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]]. Pascal's last major achievement, returning to his mechanical genius, was inaugurating perhaps the first [[bus]] line, moving passengers within Paris in a carriage with many seats. 

In 1662, Pascal's illness became more violent. 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 August 18, 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]].<ref name="m104-" />

An [[autopsy]] performed after his death revealed grave problems with his stomach and other organs of his abdomen, along with [[brain damage|damage to his brain]]. Despite the autopsy, the cause of his continual poor health was never precisely determined, though speculation focuses on [[tuberculosis]], [[stomach cancer]], or a combination of the two.<ref name="m103">Muir, 103.</ref> The headaches which afflicted Pascal are generally attributed to his brain [[lesion]].

==Legacy==
In honor of his scientific contributions, the name '''Pascal''' has been given to the [[pascal (unit)|SI unit of pressure]], to a [[Pascal (programming language)|programming language]], and [[Pascal's law]] (an important principle of hydrostatics), and as mentioned above, Pascal's triangle and Pascal's wager still bear his name.

Pascal's development of probability theory was his most influential contribution to mathematics. Originally applied to [[gambling]], today it is extremely important in [[economics]], especially in [[actuarial science]]. 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."<ref>{{cite web|url=http://www.nature.com/embor/journal/v5/n1s/full/7400229.html |title=Pascal's legacy |publisher=Nature.com |date=2004-10-01 |accessdate=2009-08-16}}</ref> However, it should be noted that 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]].

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]]ists. The content of his literary work is best remembered for its strong opposition to the [[rationalism]] of [[René Descartes]] and simultaneous assertion that the main countervailing philosophy, [[empiricism]], was also insufficient for determining major truths.

==Works==
* ''Essai pour les coniques'' (1639)
* ''Experiences nouvelles touchant le vide'' (1647)
* ''Traité du triangle arithmétique'' (1653)
* ''[[Lettres provinciales]]'' (1656–57)
* ''De l'Esprit géométrique'' (1657 or 1658)
* ''Écrit sur la signature du formulaire'' (1661)
* ''[[Pensées]]'' (incomplete at death)

==Miscellany==
*In France, prestigious annual awards, [[Blaise Pascal Chair]]s are given to outstanding international scientists to conduct their research in the [[Île-de-France (région)|Ile de France]] region.<ref>{{cite web|url=http://www.chaires-blaise-pascal.org/uk/index.html |title=Chaires Blaise Pascal |publisher=Chaires Blaise Pascal |date= |accessdate=2009-08-16}}</ref>
*The [[University of Waterloo]], [[Ontario]], Canada, holds an annual math contest named in his honour. The Pascal Contest is open to any student from around the world, who is fifteen years or under and is in grade nine or lower.<ref>{{cite web|url=http://www.cemc.uwaterloo.ca/contests/pcf.html |title=CEMC - Pascal, Cayley and Fermat - Mathematics Contests - University of Waterloo |publisher=Cemc.uwaterloo.ca |date=2008-06-23 |accessdate=2009-08-16}}</ref>
*[[Roberto Rossellini]] directed a filmed biopic (entitled ''Blaise Pascal'') which originally aired on Italian television in 1971.
*Pascal was  a subject for the first edition of the 1984 BBC Two documentary, "The Sea of Faith", presented by [[Don Cupitt]] (see [[Sea of Faith: Television series]]).

==See also==
*[[Scientific Revolution]]

==Notes==
{{reflist|2}}
{{refbegin}}
* [[Donald Adamson|Adamson, Donald]]. ''Blaise Pascal: Mathematician, Physicist, and Thinker about God'' (1995) 
* Broome, JH. ''Pascal''. ISBN 0-7131-5021-1
* 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).
* [[Lucien Goldmann|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)
* Miel, Jan. ''Pascal and Theology''. Baltimore: John Hopkins University Press, 1969. 
* Muir, Jane. ''Of Men and Numbers''. New York: Dover Publications, Inc, 1996. ISBN 0-486-28973-7
* ''Encyclopedia of Philosophy'', 1967 edition, s.v. "Pascal, Blaise." <!-- vol. 6, pp 51–55, New York: Macmillan, Paul Edwards (ed.), Richard H. Popkin (article author) -->
* Pascal, Blaise. ''Oeuvres complètes''. Paris: Seuil, 1960.
* Pascal, Blaise. ''Oeuvres complètes''. Jean Mesnard, ed. 4 vols have appeared. Paris: Desclée-Brouwer, 1964-
{{refend}}

== External links ==
{{sisterlinks}}
*[http://www.users.csbsju.edu/~eknuth/pascal.html Pascal's Memorial] in orig. French/Latin and modern English, trans. Elizabeth T. Knuth.
* [http://www.nature.com/embor/journal/v5/n1s/full/7400229.html "Pascal's Legacy"], an article by John Ross on the influence of Pascal's probability theory.
* [http://www.biblioweb.org/-PASCAL-Blaise-.html Biography, Bibliography.] (in French)
* [http://www.eucliduniversity.org/euclid/en/school-bp.asp The Blaise Pascal School of Computing Sciences at Euclid University]
* {{gutenberg author|Pascal+Blaise|Blaise Pascal}}
* [http://www-personal.umich.edu/~jbourj/money5.htm Blaise Pascal featured on the 500 French Franc banknote in 1977.]
* [http://www.intratext.com/Catalogo/Autori/Aut852.htm Blaise Pascal's works]: text, concordances and frequency lists
* {{CathEncy|wstitle=Blaise Pascal}}
*[http://www.blaisepascal.org.uk/ Blaise Pascal College No.70]: A [[Rosicrucian]] ([[SRIA]]) college named after Pascal.
*[http://www.romancatholicism.org/ Primary texts and discussions relating to the theology and history of Pascal and Jansenism]
* [http://valure.wiki.ccsd.edu/Blaise+Pascal/ Middle School Mathematician Project] Short biography of Pascal by middle school students.
*Etext of Pascal's ''[http://www.ccel.org/ccel/pascal/pensees.html Pensées]'' (English, in various formats)
*Etext of Pascal's ''[http://oregonstate.edu/instruct/phl302/texts/pascal/letters-a.html Lettres Provinciales]'' (English)
*Etext of a number of Pascal's [http://www.bartleby.com/48/3/ minor works] (English translation) including, ''De l'Esprit géométrique'' and ''De l'Art de persuader''.
*{{MacTutor Biography|id=Pascal}}
{{Template group
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{{Catholicism|collapsed}} 
{{History of the Roman Catholic Church|collapsed}}
{{Roman Catholic Theology|collapsed}}
{{philosophy of religion}}
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|NAME= Pascal, Blaise
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|PLACE OF BIRTH= [[Clermont-Ferrand]], [[France]] 
|DATE OF DEATH= {{death date|1662|8|19|mf=y}} 
|PLACE OF DEATH= [[Paris]], [[France]] 
}}
[[Category:Blaise Pascal| ]]
[[Category:17th-century mathematicians]]
[[Category:Probability theorists]]
[[Category:French Roman Catholics]]
[[Category:French mathematicians]]
[[Category:French philosophers]]
[[Category:French physicists]]
[[Category:French spiritual writers]]
[[Category:French theologians]]
[[Category:17th-century French writers]]
[[Category:Computer pioneers]]
[[Category:Jansenists]]
[[Category:Christian apologists]]
[[Category:Christian philosophers]]
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[[Category:Roman Catholic philosophers]]
[[Category:Fluid dynamicists]]
[[Category:Religion and science]]
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