Cornelis Jansen (1585-1638) was a Flemish theologian who founded the Roman Catholic reform movement known as Jansenism. He was born in Acquoi, near Leerdam, and educated at the universities of Utrecht, Leuven and Paris. During his school days he came in contact with the disciples of the Flemish Roman Catholic theologian Michael Baius (1513-1589), also known as Michel de Bay, and began a lifelong friendship with the French theologian Jean Duvergier de Hauranne, who later became abbot of Saint-Cyran and chaplain of the convent of Port-Royal-des-Champs near Paris.
Jansen defended the doctrine of absolute predestination. All individuals, he argued, are incapable of doing good without God's unsolicited grace; they are destined by God to be either saved or damned, and ultimately only a chosen few will receive salvation. In this respect, the doctrine closely resembles Calvinism, and Jansen and his followers were accused from the start of being Protestants in disguise. The Jansenists, however, always proclaimed their adherence to Roman Catholicism and announced that no salvation was possible outside the Roman Catholic church.
It entailed an austere form of piety and a strict rigoristic morality. Thus, it was in sharp opposition to the more tolerant ethics and the opulent religious ceremony favored by the dominant factions within the church, especially the powerful Jesuit order.
Beginning in the 1640s, the spiritual center of Jansenism was the convent of Port-Royal-des-Champs near Paris, where numerous nobles, royal judges, and intellectuals sympathetic to the movement made religious retreats. Almost from its beginning, Jansenism aroused the hostility not only of the Jesuits but also of the French government, which associated the Jansenists with various political opposition movements. In 1653 five propositions relating to predestination, supposedly found in Jansen's writings, were condemned by the pope. Led by the theologian and philosopher Antoine Arnauld, Saint-Cyran's protégé, and by the scientist and religious philosopher Blaise Pascal, the Jansenists vigorously defended themselves, claiming that the five propositions were not actually found in Jansen's treatise; at the same time they launched a counterattack against the Jesuits. Finally, in 1713, under pressure from King Louis XIV, 101 propositions in a treatise by another French Jansenist, Pasquier Quesnel (1634-1719), were condemned by the papal bull Unigenitus. (The king had already closed Port-Royal-des-Champs and had had the convent razed in 1709.)
During the 18th century, Jansenism maintained a strong appeal, especially among the French parish clergy. Hundreds of clergymen refused to accept the bull Unigenitus, calling instead for a church council to examine the issue independently of Rome. The movement also spread to other areas of Europe, including Spain, Italy, and Austria. In the royal courts of France, the Jansenists increasingly allied themselves with the Gallicans, who also disliked the Jesuits and who were opposed to all papal intervention in French internal affairs (see Gallicanism). The civil courts defended the Jansenists when certain bishops, supported by the royal government, attempted to deny them the last rites. A major political clash between the courts and the government developed over the issue in the 1750s. The greatest triumph of the Jansenist-Gallican faction came in the 1760s, when the courts forced the expulsion of the Jesuits from France. Thereafter, the movement declined in importance, although small groups of Jansenists survived into the 19th and 20th centuries.
Jansen became head of the Dutch theological college of Saint Pulcheria at Leuven University in 1617, professor of exegesis in 1630 and bishop of Ypres in 1636. He died of the plague just after completing his great work, the Augustinus, which, upon publication two years later, was condemned as heretical.