In general terms, the Enlightenment was an intellectual movement, developed mainly in France, Britain and Germany, which advocated freedom, democracy and reason as the primary values of society. It started from the standpoint that men's minds should be freed from ignorance, from superstition and from the arbitrary powers of the State, in order to allow mankind to achieve progress and perfection. The period was marked by a further decline in the influence of the church, governmental consolidation and greater rights for the common people. Politically, it was a time of revolutions and turmoil and of the overturning of established traditions.
The Enlightenment is the period in the history of western thought and culture, stretching roughly from the middle of the 17th century through the 18th century, characterised by dramatic revolutions in science, philosophy, society and politics. It culminates historically in the political upheaval of the French Revolution, in which the traditional hierarchical political and social orders (the French monarchy, the privileges of the French nobility, the political power and authority of the Catholic Church) were violently destroyed and replaced by a political and social order based on the ideals of freedom and equality for all. Even though France soon reverted to absolute monarchy, the French Revolution greatly influenced the subsequent development of political and social life in Europe.
The period also peaked with the establishment of the first republic in the New World settled by Europeans, whose "Founding Fathers" based their constitution and government on the liberal ideas of equality and religious tolerance delineated in the works of John Locke and Baron de Montesquieu.
The Enlightenment begins with the scientific revolution of the sixteenth and seventeenth centuries. The rise of the new science progressively undermines not only the ancient geocentric conception of the cosmos, but, with it, the entire set of presuppositions that had served to constrain and guide philosophical inquiry. The dramatic success of the new science in explaining the natural world, in accounting for a wide variety of phenomena by appeal to a relatively small number of simply mathematical formulas, promotes philosophy from an offshoot of theology, limited in its purposes and methods, to an independent force with the power and authority to challenge the old and construct the new.
The task of characterizing philosophy of the Enlightenment confronts the obstacle of the wide diversity of Enlightenment thought. The Enlightenment is associated with the French thinkers of the mid-18th century, the so-called philosophes, (Voltaire, Diderot, D'Alembert, Montesquieu, etc). The philosophes constitute an informal society of men of letters who collaborate on a loosely defined project of Enlightenment centered around the project of the Encyclopedia. Voltaire, perhaps the most influential figure of 18th-century French thought, was a deist and a great defender of religious tolerance. Diderot, an atheist, was the driving force behind the first grand effort to register, classify and systematise the huge amount of data gathered since the renewed interest in science and philosophy in the Renaissance in a single publication, the Encyclopedia.
In addition to the French, there was a very significant Scottish Enlightenment (Francis Hutcheson, David Hume, Adam Smith, and Thomas Reid) and a very significant German Enlightenment (die Aufklärung, key figures of which include Christian Wolff, Moses Mendelssohn, G.E. Lessing and Immanuel Kant). But all these Enlightenments were but particular centers in a diversified and varied intellectual development.
Kant defines “enlightenment” as humankind's release from its self-incurred immaturity; “immaturity is the inability to use one's own understanding without the guidance of another.” It is the process of undertaking to think for oneself, to employ and rely on one's own intellectual capacities in determining what to believe and how to act. Philosophers of this epoch from across the geographical and temporal spectrum tend to have a great deal of confidence in humanity's intellectual powers, both to achieve systematic knowledge of nature and to serve as an authoritative guide in practical life. This confidence is generally paired with suspicion or hostility toward other forms or carriers of authority (such as tradition, superstition, prejudice, myth and miracles), considered to challenge the authority of reason.
So, philosophy of the Enlightenment tends to stand in tension with established religion. The "faith" of the Enlightenment is that the process of enlightenment, of becoming progressively self-directed in thought and action through the awakening of one's intellectual powers, leads ultimately to a better, more fulfilled human existence.