The early Christian philosophy of Augustine of Hippo was heavily influenced by Plato. The main change that Christian thought brought was to moderate the Stoicism and theory of justice of the Roman world, and emphasize the role of the state in applying mercy as a moral example. Augustine also preached that one was not a member of his or her city, but was either a citizen of the City of God (Civitas Dei) or the City of Man (Civitas Terrena). Augustine's City of God is an influential work of this period that refuted the thesis, after the First Sack of Rome, that the Christian view could be realized on Earth at all - a view many Christian Romans held.
Saint Thomas Aquinas
In political philosophy, Aquinas is most meticulous when dealing with varieties of law. According to Aquinas, there are four different kinds of laws:
1) God's cosmic law
2) God's scriptural law
3) Natural law or rules of conduct universally applicable within reason
4) Human law or specific rules applicable to specific circumstances.
Mutazilite vs Asharite
The rise of Islam, based on both the Qur'an and Muhammad strongly altered the power balances and perceptions of origin of power in the Mediterranean region. Early Islamic philosophy emphasized an inexorable link between science and religion, and the process of ijtihad to find truth - in effect all philosophy was "political" as it had real implications for governance. This view was challenged by the "rationalist" Mutazilite philosophers, who held a more Hellenic view, reason above revelation, and as such are known to modern scholars as the first speculative theologians of Islam; they were supported by a secular aristocracy who sought freedom of action independent of the Caliphate. By the late ancient period, however, the "traditionalist" Asharite view of Islam had in general triumphed. According to the Asharites, reason must be subordinate to the Quran and the Sunna.
Islamic political philosophy, was, indeed, rooted in the very sources of Islam, i.e. the Qur'an and the Sunnah, the words and practices of Muhammad. However, in the Western thought, it is generally supposed that it was a specific area peculiar merely to the great philosophers of Islam: al-Kindi (Alkindus), al-Farabi (Abunaser), İbn Sina (Avicenna), Ibn Bajjah (Avempace), Ibn Rushd (Averroes), and Ibn Khaldun. The political conceptions of Islam such as kudrah (power), sultan, ummah, cemaa (obligation)-and even the "core" terms of the Qur'an, i.e. ibadah, din (religion), rab (master) and ilah- is taken as the basis of an analysis. Hence, not only the ideas of the Muslim political philosophers but also many other jurists and ulama posed political ideas and theories. For example, the ideas of the Khawarij in the very early years of Islamic history on Khilafa and Ummah, or that of Shia Islam on the concept of Imamah are considered proofs of political thought. The clashes between the Ehl-i Sunna and Shia in the 7th and 8th centuries had a genuine political character.
The 14th century Arab scholar Ibn Khaldun is considered one of the greatest political theorists. The British philosopher-anthropologist Ernest Gellner considered Ibn Khaldun's definition of government, "an institution which prevents injustice other than such as it commits itself", the best in the history of political theory. For Ibn Khaldun, government should be restrained to a minimum for as a necessary evil, it is the constraint of men by other men.
Medieval political philosophy in Europe was heavily influenced by Christian thinking. It had much in common with the Mutazalite Islamic thinking in that the Roman Catholics though subordinating philosophy to theology did not subject reason to revelation but in the case of contradictions, subordinated reason to faith as the Asharite of Islam. The Scholastics by combining the philosophy of Aristotle with the Christianity of St. Augustine emphasized the potential harmony inherent in reason and revelation. Perhaps the most influential political philosopher of medieval Europe was St. Thomas Aquinas who helped reintroduce Aristotle's works, which had only been preserved by the Muslims, along with the commentaries of Averroes. Aquinas's use of them set the agenda, for scholastic political philosophy dominated European thought for centuries even unto the Renaissance.
Medieval political philosophers, such as Aquinas in Summa Theologica, developed the idea that a king who is a tyrant is no king at all and could be overthrown.
Magna Carta, cornerstone of Anglo-American political liberty, explicitly proposes the right to revolt against the ruler for justice sake. Other documents similar to Magna Carta are found in other European countries such as Spain and Hungary.
During the Renaissance secular political philosophy began to emerge after about a century of theological political thought in Europe. While the Middle Ages did see secular politics in practice under the rule of the Holy Roman Empire, the academic field was wholly scholastic and therefore Christian in nature.
One of the most influential works during this burgeoning period was Niccolò Machiavelli's The Prince, written between 1511–12 and published in 1532, after Machiavelli's death. That work, as well as The Discourses, a rigorous analysis of the classical period, did much to influence modern political thought in the West. A minority (including Jean-Jacques Rousseau) could interpret The Prince as a satire meant to be given to the Medici after their recapture of Florence and their subsequent expulsion of Machiavelli from Florence. Though the work was written for the di Medici family in order to perhaps influence them to free him from exile, Machiavelli supported the Republic of Florence rather than the oligarchy of the di Medici family. At any rate, Machiavelli presents a pragmatic and somewhat consequentialist view of politics, whereby good and evil are mere means used to bring about an end, i.e. the secure and powerful state. Thomas Hobbes, well known for his theory of the social contract, goes on to expand this view at the start of the 17th century during the English Renaissance. Although neither Machiavelli nor Hobbes believed in the divine right of kings, they both believed in the inherent selfishness of the individual. It was necessarily this belief that led them to adopt a strong central power as the only means of preventing the disintegration of the social order.
John Locke in particular exemplified this new age of political theory with his work Two Treatises of Government. In it Locke proposes a state of nature theory that directly complements his conception of how political development occurs and how it can be founded through contractual obligation. Locke stood to refute Sir Robert Filmer's paternally founded political theory in favor of a natural system based on nature in a particular given system. The theory of the divine right of kings became a passing fancy, exposed to the type of ridicule with which John Locke treated it. Unlike Machiavelli and Hobbes but like Aquinas, Locke would accept Aristotle's dictum that man seeks to be happy in a state of social harmony as a social animal. Unlike Aquinas's preponderant view on the salvation of the soul from original sin, Locke believes man's mind comes into this world as tabula rasa. For Locke, knowledge is neither innate, revealed nor based on authority but subject to uncertainty tempered by reason, tolerance and moderation. According to Locke, an absolute ruler as proposed by Hobbes is unnecessary, for natural law is based on reason and seeking peace and survival for man.
European Age of Enlightenment
Eugène Delacroix's Liberty Leading the People (1830, Louvre), a painting created at a time where old and modern political philosophies came into violent conflict.
During the Enlightenment period, new theories about what the human was and is and about the definition of reality and the way it was perceived, along with the discovery of other societies in the Americas, and the changing needs of political societies (especially in the wake of the English Civil War, the American Revolution and the French Revolution) led to new questions and insights by such thinkers as Jean-Jacques Rousseau, Montesquieu and John Locke.
These theorists were driven by two basic questions: one, by what right or need do people form states; and two, what the best form for a state could be. These fundamental questions involved a conceptual distinction between the concepts of "state" and "government." It was decided that "state" would refer to a set of enduring institutions through which power would be distributed and its use justified. The term "government" would refer to a specific group of people who occupied the institutions of the state, and create the laws and ordinances by which the people, themselves included, would be bound. This conceptual distinction continues to operate in political science, although some political scientists, philosophers, historians and cultural anthropologists have argued that most political action in any given society occurs outside of its state, and that there are societies that are not organized into states which nevertheless must be considered in political terms. As long as the concept of natural order was not introduced, the social sciences could not evolve independently of theistic thinking. Since the cultural revolution of the 17th century in England, which spread to France and the rest of Europe, society has been considered subject to natural laws akin to the physical world.
Political and economic relations were drastically influenced by these theories as the concept of the guild was subordinated to the theory of free trade, and Roman Catholic dominance of theology was increasingly challenged by Protestant churches subordinate to each nation-state, which also (in a fashion the Roman Catholic Church often decried angrily) preached in the vulgar or native language of each region. However, the enlightenment was an outright attack on religion, particularly Christianity. The publication of Denis Diderot's and Jean d'Alembert's Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers marked the crowning intellectual achievement of the epoch. The most outspoken critic of the church in France was François Marie Arouet de Voltaire, a representative figure of the enlightenment. After Voltaire, religion would never be the same again in France.
In the Ottoman Empire, these ideological reforms did not take place and these views did not integrate into common thought until much later. As well, there was no spread of this doctrine within the New World and the advanced civilizations of the Aztec, Maya, Inca, Mohican, Delaware, Huron and especially the Iroquois. The Iroquois philosophy in particular gave much to Christian thought of the time and in many cases actually inspired some of the institutions adopted in the United States: for example, Benjamin Franklin was a great admirer of some of the methods of the Iroquois Confederacy, and much of early American literature emphasized the political philosophy of the natives.
Industrialization and the Modern Era
Karl Marx and his theory of Communism developed along with Friedrich Engels proved to be one of the most influential political ideologies of the 20th century through Leninism.The industrial revolution produced a parallel revolution in political thought. Urbanization and capitalism greatly reshaped society. During this same period, the socialist movement began to form. In the mid-19th century, Marxism was developed, and socialism in general gained increasing popular support, mostly from the urban working class. Without breaking entirely from the past, Marx established the principles which would be used by the future revolutionaries of the 20th century namely Lenin, Mao Zedong, Ho Chi Minh and Fidel Castro. Although Hegel's philosophy of history is similar to Kant's, and Marx's theory of revolution towards the common good is partly based on Kant's view of history. Marx is said to have declared that on the whole, he was just trying to straighten out Hegel who was actually upside down. Unlike Marx who believed in historical materialism, Hegel believed in the Phenomenology of Spirit. Be that as it may, by the late 19th century, socialism and trade unions were established members of the political landscape. In addition, the various branches of anarchism, with thinkers such as Bakunin, Proudhon or Kropotkin, and syndicalism also gained some prominence. In the Anglo-American world, anti-imperialism and pluralism began gaining currency at the turn of the century.
World War I was a watershed event in human history. The Russian Revolution of 1917 (and similar, albeit less successful, revolutions in many other European countries) brought communism - and in particular the political theory of Leninism, but also on a smaller level Luxemburgism (gradually) - on the world stage. At the same time, social democratic parties won elections and formed governments for the first time, often as a result of the introduction of universal suffrage. However, a group of central European economists led by Austrians Ludwig von Mises and Friedrich Hayek identified the collectivist underpinnings to the various new socialist and fascist doctrines of government power as being different brands of political totalitarianism.
Contemporary political philosophy
From the end of World War II until 1971, when John Rawls published a Theory of Justice, political philosophy declined in the Anglo-American academic world, as analytic philosophers expressed skepticism about the possibility that normative judgments had cognitive content, and political science turned toward statistical methods and behavioralism. In continental Europe, on the other hand, the postwar decades saw a huge blossoming of political philosophy, with Marxism dominating the field. This was the time of Sartre and Althusser, and the victories of Mao Zedong in China and Fidel Castro in Cuba, as well as the events of May 1968 led to increased interest in revolutionary ideology, especially by the New Left. A number of continental European émigrés to Britain and the United States—including Hannah Arendt, Karl Popper, Friedrich Hayek, Leo Strauss, Isaiah Berlin, Eric Voegelin and Judith Shklar—encouraged continued study in political philosophy in the Anglo-American world, but in the 1950s and 60s they and their students remained at odds with the analytic establishment.
Communism remained an important focus especially during the 1950s and 60s. Colonialism and racism were important issues that arose. In general, there was a marked trend towards a pragmatic approach to political issues, rather than a philosophical one. Much academic debate regarded one or both of two pragmatic topics: how (or whether) to apply utilitarianism to problems of political policy, or how (or whether) to apply economic models (such as rational choice theory) to political issues. The rise of feminism, LGBT social movements and the end of colonial rule and of the political exclusion of such minorities as African Americans and sexual minorities in the developed world has led to feminist, postcolonial, and multicultural thought becoming significant.
In Anglo-American academic political philosophy the publication of John Rawls's A Theory of Justice in 1971 is considered a milestone. Rawls used a thought experiment, the original position, in which representative parties choose principles of justice for the basic structure of society from behind a veil of ignorance. Rawls also offered a criticism of utilitarian approaches to questions of political justice. Robert Nozick's 1974 book Anarchy, State, and Utopia, which won a National Book Award, responded to Rawls from a libertarian perspective and gained academic respectability for libertarian viewpoints.
Contemporaneously with the rise of analytic ethics in Anglo-American thought, in Europe several new lines of philosophy directed at critique of existing societies arose between the 1950s and 1980s. Most of these took elements of Marxist economic analysis, but combined them with a more cultural or ideological emphasis. Out of the Frankfurt School, thinkers like Herbert Marcuse, Theodor W. Adorno, Max Horkheimer, and Jürgen Habermas combined Marxian and Freudian perspectives. Along somewhat different lines, a number of other continental thinkers—still largely influenced by Marxism—put new emphases on structuralism and on a "return to Hegel". Within the (post-) structuralist line (though mostly not taking that label) are thinkers such as Gilles Deleuze, Michel Foucault, Claude Lefort, and Jean Baudrillard. The Situationists were more influenced by Hegel; Guy Debord, in particular, moved a Marxist analysis of commodity fetishism to the realm of consumption, and looked at the relation between consumerism and dominant ideology formation.
Another debate developed around the (distinct) criticisms of liberal political theory made by Michael Sandel and Charles Taylor. The liberal-communitarian debate is often considered valuable for generating a new set of philosophical problems, rather than a profound and illuminating clash of perspectives.
Charles Blattberg has offered an account which distinguishes between four different contemporary political philosophies: neutralism, postmodernism, pluralism, and patriotism.
There is fruitful interaction between political philosophers and international relations theorists. The rise of globalization has created the need for an international normative framework, and political theory has moved to fill the gap.