Enlightenment | Definition, Summary, Ideas, Meaning, History, Philosophers, & Facts (2024)

Enlightenment, a European intellectual movement of the 17th and 18th centuries in which ideas concerning God, reason, nature, and humanity were synthesized into a worldview that gained wide assent in the West and that instigated revolutionary developments in art, philosophy, and politics. Central to Enlightenment thought were the use and celebration of reason, the power by which humans understand the universe and improve their own condition. The goals of rational humanity were considered to be knowledge, freedom, and happiness.

A brief treatment of the Enlightenment follows. For full treatment, see Europe, history of: The Enlightenment.

The age of reason: human understanding of the universe

The powers and uses of reason had first been explored by the philosophers of ancient Greece. The Romans adopted and preserved much of Greek culture, notably including the ideas of a rational natural order and natural law. Amid the turmoil of empire, however, a new concern arose for personal salvation, and the way was paved for the triumph of the Christian religion. Christian thinkers gradually found uses for their Greco-Roman heritage. The system of thought known as Scholasticism, culminating in the work of Thomas Aquinas, resurrected reason as a tool of understanding. In Thomas’s presentation, Aristotle provided the method for obtaining that truth which was ascertainable by reason alone; since Christian revelation contained a higher truth, Thomas placed the natural law evident to reason subordinate to, but not in conflict with, eternal law and divine law.

The intellectual and political edifice of Christianity, seemingly impregnable in the Middle Ages, fell in turn to the assaults made on it by humanism, the Renaissance, and the Protestant Reformation. Humanism bred the experimental science of Francis Bacon, Nicolaus Copernicus, and Galileo and the mathematical investigations of René Descartes, Gottfried Wilhelm Leibniz, and Isaac Newton. The Renaissance rediscovered much of Classical culture and revived the notion of humans as creative beings, and the Reformation, more directly but in the long run no less effectively, challenged the monolithic authority of the Roman Catholic Church. For Martin Luther, as for Bacon or Descartes, the way to truth lay in the application of human reason. Both the Renaissance and the Reformation were less movements for intellectual liberty than changes of authority, but, since they appealed to different authorities, they contributed to the breakdown of the community of thought. Received authority, whether of Ptolemy in the sciences or of the church in matters of the spirit, was to be subject to the probings of unfettered minds.

The successful application of reason to any question depended on its correct application—on the development of a methodology of reasoning that would serve as its own guarantee of validity. Such a methodology was most spectacularly achieved in the sciences and mathematics, where the logics of induction and deduction made possible the creation of a sweeping new cosmology. The formative influence for the Enlightenment was not so much content as method. The great geniuses of the 17th century confirmed and amplified the concept of a world of calculable regularity, but, more importantly, they seemingly proved that rigorous mathematical reasoning offered the means, independent of God’s revelation, of establishing truth. The success of Newton, in particular, in capturing in a few mathematical equations the laws that govern the motions of the planets, gave great impetus to a growing faith in the human capacity to attain knowledge. At the same time, the idea of the universe as a mechanism governed by a few simple—and discoverable—laws had a subversive effect on the concepts of a personal God and individual salvation that were central to Christianity.