He was born in Clermont-Ferrand, France, but lived mostly in Paris. He invented a calculating machine (1647), and later the barometer, the hydraulic press, and the syringe.

As a scientist he wrote treatises on the equilibrium of liquids and gases. The principle that liquid in a vessel carries pressures in all directions is called Pascal's Law.

A mystical experience in 1654 led him to join his sister, who was a member of the Jansenist convent at Port-Royal, where he defended Jansenism against the Jesuits in 'Lettres provinciales'. Fragments jotted down for a case book of Christian truth were discovered after his death and published as the Pensées. (Jansenism was a religious movement in opposition to the monarchial absolutism of Louis XIV and against the excesses of the Catholic Counter-Reformation).