Thomas Hobbes 1588-1679
Thomas Hobbes in some older texts Thomas Hobbs of Malmsbury, was an English philosopher, best known today for his work on political philosophy. His 1651 book Leviathan established the foundation for most of Western political philosophy from the perspective of social contract theory. He was one of the founders of modern political philosophy. His understanding of humans as being matter and motion, obeying the same physical laws as other matter and motion, remains influential; and his account of human nature as self-interested cooperation, and of political communities as being based upon a "social contract" remains one of the major topics of political philosophy. In addition to political philosophy, Hobbes also contributed to a diverse array of other fields, including history, geometry, the physics of gases, theology, ethics, and general philosophy. Here is a link on Hobbes.
John Locke 1632- 1704
John Locke is widely known as the Father of Classical Liberalism, was an English philosopher and physician regarded as one of the most influential of Enlightenment thinkers. Considered one of the first of the British empiricists, following the tradition of Francis Bacon, he is equally important to social contract theory. His work had a great impact upon the development of epistemology and political philosophy. His writings influenced Voltaire and Rousseau, many Scottish Enlightenment thinkers, as well as the American revolutionaries. His contributions to classical republicanism and liberal theory are reflected in the United States Declaration of Independence. Locke's theory of mind is often cited as the origin of modern conceptions of identity and the self, figuring prominently in the work of later philosophers such as Hume, Rousseau and Kant. Locke was the first to define the self through a continuity of consciousness. He postulated that the mind was a blank slate or tabula rasa. Contrary to pre-existing Cartesian philosophy, he maintained that we are born without innate ideas, and that knowledge is instead determined only by experience derived from sense perception. Here is more information on Locke.
Montesquieu 1689-1755
Montesquieu was a French social commentator and political thinker who lived during the Age of Enlightenment. He is famous for his articulation of the theory of separation of powers, which is taken for granted in modern discussions of government and implemented in many constitutions throughout the world. He was largely responsible for the popularization of the terms feudalism and Byzantine Empire. Here is more information on Montesquieu.
Jean-Jacques Rousseau 1712- 1778
Jean-Jacques Rousseau was a Genevan philosopher, writer, and composer of 18th-century Romanticism of French expression. His political philosophy influenced the French Revolution as well as the overall development of modern political, sociological, and educational thought. Rousseau's novel Emile or, On Education is a treatise on the education of the whole person for citizenship. His sentimental novel Julie, or the New Heloise was of importance to the development of pre-romanticism and romanticism in fiction. Rousseau's autobiographical writings his Confessions, which initiated the modern autobiography and his Reveries of a Solitary Walker, exemplified the late 18th-century movement known as the Age of Sensibility, and featured an increased focus on subjectivity and introspection that later characterized modern writing. His Discourse on the Origin of Inequality and his On the Social Contract are cornerstones in modern political and social thought. Rousseau was a successful composer of music, who wrote seven operas as well as music in other forms, and made contributions to music as a theorist. During the period of the French Revolution, Rousseau was the most popular of the philosophers among members of the Jacobin Club. Rousseau was interred as a national hero in the Pantheon in Paris, in 1794, 16 years after his death.