Jurist Samuel von Pufendorf made important contributions to the study of law in light of the political realities created in the aftermath of the Thirty Years' War. As a young student of ethics and politics, Pufendorf was impressed by the natural-law theory of Hugo Grotius. A faithful Lutheran all his life, Pufendorf's overriding concern was to harmonize the insights of early Enlightenment political thinking with Christian theology. In 1660 he was appointed professor of natural law at the University of Heidelberg. In 1667 he moved to the University of Lund, where he wrote his influential work, Of the Law of Nature and Nations, published in condensed form as The Duty of Man and Citizen According to Natural Law.
Pufendorf's primary contribution was his emphasis on the “sociality” of humankind as the foundation of the natural law. “Any man must, inasmuch as he can,” he wrote, “cultivate and maintain toward others a peaceable sociality that is consistent with the native character and end of humankind in general.” Sociability, however, is threatened by the fallen character of the human condition. “What would men's life have been like without a law to compose them?” he asks: “a pack of wolves, lions, or dogs fighting to the finish.” Hence God, the divine lawgiver, established laws to order human social life. As Pufendorf writes, “Just as the life of men would without society be similar to the life of the beasts, so the law of nature is chiefly based on the principle that social life is to be preserved among men.”
Pufendorf's theory is not without problems. As the Treaty of Westphalia sought to remove violent theological controversies from the public square, Pufendorf strove to desacralize politics by privatizing religion, helping to pave the way for the deistic philosophies of the later Enlightenment. Nevertheless, his impact was widespread. Locke, Rousseau, and Diderot all recommended his inclusion in law curricula, and Pufendorf greatly influenced Blackstone and Montesquieu. By way of these thinkers, Pufendorf was introduced to and utilized by American Founders such as Hamilton, Madison, and Jefferson as they formulated the political thought of the new Republic.