Geneva-born thinker Jean-Jacques Rousseau's famous work of political philosophy from 1762 is based on a give-and-take theory of the relation between individual freedom and social order: the social contract that gives the work its name. Rousseau thinks about the issue by starting with what is known as the state of nature, a lawless condition where people are free to do what they like, governed only by their own instinctive sense of justice. People are free, but they are also vulnerable to chaos.

Issues of human rights and freedoms always inflame passions, and John Rawls's A Theory of Justice will do the same. Published in 1971, it links the idea of social justice to a basic sense of fairness that recognizes human rights and freedoms. Controversially, though, it also accepts differences in the distribution of goods and services - as long as they benefit the worst off in society.

First available in 1689, John Locke's Two Treatises of Government is considered one of the most important works ever written on the foundations of government. Published anonymously, it argues against the popular idea at the time that monarchs have a God-given right to rule. Instead Locke proposes that sovereignty - supreme authority - ultimately resides with the people.

In his 1807 work Phenomenology of Spirit, G. W. F. Hegel introduced the world to his philosophical system. His most influential work - and the culmination of the German Idealist movement begun in the late 18th century as a response to the works of Immanuel Kant - the book remains one of the undisputed classics of Western thought.

In his 1996 book The Clash Of Civilizations and the Remaking of World Order, American political scientist Samuel Huntington sets out his vision of the post-Cold War world. While the era from 1945 to 1989 was shaped by ideological conflict (communism vs. capitalism), Huntington predicts a future of cultural conflict.

When American sociologist C. Wright Mills's The Sociological Imagination was first published in 1959, it provoked much hostile reaction. This was understandable: the book was a hard-hitting attack on how sociology was practiced - and on a number of leading sociologists. Mills was a fierce critic of both modern capitalism and Soviet-style authoritarianism, and argued that the sociology profession failed to look at how people's problems are connected to the structures of the society in which they live.

English historian Christopher Hill turned thinking about the English Civil Wars (1642-51) on its head when he published The World Turned Upside Down in 1972. Instead of focusing on power struggles in the upper echelons of English society - on the battle between the monarchy and would-be republicans - Hill looked to develop "history from below", investigating the lives of ordinary people, the way they saw society, and their political hopes for the future.

Having witnessed some negative effects of democratic revolutions in his native France, Tocqueville visited America in 1831 to see what a functioning republic looked like. His main concerns were that democracy could make people too dependent on the state and that minority voices might not be heard - a problem he termed "The Tyranny of the Majority." By examining America thoroughly, Tocqueville hoped to show how a democratic system could avoid these pitfalls.

Defining liberty as freedom from interference by state power or popular moral opinion, Mill justifies the individual's right to this liberty by focusing on the role self-development plays in human well-being. His vision of individual rights extends to include freedom of thought and emotion and the freedom to act together with others. Society should protect the development of individuality to aid both social progress and innovation.

British-born American political activist Thomas Paine wrote Rights of Man in 1791 in response to Reflections on the Revolution in France, Edmund Burke's attack on the French Revolution. Burke was wary of tearing down old institutions of government. But Paine argued that revolution is acceptable - in fact, necessary - when government ignores the rights of its people. Not surprisingly, Rights of Man proved very popular in the newly liberated United States, selling over 100,000 copies.

An extraordinarily ambitious work, Republic has made important contributions to many branches of modern philosophy. The work unfolds as a series of conversations in which participants set out a number of different theories of justice, and then imagine how these theories might become reality within the political structure of a city. In examining justice, Plato investigates an enormous range of questions in the areas of ethics, politics, and even the nature of existence itself.

Though written around 1513, more than 500 years ago, Italian diplomat Niccolò Machiavelli's The Prince is still both widely listened to and very influential. Listeners turn to it for its direct advice on the question of how to attain - and retain - power. Machiavelli's answer, in brief: Use any means necessary to make sure the state survives.

Philosophy for busy people. Listen to this succinct account of the philosophy of Kant in just one hour. Immanuel Kant taught and wrote prolifically about physical geography yet never travelled farther than forty miles from his home in Königsberg. Appropriately, his philosophy strenuously denies that all knowledge is derived from experience, insisting instead that all experience must conform to knowledge. Kant’s aim was to restore metaphysics.

Philosophy for busy people. Listen to a succinct account of the philosophy of Hegel in just one hour. With Hegel philosophy became very difficult indeed – even the great man himself conceded that ‘only one man understands me, and even he does not.’ His dialectical method produced the most grandiose metaphysical system known to humanity, and included absolutely everything, its most vital element being the dialectic of the thesis, antithesis and synthesis.

In his 1983 book Nations and Nationalism, British-Czech intellectual Ernest Gellner put forward a theory of nationalism, explaining that the concept of nation is not in fact an ancient notion, as we might first imagine. Rather, it is a modern idea born out of the seismic social and cultural shifts that industrialization brought to the Western world.