Blaise Pascal (blĕz päskäl´), 1623–62, French scientist and religious philosopher. Studying under the direction of his father, a civil servant, Pascal showed great precocity, especially in mathematics and science. Before he was 16 he wrote a paper on conic sections which won the respect of the mathematicians of Paris; at 19 he invented a calculating machine. Credited with founding the modern theory of probability, Pascal also discovered the properties of the cycloid and contributed to the advance of differential calculus. In physics his experiments increased knowledge of atmospheric pressure through barometric measurements and of the equilibrium of fluids (see Pascal's law). As a young man, Pascal came under the influence of Jansenism, and in 1651 his sister Jacqueline, who had also embraced Jansenist beliefs, entered the convent at Port-Royal, the center of the movement. As a result of the death of his father and of his own narrow escape from death, Pascal in 1654 experienced what he called a
and thereafter turned much of his attention to religion. When Antoine Arnauld, a noted Jansenist, was attacked by the Jesuits, Pascal championed him in his Lettre escrite à un provincial (1656). Those Provincial Letters, rendered into Latin, quickly circulated throughout Europe, and they still hold a leading place in the literature of polite irony. Pascal's religious writings were posthumously published as Pensées de M. Pascal sur la religion et sur quelques autres sujets (1670). For a modern edition see Thoughts: An Apology for Christianity (tr. 1955). In the Pensées, famous both as a religious and philosophical classic, Pascal states his belief in the inadequacy of reason to solve man's difficulties or to satisfy his hopes. He preached instead the final necessity of mystic faith for true understanding of the universe and its meaning to man.
See biographies by A. J. Krailsheimer (1980), H. H. Davidson (1983); studies by E. Cailliet (1944, repr. 1973), R. Hazelton (1974), S. E. Melzer (1986), and G. Hunter (2013).