The period of Enlightenment refers to the European culture of the 18th century. The People of Enlightenment believed the almightiness of human knowledge and defied the tradition and the pre-established thoughts of the past. this is the period in which the humans became overconfident in the human Reason an rationality. Philosophers and Scientists committed the fallacy of argumentum ad ignorantiam. Anything which cannot be understood by rational knowledge and the current status of sciences was defied as meaningless or superstitious. Philosophy became very popular among the intellectuals and people read philosophical opera. However, the general concerns were about the practical use of our knowledge. In other words,
The Two Fundamental Characteristics of the Philosophy of Enlightenment are:
1) faith in the European Reason and human rationality to reject the tradition and the pre-established institutions and thoughts;
2) Search for the practical, useful knowledge as the power to control nature.

John Locke is considered generally as the founder of Enlightenment movement in philosophy. However, in England, both characteristics of Enlightenment, namely the defiance of the tradition and the search for the knowledge as the practical, useful power to control nature, were not so emphatically visible due to the nationality and the social conditions in England. So it is generally agreed that the philosophy of Enlightenment will be divided into a) the Philosophy of Enlightenment in England, that in France and Germany. Therefore, a) is normally called as the British Empiricism and it s development. Distinguished from this, we consider the Philosophy of Enlightenment and its movement with the emphasis of the phases in France and Germany.

1. The relation of Descartes to the philosophy of Enlightenment
In France and in England, all the philosophical thoughts from the middle of 17th century through the 18th century were under Descartes's influences.
Fontenelle (1657-1757)
The admirer of Descartes' physics and his radical rationalism threatened the Christianity and the established Church. Fontenelle's philosophy did not accept the Cartesian spiritualism and overemphasized the positive elements of the Cartesian philosophy. Thus, Fontenelle merely criticized the Ancient oracles as superstition, but this was immediately applied to the miracles of Christianity.
Bayle (1647-1706)
Starting with the Cartesian rationalism, Bayle considered that to believe in Christianity means to abandon Reason and the human rationality and to surrender to the miraculous phenomena. The opposition between philosophy (rationalism) and religion set up by Bayle created an anti-religious movement against Christianity as well as prepared for the development of the 18th Century philosophy.
The Enlightenment Movement in France is a synthesis of the Cartesian philosophy of the mechanistic understanding of nature and the British Empiricism.
In the 17th century, British philosophers such as Bacon, Hobbes and Locke came to France and were strongly influenced by the French Philosophies. In the 18th century, the French philosophers visited England and were strongly influenced by the British Empiricism and advocated empiricism rather than idealism in France upon their return.

2. The influences of British Empiricism on the French Philosophies
The most conspicuous example of the philosophers who were influenced by the British Empiricism was Voltaire.

Voltaire (1694-1778)
Voltaire was a French man of thought who was most strongly influenced by British Empiricism and attacked the philosophers of Continental Rationalism.
Voltaire was the author of Candid, which made fun of Leibniz' optimism.
Voltaire attempted to refute Descartes' metaphysics
on the basis of Locke's Empiricism
and
attacked Descartes' physics,
employing Newton's mechanics.
Voltaire mocked Descartes' innate ideas by referring to Locke's theory of the empirical origin of ideas which refuted the innate idea. Following Locke, Voltaire, too, considered man's desire to pursue one's happiness as inborn.
Voltaire further maintained that
while Descartes created a novel about the human spirit,
Locke wrote the history of the human spirit.
Voltaire praised Locke in how he was able to explain the origin and the process of the development of human spirit.
Voltaire accused of Descartes in the following points:
1. Descartes by reducing physics to geometry denied the absoluteness of motion and argued for its relativity (i.e. motion is no other than the change of place, in other words, a portion of matter changes its place in relation to the portion of the other matter which is immediately touched to the former)
2. Descartes did not recognize gravitation (=the weight as the unique quality) by reducing matter to extension
3. Descartes by failing in recognizing the universal gravitation had to explain by the celestial vortex the motions of the celestial bodies. Thus Descartes explained the motion of solar planets by a heliocentric vortex.
In that sense he did not disagree with Copernicus.
In contrast, Newton proposed the universal gravitation by which he explains all the motions of celestial bodies.
Voltaire became Newton's follower in physics and astronomy. Against the universal gravitation being a hidden(occult) power, Voltaire argued that the cosmic turbulence (vortex) is more a hidden power than gravitation because the law is verified and the phenomena are explained.
In his letter in 1728 Voltaire writes,
"When a French went to London, he discovers a lot of things different. So are there a big difference in philosophy. When he was in Paris, the universe is full of something like turbulent ether, upon his arrival in London he discovers that the same space is empty."
Following the fashion of his time, Voltaire considers a systematic approach less valuable than a fragmental expression of insights.
Voltaire was successful in making philosophy more popularized (journalistic).
Voltaire discussed on may topics such as on God, freedom, immortality of soul.
Voltaire holds that it is the true religion that one loves God and loves others like one's own siblings and that less dogmas it has, the better and true it becomes.
Thus Voltaire fought against the traditional established Christianity.
On the other hand, he criticized d'Hollbach's La Systeme de la nature, and attacked Pascal's Christianity.
Influenced by British Deism, Voltaire maintained that religion must be a moral, rationalistic natural religion. He did not support the cosmological and teleological argument and yet considered the moral argument for the existence of God to be most useful.
Voltaire maintained that without God morality is not possible, therefore God must exist. "If God did not exist, we must invent God!"
Voltaire considers that it is not possible to theoretically demonstrate the immortality of soul and yet without the immortality of soul, morality is also not possible.(VERY KANTIAN)
Voltaire contends that the basis of metaphysics consists in morality and
that the obscurity and incompleteness of metaphysics will be clarified by morality.
In his early period, Voltaire held the freedom of will, but abandoned it in his later years as meaningless and recognized only the freedom of action.
According to Voltaire, freedom is when one can do what one wants to do.
Whether or not what one wants is free, the answer is not, but what wants to desire is to necessarily desire. Otherwise, we desire to do something without reason or cause, that is impossible.Thus Voltaire proposed the psychological determinism.
Regarding the problem of evil, he was optimistic, but after Lisbon's earthquakes Voltaire abandoned optimism.
In relation to politics and society, Voltaire insisted freedom of reason, freedom of consciousness and particularly the freedom of research which contributed the further development of the contemporary european culture.
Voltaire was the representative of the 18th century Enlightenment Spirit and enormously influenced the intellectuals of the days, according to Thomas Carlyle.
Du Bois-Reymond said,
"The reason why we do not consider Voltaire as a very important Enlightenment philosopher is because we unconsciously and implicitly have been a Voltaire ourselves. What Voltaire had fought and won such as culture, freedom of spirit, the dignity of humanity and justice have become some of the essential elements of our natural everyday life today."
Voltaire was highly treated by Friedrich the Great at Prussian Sansoun Palace as an important guest.
There are two poems of Voltaire;
Le mondaine
Defense du mondain ou l'apologie du luxe
He loved gambling!
Lettres sure les Anglais or Lettres philosophiques(1734)
Elements de la philosophie de Newton
Dictionnaire philosophique
La philosophie ignorant
Candid

Montesquieu (1689-1755)
Montesquieu went to England and was also influenced by John Locke. He was deeply impressed by Locke's three division of the government. His main work is
L'esprit des lois (1748)
Recognizing the peculiarity and uniqueness of each nation, Montesquieu attempted to explain the legal system of the each nation from the geographic conditions and the social conditions of the given nation. In stead of seeking the foundation of the legal system of a certain nation in the rational, universal principles, Montesquieu tried to find the causes of the legal system of a given nation in the particular climates, the nature of soil, the largeness of the land, the living conditions of the people, religion, passions of the people, the degree of wealth and poverty, population and the historical conditions such as customs. He emphasized the uniqueness and the accidental nature of the legal system of a given nation.

The differences of the systems of government are due to the peculiarity of the given nation.
the republic = the subject has the right to govern
all the subjects = democracy
a portion of the subjects = aristocracy
the monarchy = the government by one ruler based on the constitution
the constitutional monarchy
the despotism = the government by one ruler by his will

There are the basic passions which motivate each of these forms of government

the republic = virtue
the monarchy = honour

And the size of a country will affect the nature of the government. etc.

3. Radical Empiricism in France

Condillac (1715-1780)
Condillac developed the Locke's empiricism to an extreme. While in England the common sense plays an important role and balances philosophical ideas, once those ideas were transferred to the Continent, they took up very radical forms.
While Locke denied the Cartesian innate ideas' existence and considered our mind to be "tabula rasa," he was influenced by Descartes and distinguished experience into sensation (external) and reflection (internal) whereby sensation precedes reflection but the latter does not come from the former.
On the other hand, Condillac held that everything including reflection comes from sensation, that is a radicalization of Locke's thought about the origin of the internal perception. Sensualism.
Condillac's major work is
Traité des sensations

4. Encyclopaedists

In France the editing and publication of the Encyclopedia, a comprehensive book of all the books about wisdom of all humanity, was attempted for the first time in the West. Many of the contemporary contributed to drafting the manuscripts. Voltaire, Rousseau and Helvetilus contributed.
The basic motive of this edition was the denial of the past and the resistance against church's authority.
The leading motives were 1) nature,
2) reason
3) humanity.
The encyclopedists were considered the representatives of the Enlightenment Movement.

Diderot (1713-1784)

Pnsées philosophiques
Trailté de l'interprétation de la nature
Rêve de d'Alembert
Lettre sur eles aveugles
Lettre sur les sourds et les muets

Diderot devoted himself to the editing of the Encyclopedia for more than twenty years. At the first half of the eighteenth century, Voltaire occupied the leading position among the intellectuals, at the second half of the eighteenth century, Diderot played the leading role. Diderot was multi disciplinary and possessed a wide range of knowledge, but he never had a consistent philosophical thoughts.
His thoughts were usually divided in three periods, that of deism, that of skepticism and that of naturalism.
At the first period, Diderot attacked both the atheism and the theism from the point of the deism.(= rationalistic)
At the second period, Diderot was influenced by Bayle and became a skeptic. "I do not know whether or not You, God, exist, but let me behave myself as if You did exist!"
At the period of naturalism, Diderot held monism and said that the rule of mathematics ended and the rule of the natural sciences will begin. This means that against the simplistic mechanistic view of nature, Diderot sought to discover the principle based on the organism like Leibniz. He regarded the observation of nature and experiment as very important and objected the distinction (like Descartes) between mind and matter. Diderot said that a stone senses. Diderot adored nature and considered that nature be the ultimately Divine.

d'Alembert (1717-1783)
d'Alembert was Madame de Tencin's abandoned son. d'Alembert was a mathematician and edited the Encyclopedia together with Diderot. d'Alembert wrote the Introduction (Discours préliminaire) in which he made detailed distinctions among the human knowledge, although in principle he got them from Bacon's distinctions. The major difference consists in the fact that d'Alembert made the faculty of imagination as that of fine-arts rather than that of poesy, as Bacon did.
d'Alembert contended that the progress of human cognitive faculties goes from memory through reason to imagination rather than memory, imagination to reason.
the official title of Encyclopedia is
Encyclopédie ou Dictionnaire raisonné des sciences et des arts
Bacon did not recognize the value of mathematics, d'Alembert considered mathematics as a part of natural sciences.
d'Alembert was skeptic regarding the nature of knowledge and its object. We are not able to recognize both nature and spirit ultimately. After Diderot became a naturalistic materialist and consequently the content of Encyclopedia, too, became materialistic, d'Alembert quit working for Encyclopedia as the co-editor.
His main work (apart of Encyclopedia) is
Éléments de philosophie.
D'Alembert was invited by Friedrich II, but stayed in Paris and lived the life of poverty.

5. Materialists

La Mettrie (1709-1751)
La Mettrie was born in Sant-Malo and was a military physician. La Mettrie published Histoire naturelle de l'âme (1745)(which advocated the materiality of spirit and its reducibility to matter) and lost the job. Three years later, he published a more radical book, called L'homme machine (1746). As a consequence, he was purged from France, and then from Holland and took refuge to Friedrich II in Prussia. Friedrich the Great warmly treated La Mettrie and appointed to the Academy and made him his personal consultant.
In ethics, La Mettrie took the position of hedonism.

d'Holbach (1723-1789)
d'Holbach was born in Pfalz, Germany. He went to Paris and was naturalized to France. His main work was
Système de la nature ou de lois du monde physique et due monde moral (1770)
At his early years, he contributed to Encyclopedia on Chemistry, but later he was deeply influenced by Diderot and became a materialist philosopher. His residence on rue Saint-Roch in Paris became the central salon of the free thinkers and the intellectuals.
Any supernatural thing exists only in our imagination. What really exists is matter and its motion. This matter and its motion are governed by the strict natural laws. Descartes mechanistic view of nature was extended to the entire universe.

Buffon (1707-1788)
Buffon was a natural historian and was also a materialist. He held that a living organism changes under the influences of its environment. The forerunner of the evolutionist before Lamarck and Darwin.

THE ANTI-RATIONALIST TREND AND ENLIGHTENMENT

JEAN JACQUES ROUSSEAU (1712-1778)

Jean Jacques Rousseau had a double relationship with the Enlightenment Movement.
On the one hand, for example,
Kant defined Enlightenment as "der Ausgang des Menschen aus seiner selbstverschuldeten Unmündigkeit." (the exist out of the humans' adolescence which they had imposed upon themselves). This definition is the one in a wider sense. In this sense,
Rousseau was certainly one of the Enlightenment philosophers.
On the other hand,
in its narrower sense, on the other hand, the Enlightenment means the almost blind faith in the almightiness of human Reason.
In this sense, Rousseau was against the Enlightenment in that Rousseau rejected the tyranny of Reason and advocated the return to nature and the revival of inner feeling.
Rousseau occupied a very unique position in the history of philosophy in the 18th century: On the one hand, Rousseau was a product of the 18th century Europe in that Rousseau with faith in the human dignity and intelligence was the philosophical father of the French Revolution. Its motto was to return to nature, regaining the natural rights of "liberty, equality and fraternity."
Rousseau was the successor of the non-rational tradition of Pascal in which the way of thinking alternative to rationalism was developed in curving the power of the European Reason.
Rousseau was born in Geneva in a protestant family (he was threatened by the catholic and later converted to Catholicism, but) and was constantly threatened by the prosecution phobia. E.g., Hume helped found Rousseau a job, which he could not kept and fled for France again.
Rousseau sought many different occupations, but he never kept any for any period of time worth mentioning. As he was in Paris, he got acquainted with Diderot and contributed to Encyclopedia. Rousseau was 37 years of age.
In the same year, the academy of Dijon made a prizing wining contest for a paper under the title "Le rétablissement des sciences et des arts a-t-il contribué à épurer les moeurs?" (Did the re establishment of sciences and arts contribute to purifying the morals?) Looking at this title, Rousseau was extremely excited and immediately grasped by intuition that culture (sciences and arts) was the clusters of the meaningless Reason and merely the world of the forms.
The culture is the world of externality which distorts the genuine, original human nature. Against it,
there is a world of internality which is more precious and quite different from the world of externality. this is the world of our natural sentiment. Therefore, Rousseau said in the prize winning paper, Discours sur les sciences et les arts, that the culture did not contribute. For sciences and arts only deal with the external elements of the human existence. Not only it is superficial, but also it harms the inner world of the human nature.
Rejecting the culture of Reason which the Encyclopedists advocated, Jean Jacques Rousseau urged that we must Return to Nature. The nature here stipulated is the nature without corruption, the nature of naivety, the purity of the natural humans.
His paper won the prize and Rousseau became instantly famous.
Five years later, the same academy of Dijon publicized a prize-wining paper with the theme, Quelle est l'origine de l'inégalité parmi les hommes, et si elle est autorisée par la loi naturelle? Rousseau responded with his article titled, discours sur l'origine de l'inégalité parmi le hommes, and radically criticized the social and political conditions of the time, just as he did in the first paper the wrong culture and the culture of Reason.
In the article, Rousseau advocated the society in the state of nature, the society with no class-distinctions, no distinction of the master and the servant.
The social inequality, according to Jean Jacques Rousseau, was produced by the development of agriculture and its accompanying the concept of private possessions. Some people started to publicly demand their territories by setting up the fences, while the other ignorant people believed them. from this, the right of property and its digression were brought into the society and the inequality of the rich and the power as well as the distinction of the master and the servant was established. The equality and freedom of the state of nature was destroyed by the social institutions of inequality and constraint. "We were born free and equal. Now we are all chained!"
Although Rousseau did not advocate that there were the state of nature historically in fact, but the state of nature is the state of "ought" or that of the Ideal, toward which we must return and we must recover our own authentic being by recovering those natural rights of equality and freedom. This paper did not get the prize.
While these two articles criticized the spiritual conditions and the social institution of the time, the following two opera were so-to-speak to advocate the positive Ideals for reconstruction of culture and society:
Émile
Contrat social
The Social Contract was one of the most influential publications in the social-political philosophy in the Contemporary European history. While Montesquieu dealt with the political institutions prevalent in the time, Rousseau was concerned about the Ideal conditions and the principles of what the government ought to be. : "Je cherche le droit et la raison, et ne dispute pas des faits." (I search the right and the reason and do not dispute about the facts!)‹Contrat Social Book I, § 5
"Il faut savoir ce qui doit être pour bien juger de ce qui est." (We must know what ought to be in order to judge what is.)‹Émile, Book V
According to Jean Jacques Rousseau, the right of governance is not given to the monarch by the Divine Power advocated by Filmer, nor is established by the contract between the despot and the subject like that of Hobbes' theory in Leviathan, but it is due to the social contract by which the people establish a nation. The selection of the monarch was done after the establishment of the nation by the social contract and it means that the subject entrust one person to rule for their sake. At the initial social contract, the people give up their original natural right of freedom for the spiritual unity as the civil state is born.
The ultimate source of the power of the civil state consists in the general will (la volonté générale). However, this general will is to be distinguished from the will of all (la volonté de tous). The will of all is the aggregate totality of all the individuals' wills each of which seeks each individual's personal profit. The general will aims, as the will of all people, at the happiness of everybody in the society.
Each of the members of the society loses the freedom as the natural right, in stead he or she gains the civil freedom determined by the general will. And under the civil laws, each individual is guaranteed its right for property and the right for equality. The genuine possessor of the right of governance is the subject, whereby the civil law is the expression of the general will
the sole object or purpose of which is the establishment and maintenance of freedom and equality.
In the genuine civil state, the people are to be forced to be free. The possibility of the state religion is also considered, It is the religion which believes in god and the final judgment.
Jean Jacques Rousseau wrote an article for Encyclopedia on the political economy.
In La nouvelle Héloise, Rousseau defended the rights of our inner soul and advocated the sacred nature of marriage.
Émile is titled as Émile ou de l'éducation (Émile or on Education) and this opus deals with the problem of education. John Locke also influenced Rousseau in this respect. It is a story about the brilliant tutor's educating the child called Émile and later having him married to Sophie.
At its beginning, Rousseau writes,
Tout est bien, sortant des mains de l'auteur des choses, tout dégénère entre les mains de l'homme. (Everything is good as it departs from the hand of the Creator, but as soon as it enters in the hands of the human, everything degenerates.) Rousseau maintains that education must be left to nature and things themselves.
Dans l'ordre naturel, les hommes ´tant tous égaux, leur vocation commune est l'état d'homme, et quiconque est bien élevé pour celui-là ne peut mal remplir ceux qui s'y rapportent. ..Avant la vocation des parents, la nature l'appelle à la vie humaine. Vivre est le métier que je veuxx lui apprendre. En sortant de mes mains, it ne sera, j'en conviens, ni magistrat, ni soldat, ni prêtre; it sera premièrement homme. (In the order of nature, all the humans are equal and their common vocation is to be human. And as long as one is properly educated, there must be nothing being human which one cannot do. ...Before the vocation of parenting, nature demands him (Émile) the truly human life. To live is the very means which I want him to learn. I am convinced that Émile leaving my hands, will neither a lawyer, a soldier, nor a priest. He will be above all human.) This is Rousseau's ideal of education.
The only way to educate a child toward freedom is, according to Rousseau, to educate him or her by freedom. We must assist that the one who is to be educated will educate himself or herself. We must not constrain the child.
Émile shall be educated by nature, not by books (only a little bit of astronomy, geography and chemistry are sufficient.). Émile shall be trained for handwork, i.e., carpentry. That is enough for training of reason.
For the training of heart, first the sentiment of pity, then of gratefulness, then that of love for humankind. And virtue which is the power to control oneself is to be taught.
Rousseau said,
"Ma régle de me livrer au sentiment plus qu'à la raison est confirmée par la raison même." (My regulation to depend on sentiment rather than reason is confirmed by reason itself.)‹Émile, Book IV
Another important point for the education is that Émile shall not be educated for religion until much later an age. Rousseau's religion may be called the natural religion.
"J'aperçois Dieu partout dans ses oeuvres; je le sens en moi, je le vois tous autour de moi; mais sitôt que je veux le contempler en lui-même, sitôt que je veux chercher où il est, ce qu'il est, quelle est sa substance, it m'échappe." (I perceive God everywhere in His works; I sense Him in me, I see Him in everything other than myself; however, as soon as I want to contemplate Him in myself, as soon as I want to search where He is, what He is, What is His substance, He escapes me.)‹Émile, Book IV
Thus, God, to Rousseau, is not rationally comprehensible, but He can only be intuitively grasped.
He was chased by the orthodox Christians, was objected by atheistic materialists.
The French revolution was motivated by the philosophical ideas advanced by Rousseau. Robespierre made his system of Convention (National Assembly) on the basis of the principle of Rousseau's Contrat social. The Strum und Drang Movement in Germany (of Goethe and Schiller) was also influenced by Rousseau. Kant was also deeply moved by Rousseau's Émile, too.

The German Enlightenment Movement

Thomasius (1655-1728)
(Omitted)

Christian Wollf (1679-1754)
Christian Wolff is the most important philosopher in the German Enlightenment Movement and was known for the systematization and vulgarization of Leibniz's philosophy and an important bridge to Kant's early dogmatic period (Kant was a Wolffean). Wolff did not accept Leibniz' notion of monad which Wolff interpreted as material atoms, as well as Leibniz' the principle of pre-established harmony which Wolff admitted only to the mind-body relationship,
(Omitted)

Reimarus (1694-1768)
Reimarus fought against both atheism and the theology of revelation at the same time.
(Omitted)

Lessing (1729-1781)
Lessing is considered as the most beautiful blossom of the German Enlightenment. Lessing's contribution in the philosophy of religion consists in
1) interpret the trinity-unity more speculatively
2) apply Leibniz' notion of development to the pre-established religion and theology.
In this sense, Lessing anticipates Hegel's philosophy.
(Omitted)

Moses Mendelssohn (1729-1786)
is considered as one of the most beautiful intellectuals of Enlightenment. He was a grandfather of Felix Mendelssohn-Baltordi, the famous Romantic composer who revived Johann Sebastian Bach and his music. At that time, Moses Mendelssohn was better known and more highly respected than his contemporary, Immanuel Kant.
(Omitted)

Tetens (1736-1805)
Tetens established the division of Thinking, Senses and Will.
(Omitted)