Blaise Pascal (June 19, 1623 - August 19, 1662) was a French mathematician, physicist and religious philosopher. His contributions to the natural sciences include the construction of mechanical calculators, considerations on probability theory, studies of fluids, and clarification of concepts such as pressure and vacuum. Following a profound religious experience in 1654, Pascal abandoned mathematics and physics for philosophy and theology.
Born in Clermont-Ferrand, Puy-de-Dôme, France, Blaise Pascal lost his mother at the age of three. His mathematician father, Étienne Pascal (1588 - 1651), brought him up. Blaise Pascal was the brother of Jacqueline Pascal (1625 - 1661).
Computer historians recognize his contribution to their field as his construction at the age of 18 of a mechanical calculator capable of addition and subtraction (the Zwinger museum, in Dresden, Germany exhibits one of his original mechanical calculators). He also produced a treatise on conic sections as a young man. In 1654, prompted by a friend interested in gambling problems, he corresponded with Fermat and laid out a simple account of probabilities.
He later formulated Pascal's wager, an argument for the belief in God based on probabilities. Pascal's triangle, a way to present binomial coefficients, also bears his name, though mathematicians knew binomial coefficients long before his time.
His notable contributions to the fields of the study of fluids (hydrodynamics and hydrostatics) centered around the principles of hydraulic fluids. His inventions include the hydraulic press (using hydraulic pressure to multiply force) and the syringe. He clarified concepts such as pressure (the unit of which bears his name) and vacuum.
In 1650, suffering from frail health, Pascal retired from mathematics. However, in 1653, his health recovered and he wrote Traité du triangle arithmétique in which he described the "arithmetical triangle" that bears his name.
Following an accident at the Neuilly bridge where the horses plunged over the parapet but the carriage miraculously survived in 1654, Pascal abandoned mathematics and physics for philosophy and theology. In 1660, King Louis XIV of France ordered the shredding and burning of Pascal's The Provincial Letters, a defense of the Jansenist Antoine Arnauld.
Pascal never completed his most influential work, the Pensées, but a version of his notes for that book appeared in print in 1670, eight years after his death, and it soon became a classic of devotional literature.
Pascal also attained fame for his attack on casuistry, a popular ethical method used by Catholic thinkers in the early modern period, (especially the Jesuits). Pascal denounced casuistry as the mere use of complex reasoning to justify moral laxity. His writings on this subject appeared as the Lettres provinciales, or "Provincial Letters."