On Free Will (De Libero Arbitrio)

By the early 1520s Erasmus was under pressure from Catholic authorities, including Pope Adrian VI and the English court, to declare himself against Luther, whose followers often claimed him as an ally. He chose the freedom of the will because it was a doctrine he believed he could discuss without defending abuses of the Church, and because Luther had stated a strong position on it. He wrote reluctantly and described himself as an inquirer, not a combatant. Historians generally read the work as a deliberate, limited intervention that sought to establish distance from Luther without endorsing the papal party's methods.

He defines free will as a human power to apply oneself to what leads to eternal salvation or to turn away from it. He maintains that grace initiates, accompanies, and completes the work of salvation, while the human will cooperates and is not merely passive. He supports this by marshaling biblical commands and exhortations, which he says make little sense if humans have no capacity to respond. He also holds that Scripture on the point is obscure and that confident assertion is unwise. The position is semi-Pelagian in the eyes of critics, though Erasmus insists on grace's priority.

Luther answered in 1525 with De servo arbitrio, a long and forceful rebuttal arguing that, since the fall, the human will is bound, that salvation depends wholly on God, and that Scripture is clear on the matter. He mocked Erasmus's skepticism, saying that a Christian must make assertions, and treated the question as the heart of the Reformation, praising Erasmus only for choosing the real issue. Their exchange is the best known between a humanist and a reformer, and it marks the point at which the humanist movement and the Protestant Reformation visibly diverged.

He wrote Hyperaspistes in two parts, in 1526 and 1527, a lengthy defense of his treatise against Luther's reply. It is longer than the original and more polemical in tone, which shows the cost the controversy had for his reputation as a peacemaker. Readers who want to understand how Erasmus defended his position on grace, Scripture's clarity, and the authority of the Church's tradition should read it alongside On Free Will, since the later work addresses points that the first leaves tentative.

It proceeds by close attention to scriptural texts, comparison of passages, and appeal to the interpretive tradition of the Fathers, with a rhetorical stance of modesty in place of scholastic definition. Erasmus presents himself as preferring to doubt where the Church has not defined, a stance grounded in a skeptical strand of Academic thought that he cites approvingly. Scholars see this as continuous with his wider humanist program of philology and piety, even though in this case the program led him to a position at odds with Luther. The treatise is therefore both a theological and a methodological statement.

A common misreading takes Erasmus as a defender of unqualified human autonomy, or as an opponent of grace. His text insists that grace is primary and that the will's role is subordinate and cooperative. Another misreading treats the work as a strictly Catholic polemic in the style of Luther's other opponents, when its tone and aims are more moderate and exploratory. A third reads it as indifference to doctrine, when Erasmus argues that some matters should be left undefined out of reverence for Scripture's obscurity.