Scientific Revolution Advances in scientific method , from a drawing by
Charles Nicolas Cochin. The Enlightenment was in large part an extension of the discoveries of
Nicolas Copernicus in the 16th century, which were not well known during his lifetime, and more so of the theories of
Galileo Galilei (1564–1642). Inquiries to establish certain
axioms and
mathematical proofs continued as
Cartesianism throughout the 17th century.
Gottfried Wilhelm von Leibniz (1646–1716) and
Isaac Newton (1642–1727) had independently and almost simultaneously developed the
calculus, and
René Descartes (1596–1650) the idea of
monads. British philosophers such as
Thomas Hobbes and
David Hume adopted an approach, later called
empiricism, which preferred the use of the
senses and
experience over that of
pure reason.
Baruch Spinoza took Descartes' side, most of all in his
Ethics. But he demurred from Descartes in ("On the Improvement of the Understanding"), where he argued that the process of
perception is not one of pure reason, but also the senses and
intuition. Spinoza's thought was based on a model of the universe where God and Nature are one and the same. This became an anchor in the
Age of Enlightenment, held across the ages from Newton's time to that of
Thomas Jefferson's (1743–1826). A notable change was the emergence of a
naturalist philosophy, spreading across Europe, embodied by Newton. The
scientific method – exploring experimental evidence and constructing consistent theories and axiom systems from observed phenomena – was undeniably useful. The predictive success of Newton’s theories culminated in his masterwork
Philosophiae Naturalis Principia Mathematica (1687). As an example of scientific progress in the
Age of Reason and the Enlightenment, Newton's example remains unsurpassed, in taking observed facts and constructing a theory which explains them
a priori, for example taking the motions of the planets observed by
Johannes Kepler to confirm
his law of universal gravitation. Naturalism saw the unification of pure
empiricism as practiced by the likes of
Francis Bacon with the axiomatic, "pure reason" approach of Descartes. Belief in an intelligible world ordered by a Christian God became the crux of philosophical investigations of knowledge. On one side, religious philosophy concentrated on
piety, and the omniscience and ultimately mysterious nature of God; on the other were ideas such as
deism, underpinned by the impression that the world was comprehensible by human reason and that it was governed by universal physical laws. God was imagined as a "Great Watchmaker"; experimental
natural philosophers found the world to be more and more ordered, even as machines and measuring instruments became ever more sophisticated and precise. The most famous French natural philosopher of the 18th century,
Georges-Louis Leclerc de Buffon, was critical of this natural theology in his masterwork
Histoire Naturelle. Buffon rejected the idea of ascribing to
divine intervention and the "supernatural" that which science could now explain. This criticism brought him up against the
Sorbonne which, dominated by the
Roman Catholic Church, never stopped trying to censor him. In 1751, he was ordered to redact some propositions contrary to the teaching of the Church; having proposed 74,000 years for the
age of the Earth, this was contrary to the Bible which, using the scientific method on data found in
biblical concordances, which conflicted with contemporary biblical chronologies. The Church was also hostile to his no less illustrious contemporary
Carl von Linné, and some have concluded that the Church simply refused to believe that order existed in nature.
Individual liberty and the social contract This effort to research and elucidate universal laws, and to determine their component parts, also became an important element in the construction of a philosophy of
individualism, where everyone had rights based only on
fundamental human rights. There developed the philosophical notion of the thoughtful
subject, an individual who could make decisions based on pure reason and no longer in the yoke of custom. In
Two Treatises of Government,
John Locke argued that
property rights are not held in common but are totally personal, and made legitimate by the work required to obtain the property, as well as its protection (recognition) by others. Once the idea of
natural law is accepted, it becomes possible to form the modern view of what we would now call
political economy. In his famous essay
Answering the Question: What is Enlightenment? (),
Immanuel Kant defined enlightenment thus: Enlightenment philosophy was thus based on the realities of a systematic, ordered and understandable world, which required Man also to think in an ordered and systematic way. As well as physical laws, this included ideas on the laws governing human affairs and the
divine right of kings, leading to the idea that the monarch acts with the consent of the people, and not the other way around. This legal concept informed
Jean-Jacques Rousseau's theory of the
social contract as a reciprocal relationship between men, and more so between families and other groups, which would become increasingly stronger, accompanied by a concept of individual inalienable rights. Among atheist Enlightenment thinkers, appeals to divine authority were rejected in favor of secular reasoning. The Enlightenment redefined the ideas of liberty, property and rationalism, which took on meanings that we still understand today, and introduced into political philosophy the idea of the free individual, liberty for all guaranteed by the State (and not the whim of the government) backed by a strong
rule of law. To understand the interaction between the Age of Enlightenment and the Enlighteners, one approach is to compare
Thomas Hobbes with
John Locke. Hobbes, who lived for three quarters of the 17th century, had worked to create an ontology of human emotions, ultimately trying to make order out of an inherently chaotic universe. In the alternate, Locke saw in Nature a source of unity and universal rights, with the State's assurance of protection. This intellectual shift during the 17th and 18th centuries reflected contrasting views of the relationship between humanity and nature. This resulted, in France, in the spread of the notion of human rights, finding expression in the 1789
Declaration of the Rights of Man and of the Citizen, which greatly influenced similar declarations of rights in the following centuries, and left in its wake global political upheaval. Especially in France and the United States,
freedom of expression,
freedom of religion and
freedom of thought were held to be fundamental rights.
Social values and manifests Representation of the people The core values supported by the Enlighteners were
religious tolerance, liberty and
social equality. In England, America and France, the application of these values resulted in a new definition of
natural law and a separation of
political power. To these values may be added a love of nature and the cult of reason.
Philosophical goals '', an encyclopaedia of 18th-century anticolonialism The ideal figure of the Enlightenment was a philosopher, a
man of letters with a social function of exercising his reason in all domains to guide his and others' conscience, to advocate a
value system and use it in discussing the problems of the time. He is a committed individual, involved in
society, an (
Encyclopédie; "Honest man who approaches everything with reason"), (
Diderot, "Who concerns himself with revealing error"). The rationalism of the Enlightenment was not to the exclusion of aesthetics. Reason and
sentiment went hand-in-hand in their philosophy. The thoughts of Enlightenment philosophers were equally capable of intellectual rigour and sentimentality. Despite controversy about the limits of their philosophy, especially when they denounced black
slavery, many Enlightenment philosophers criticised slavery, or
colonialism, or both, including
Montesquieu in ''
De l'Esprit des Lois (while keeping a "personal" slave), Denis Diderot in Supplément au voyage de Bougainville, Voltaire in Candide and Guillaume-Thomas Raynal in his encyclopaedic Histoire des deux Indes'', the very model of 18th-century
anticolonialism to which, among others, Diderot and
d'Holbach contributed. It was stated without any proof that one of their number,
Voltaire, had shares in the
slave trade.
Encyclopaedic goals At the time, there was a particular taste for compendia of "all knowledge". This ideal found an instance in Diderot and d'Alembert's ("Encyclopaedia, or Systematic Dictionary of the Sciences, Arts, and Crafts"), usually known simply as the
Encyclopédie. Published between 1750 and 1770 it aimed to lead people out of ignorance through the widest dissemination of knowledge.
Criticism The Enlightenment was, for all its existence, pulled in two directions by opposing social forces: on one side, a strong
spiritualism accompanied by a traditional faith in the religion of the Church; on the other, the rise of an
anticlerical movement, critical of the differences between religious theory and practice, which was most manifest in France. Anticlericism was not the only source of tension in France: some noblemen contested monarchical power and the upper classes wanted to see greater fruit from their labours. A relaxing of morals fomented opinion against absolutism and the Ancient Order. According to Dale K. Van Kley,
Jansenism in France also became a source of division. The French judicial system showed itself to be outdated. Even though commercial law had become codified during the 17th century, there was no uniform, or codified, civil law.
Voltaire This social and legal background was criticised in works by the likes of
Voltaire. Exiled in England between 1726 and 1729, he studied the works of John Locke and Isaac Newton, and the English monarchy. He became well known for his denunciation of injustices such as those against
Jean Calas,
Pierre-Paul Sirven,
François-Jean de la Barre and
Thomas Arthur, comte de Lally. Enlightenment philosophy saw its climax in the middle of the 18th century. For Voltaire, it was obvious that if the monarch can get the people to believe unreasonable things, then he can get them to
do unreasonable things. This axiom became the basis for his criticism of Enlightenment philosophers, and led to the basis of
romanticism: that constructions from pure reason created as many problems as they solved. According to Enlightenment philosophers, the crucial point of intellectual progress consisted of the synthesis of knowledge, enlightened by human reason, with the creation of a sovereign moral authority. A contrary point of view that developed, arguing that such a process would be swayed by social conventions, leading to a "New Truth" based on reason that was but a poor imitation of the ideal and unassailable truth. The Enlightenment thus tried to find a balance between the idea of a "natural" liberty (or autonomy) and the freedom
from that liberty, that is to say, the recognition that the autonomy found in nature was at odds with the discipline required for pure reason. At the same time, with various monarchs' reforms, there was a piecemeal attempt to redefine the order of society, and the relationship between monarch and subjects. The idea of a natural order was equally prevalent in scientific thought, for example, in the works of the biologist
Carl von Linné.
Kant In Germany,
Immanuel Kant (like Rousseau, defining himself among Enlightenment philosophers) heavily criticised the limitations of pure reason in his work
Critique of Pure Reason (), but also that of English empiricism in
Critique of Practical Reason (). Compared with the rather subjective
metaphysics of Descartes, Kant developed a more objective viewpoint in this branch of philosophy.
Adam Smith Great thinkers at the end of the Enlightenment (
Adam Smith, Thomas Jefferson and even the young
Goethe) adopted into their philosophy the ideas of self-organising and evolutionary forces. The Enlightenment stance was then presented with reference to what was seen as a universal truth: that Good is fundamental in nature, but it is not self-evident. On the contrary, it is the advance of human reason that reveals this constant structure.
Romanticism is the exact opposite of this stance.
Aestheticism by
Étienne-Louis Boullée, 1781 {{blockquote| This resulted in reflections about
urbanism. The Enlightenment model town would be a joint effort between public provision and sympathetic architects, to create administrative or utilitarian buildings (town halls, hospitals, theatres, commissariats) all provided with views, squares, fountains, promenades, and so on. The French
Académie royale d'architecture was of the opinion that ("The beautiful is the pleasant"). For
Abbé Laugier, on the contrary, the beautiful was that which was in line with rationality. The natural model for all architecture was the log cabin supported by four tree trunks, with four horizontal parts and a roof, respectively
columns,
entablature, and
pediments. The model of a
Greek temple was thus extended into the décor and the structure. This paradigm resulted in a change of style in the middle of the 18th century:
Rococo was dismissed,
Ancient Greece and
Palladian architecture became the principal references for
neoclassical architecture. , designed by Thomas Jefferson. The
University of Virginia, a
UNESCO World Heritage Site, was founded by
Thomas Jefferson. He drew up plans for parts of the campus based on the values of Enlightenment philosophers. The
Place Stanislas at
Nancy, France is the focus of an array of neoclassical urban buildings, and has been on the UNESCO
List of World Heritage Sites in France since 1983, as well as several other sites in the town, such as the
Place de la Carrière and the
Place d'Alliance, the administrative centre of the time.
Claude Nicolas Ledoux (1736–1806) was a member of the Académie d'Architecture was without doubt the architect whose projects best represented the utopian, purely rational environment. (That which is rational, and thus based in the understanding of nature, cannot be at the same time utopian.) Starting in 1775 he built the
Royal Saltworks at Arc-et-Senans, a very industrial city in
Doubs. The bourgeoise had learned nothing from Enlightenment philosophers, even though they saw Rousseau, Montesquieu and Kant as honest men who approved of the "élite": a vague concept, and one of which Enlightenment philosophers amongst others disapproved. There was considerable coverage in the English and French Press, but less so in Germany and Italy; in Spain and Russia very few knew about it save a few intellectuals, senior officials and grand families participated in the movement. The mass of the people could not care less: the vast majority of the common people, even in France, had never heard of Voltaire or Rousseau. Nevertheless, Enlightenment philosophers had disrupted the old certainties. This did not stop at social and political upheaval: the Enlightenment inspired a revolutionary generation, which is not to say they explicitly encouraged the
French Revolution of 1789. ==Key figures==