Eighteenth-century people emphasized the idea of natural right: Nature and its laws became the basis of all the vindications made by literate people in private correspondence, novels or treatises. The concept of natural right was foreign to French jurist tradition, but started to arise from 1771 through literature, rather than juridical treatise. Finding its roots in the Renaissance, the modern concept of natural right refers to human nature, and especially human nature before the creation of the State. Therefore, ‘the only laws that they recognized were the unchanging laws of nature’ and citizens did not need to have a constitution as they were governed by Nature.
Hugo Grotius was the first philosopher to develop the natural right in relation with international law and commercial law. He was also the first to develop the idea of social contract, stressing the idea that, with the natural rights, people are under their own jurisdiction, a concept linked with the questioning of the legitimacy of the Catholic Church. In Leviathan (1651), Thomas Hobbes combines the concept of ‘state of nature’ with the natural right theory and offers a very detailed contract theory, arguing that there was not any order in the state of nature. As a result, he puts forward that men had to cede some of their rights to create a state.
Subsequently, John Locke with his Second Treatise of Government (1690) shows similarities between state of nature and Golden Age, but for him it is not sufficient. People needed a state to protect them. Finally, Jean-Jacques Rousseau develops his own theory based on popular sovereignty. Indeed, he believes that citizens should write the laws together and abide to them. His theory is based on the notion of general will that implies the free subordination of citizens to the laws in order to be in peace. However, even if the term ‘natural right’ is widely used by eighteenth-century writers, their attempts to define it are rather weak. Just to use the example of the definition of ‘droit naturel’ by Diderot in the Encyclopédie, it is striking to see that the philosopher did not give any definition:
Le philosophe commence à sentir que de toutes les notions de la morale, celle du droit naturel est une des plus importantes et des plus difficiles à déterminer.
Since the beginning of the eighteenth-century, writers and philosophers had developed different versions of the same idea until the adoption of the term ‘rights of man’ in 1763. Considered as too general, the term ‘human rights’ was rarely used during the eighteenth-century. Nicolas Lenglet Du Fresnoy used the term ‘rights of humanity’ for the first time in 1734 in a satiric comment:
That is what happened to those good, those saints, those incomparable Monks of the sixth-century who renounced so well to all of the rights of humanity that they started to graze like animals.
As for the term ‘human rights’, it was used for the first time by Voltaire in 1763 in his Traité sur la tolérance, but was never really used by writers. The term that was actually adopted, ‘rights of man’ can be find for the first time in Rousseau’s Contrat Social and was already widely used in 1763.
 Jean-Jacques Rousseau, Du Contrat Social Ou Principes Du Droit Politique, 1762.
 Dan Edelstein, The Terror of Natural Right : Republicanism, the Cult of Nature, and the French Revolution (Chicago ; London: University of Chicago Press, 2009). P.11.
 Hugo Grotius (1583-1645) was a Dutch jurist and philosopher.
 Thomas Hobbes (1588-1679) was an English philosopher.
 John Locke (1632-1704) was an English philosopher and physician.
 Denis Diderot and Jean Le Rond d’Alembert, eds., Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers (Paris, 1751). Article ‘Natural right’ : ‘the philosopher starts to feel that among all the ideas of morality, the natural right is one of the most important and one of the most difficult to define.’
 Nicolas Lenglet Du Fresnoy (1674-1755) was a French scholar passionate by history, geography, philosophy and alchemy.
 Nicolas Lenglet Du Fresnoy, De L’usage Des Romans, Où L’on Fait Voir Leur Utilité et Leurs Différents Caractères : Avec Une Bibliothèque Des Romans Accompagnée de Remarques Critiques Sur Leur Choix et Leurs éditions (Amsterdam: Vve de Poilras, 1734). P.245: ‘C’est ce qui arrivait à ces bons, ces saints, ces inimitables Moines du VI. Siècle qui renonçaient si bien à tous les droits de l’humanité, qu’ils se mirent à paître comme les animaux.’
 Voltaire, Traité Sur La Tolérance, 1763. The term is used twice in the treatise: p.29, ‘the human right cannot be founded on anything else than the right of nature’ and p.30, ‘if it was of human right to behave like this, the Japanese would have to hate the Chinese, who would have executed the Siamese.’
 Jean-Jacques Rousseau, Du Contrat Social Ou Principes Du Droit Politique, 1762. The term is written once, p.109: ‘except the only nation that follows it [the religion], everything is for it unfaithful, foreign, barbaric; it only extends the duties and rights of man as far as its alters.’