Enlightenment Political Philosophy: The Birth of Modern Government

The political thought of the Enlightenment is the most consequential body of political theory in the modern world. It provided the conceptual foundations for the American and French revolutions, the moral vocabulary of human rights, the institutional architecture of constitutional government, and the basic principles of liberal democracy. To read the political philosophers of the eighteenth century is to enter into a conversation that still shapes contemporary politics — though “conversation” is putting it generously. Much of what passes for contemporary political argument is, in fact, the eighteenth century talking past itself.

This article offers a comprehensive examination of Enlightenment political philosophy. It traces the central ideas — social contract theory, natural rights, the separation of powers, the general will, and the principles of republicanism and toleration — and shows how they were developed, contested, and eventually institutionalized in the revolutions and reforms of the late eighteenth century. The Cambridge school — Pocock, Skinner, and the older Cambridge tradition of intellectual history — has spent half a century arguing that this Enlightenment account misses the older republican tradition. They are right. They are also right that the republican tradition was largely eclipsed in the nineteenth century, and that what we now call “Enlightenment political philosophy” is the liberal tradition, in its late-eighteenth-century form.

The Background: From Divine Right to Natural Law

The political philosophy of the Enlightenment did not emerge in a vacuum. It was a response to the older doctrines of divine right and to the political crises of the seventeenth and eighteenth centuries.

The Decline of Divine Right

In the early modern period, European monarchs claimed to rule by divine right, with authority derived from God and mediated through the Church. The Protestant Reformation, which had begun in 1517, undermined the religious unity on which this theory depended, and the wars of religion that followed — culminating in the Thirty Years’ War of 1618 to 1648, which killed perhaps a third of the population of central Europe and reduced the population of Germany by similar proportions — demonstrated the catastrophic consequences of mixing political and religious authority.

The Peace of Westphalia (1648), which ended the Thirty Years’ War, established a new principle of religious coexistence. In the following century, a series of English revolutions — the Civil War, the execution of Charles I in 1649, the Glorious Revolution of 1688 — further undermined the claims of absolute monarchy. The English Bill of Rights (1689) and the Act of Toleration (1689) established a model of constitutional government that would inspire political thinkers across Europe. The English case was, for the rest of the eighteenth century, the model: a limited monarchy, a powerful Parliament, an established but not persecuting church, and a free press that was, in practice, a great deal freer than on the Continent. The fact that the English model was as much myth as reality is part of the story, not an exception to it.

The Natural Law Tradition

The natural-law tradition, going back to the Stoics and the medieval jurists, provided a vocabulary for thinking about politics that did not depend on either divine right or arbitrary will. The natural lawyers held that there were moral principles, accessible to human reason, that applied to all human beings. Different thinkers gave this basic idea very different content: Hugo Grotius (1583–1645) made it the basis of an international law that did not depend on religious unity; Thomas Hobbes (1588–1679) used it to justify absolute sovereignty; Samuel Pufendorf (1632–1694) and John Locke (1632–1704) used it to ground theories of limited government and individual rights.

The natural-law tradition was important to the Enlightenment in two ways. First, it provided a conceptual framework for thinking about politics that could be shared across religious and national lines. Second, it set the stage for the more ambitious political theories of the eighteenth century, which would attempt to ground political authority in a systematic account of human nature and human reason. The natural-law theorists are, in this sense, the bridge between medieval political thought and the modern: Hugo Grotius’s De jure belli ac pacis (1625) is the great transitional work, partly scholastic in its method, fully modern in its ambition.

The social contract was the central concept of Enlightenment political philosophy. The basic idea was that political authority was legitimate only to the extent that it rested on the agreement, express or tacit, of the governed. The idea is more interesting than it looks, because the contract theorists disagree on what the contract is. For Hobbes, the contract is a once-and-for-all act of submission to a sovereign. For Locke, the contract is a continuing trust that can be revoked when the trustee misbehaves. For Rousseau, the contract is an act of collective self-legislation in which each citizen, in a sense, contracts only with himself. The disputes among these readings are not academic; they are the source of modern political conflict.

Thomas Hobbes and the Foundations

The first major theorist of the social contract was Thomas Hobbes, in his Leviathan (1651). Hobbes argued that, in the absence of political authority, human life would be a “war of all against all” in which life was “solitary, poor, nasty, brutish, and short.” To escape this condition, people would consent, in a great act of collective decision, to transfer their natural rights to a sovereign authority whose commands they would obey.

Hobbes’s contract was authoritarian. The sovereign, once established, was not subject to the contract, and there was no right of resistance. Hobbes’s theory was, however, foundational for later contract theorists, all of whom had to engage with his argument that without a strong sovereign, political life was impossible. For a detailed account of Hobbes’s state of nature, see Hobbes’s State of Nature. Worth pausing on: the Leviathan was written during the English Civil War, and Hobbes’s commitment to absolute sovereignty was, in part, a response to the political chaos of the 1640s. He fled to Paris in 1640, returned to England in 1651, and submitted to the Cromwellian government. The politics, in other words, are the politics of a man who has seen what civil war looks like and who is willing to pay a high price for order. Whether the price is too high is, of course, the question the Enlightenment never quite answered.

John Locke’s Liberal Contract

John Locke, in his Two Treatises of Government (1689), rejected Hobbes’s absolutism. Locke argued that, in the state of nature, human beings were free and equal, and possessed natural rights to life, liberty, and property. They established political society, by contract, in order to protect these rights. Government was thus a kind of trust, and rulers who violated the trust could legitimately be resisted or overthrown.

Locke’s theory was decisive for the development of modern liberalism. It provided a systematic defense of revolution against tyranny, grounded in a natural-rights theory that did not depend on any particular religious commitment. The American revolutionaries, in particular, drew directly on Locke’s arguments. The Second Treatise was, in effect, the official ideology of the American Revolution, even if Jefferson’s drafting of the Declaration borrowed more from the natural-rights tradition than from Locke specifically. The political theology of the American founding is, in this sense, Lockean even when its authors claim to be doing something else.

Rousseau and the General Will

Jean-Jacques Rousseau, in his Social Contract (1762), gave the contract tradition a more radical and more democratic turn. Rousseau argued that legitimate political authority was not based on the protection of pre-political rights, but on the general will (volonté générale) — the will of the citizenry as a whole directed at the common good.

Rousseau’s general will was one of the most controversial ideas in the history of political thought. Some readers saw in it a noble conception of civic participation and democratic self-government. Others saw a dangerous doctrine that could be used to justify the suppression of individual dissent in the name of the collective. Robespierre and the Jacobins claimed Rousseau as an inspiration, and the tension between democratic and authoritarian readings of the general will has been a recurring theme of modern politics. The general will is, in fact, neither democratic nor authoritarian; it is a theoretical construction whose meaning depends on the institutional context in which it is applied. In Rousseau’s own small, frugal, intensely participatory republic, it has one meaning. In a modern mass democracy, it has another. The fact that twentieth-century totalitarians were able to claim Rousseau as a forerunner should be sobering; the fact that participatory democrats were also able to do so should be heartening. The text supports both readings, and the institutional choice — how to construct the institutions that will give the general will a real meaning — is the political choice.

Kant and the Cosmopolitan Order

Immanuel Kant, in his Perpetual Peace (1795) and other works, extended the contract tradition to the international order. Kant argued that just as individuals had a duty to leave the state of nature and enter civil society, so nations had a duty to leave the international state of nature and enter a federation of free republican states.

Kant’s cosmopolitanism had a profound influence on the development of international law and international institutions. The United Nations and the European Union are descendants of Kant’s project, though they are descendants he might not recognize. The Kantian project, taken seriously, requires a federation with the power to enforce its decisions on member states; the actual UN and the actual EU are weaker than that. Whether the world would be better or worse with a stronger Kantian federation is a question to which there is no theoretical answer, and probably no empirical one either.

Natural Rights and Human Rights

The language of natural rights was one of the most powerful legacies of the Enlightenment. Although the idea of natural rights can be traced back to antiquity, it was the seventeenth- and eighteenth-century political philosophers who gave the concept its modern form. The historical scholarship on the concept is extensive and contentious. Richard Tuck’s work has traced the early modern origins to the Spanish scholastics; the Cambridge school has emphasized the republican tradition; Michael Sonenscher has argued that the key is the eighteenth-century debates about property and subsistence. Each reading has merit, and each misses something the others see. The simple fact is that the modern doctrine of natural rights is not the work of any one thinker, and the attempt to locate its origin in a single text is a mistake.

The Theory of Natural Rights

The natural-rights theorists argued that human beings, by virtue of their nature, possessed certain rights that could not legitimately be violated by any government. These rights were variously enumerated, but the most influential list was that of Locke: life, liberty, and property.

The natural-rights theory had several distinctive features. First, the rights were held by individuals, not by groups or communities. Second, the rights were universal — they applied to all human beings, regardless of their nationality, religion, or social position. Third, the rights were “inalienable” — they could not legitimately be surrendered or transferred to another.

These features made the natural-rights theory a powerful instrument of political criticism. Whatever particular institutions or practices might be defended on grounds of tradition or necessity, the natural-rights theory provided a standing test of their justice. That is the great strength of the doctrine. It is also, as the conservative critics from Burke to Oakeshott have pointed out, the source of its weakness. A standing test of justice is also a permanent invitation to revolution; a universal claim of right is also a universal claim to overturn whatever is. The fact that natural-rights theory has been used both to abolish slavery and to justify the execution of kings, both to extend the franchise and to terrorize the unfranchised, suggests that the doctrine is, in itself, indeterminate. The political content comes from the political use.

The American and French Declarations

The American Declaration of Independence (1776) and the French Declaration of the Rights of Man and of the Citizen (1789) translated the natural-rights theory into constitutional form. The American Declaration, drafted primarily by Thomas Jefferson, held that “all men are created equal” and “endowed by their Creator with certain unalienable Rights.” The French Declaration, drafted by a committee of the National Constituent Assembly that included Lafayette, Sieyès, Mounier, and others, and informed by Jefferson (who was, as American minister to France, in regular conversation with the drafters), articulated a similar list of rights, including liberty, property, security, and resistance to oppression.

These declarations were not merely philosophical statements. They were political acts, intended to justify the new governments being established in the American colonies and in revolutionary France. The political effectiveness of the rights language was one of the great lessons of the late eighteenth century. The lesson, in turn, is one of the great lessons of the twentieth century. The Universal Declaration of Human Rights (1948) is, in its textual form, a direct descendant of the American and French declarations, and it is the founding text of a regime that has had more real-world political effect than any of its eighteenth-century predecessors. The same language has been used to abolish torture in Argentina, to organize dissident movements in Eastern Europe, to defend indigenous land rights in Canada, and to condemn apartheid in South Africa. The language is real. The politics is real. The connection between them is contested, and will continue to be contested.

The Universal Declaration of Human Rights

The natural-rights tradition of the Enlightenment was the immediate ancestor of the modern international human rights regime. The United Nations Universal Declaration of Human Rights (1948), drafted in the aftermath of the Second World War by a committee chaired by Eleanor Roosevelt, was an attempt to translate the eighteenth-century commitment to natural rights into a global moral and legal framework. Roosevelt was a determined and skillful chair; René Cassin did much of the actual drafting; the Chinese representative, Peng Chun Chang, contributed a Confucian theory of human rights that the Western members had not considered; Charles Malik, the Lebanese philosopher, brought the natural-law tradition; the Soviet representatives, led by Andrei Vyshinsky, insisted on the inclusion of economic and social rights. The result was a document that was both more and less than an Enlightenment declaration: more, in the sense that it covered a wider range of rights; less, in the sense that it was an instrument of cold war politics as well as a statement of principle.

The Declaration drew directly on the language and the structure of the eighteenth-century declarations. It listed a wide range of civil, political, economic, social, and cultural rights, and it affirmed the principle that these rights applied to all human beings, regardless of nationality, race, religion, or sex. The right to property was, in the final draft, treated as a matter of national legislation rather than as a universal right — a compromise that reflected the Soviet position. The debate over whether economic and social rights are “real” rights, or merely aspirational declarations, is in some sense the same debate the eighteenth century had about the right to subsistence, and has not been resolved.

The Separation of Powers

The doctrine of the separation of powers was one of the most influential practical contributions of Enlightenment political philosophy. The basic idea was that political power should be divided among different branches of government, each of which would check the others, in order to prevent the concentration of authority in any one person or group. The doctrine, in its mature form, is more sophisticated than the simple tripartite scheme suggests; the actual US Constitution provides for a much more elaborate system of checks and balances than the textbook version of the doctrine.

Montesquieu’s Theory

Montesquieu, in The Spirit of the Laws (1748), developed the most influential version of the doctrine. Drawing on his reading of the English constitution, Montesquieu distinguished among the legislative, executive, and judicial functions of government and argued that each should be exercised by a distinct body. He famously argued that “there can be no liberty where the legislative and executive powers are united in the same person, or in the same body of magistrates.” The famous chapter, Book XI, chapter 6, has done more constitutional work than almost any other paragraph in the history of political theory.

Montesquieu’s theory was not a simple call for the separation of powers in any abstract sense. He was concerned to identify the specific institutional arrangements that would prevent the abuse of power, and he was sensitive to the dangers both of concentration and of fragmentation. The English constitution he described, with its mixture of monarchy, aristocracy, and democracy, was for him the most successful modern example, though in fact it was not strictly a separation of powers in the American sense; the king sat in Parliament, and the House of Lords performed both legislative and judicial functions.

The American Constitution

The American Constitution of 1787, drafted at the Philadelphia Convention, gave the separation of powers its most successful practical expression. The Constitution established a Congress with legislative power, a President with executive power, and a Supreme Court with judicial power, and it provided for a complex system of checks and balances among the three branches. The federal judiciary, with its power of judicial review (formally established in Marbury v. Madison in 1803, twelve years after the Constitution was ratified), is the most distinctive American contribution to the doctrine.

James Madison, in The Federalist (1787–1788), provided the most systematic theoretical defense of the American system. Madison argued that the separation of powers was necessary to control the “violence of faction” and to protect the rights of minorities. The American system has endured, in broad outlines, to the present day. Notice that Madison’s “violence of faction” argument is, in fact, more of an argument for the extended republic and for the multiplication of interests than it is for the separation of powers in the strict sense. The Federalist is, on close reading, a much more sophisticated document than the textbook treatment of it suggests; Madison was not a Montesquieuian, and his reasons for the elaborate constitutional scheme were partly his own.

The Spread of Constitutionalism

The American example inspired constitutional movements across Europe and Latin America in the nineteenth century. The French revolutionary constitutions of 1791 and 1793, the Spanish Constitution of 1812, the Norwegian Constitution of 1814, and many others were influenced by the American model. The contemporary phenomenon of constitutional review, in which courts assess the constitutionality of legislation, is a direct descendant of the Enlightenment project of limited government. Whether constitutional review is, on the whole, a good idea is, of course, a question that divides the heirs of the Enlightenment. The early Madisonians were skeptical of judicial review; Jefferson, after his election, was openly hostile to it. The fact that the doctrine has become a basic feature of modern constitutional government is a result of historical accident and political struggle, not of a consensus among the founders.

Republicanism and Liberalism

The political philosophy of the Enlightenment gave rise to two great traditions: republicanism and liberalism. The two traditions were not always distinct, and the boundaries between them were often blurred, but they had different emphases and different political implications. The Cambridge school, beginning with J. G. A. Pocock’s Machiavellian Moment (1975), has argued that the republican tradition is older, more distinct, and more important than the standard liberal histories of political thought allow. They are, on this, broadly right; the price of their argument has been a tendency to minimize the genuine differences between the two traditions and the genuine influence of the liberal one.

The Republican Tradition

The republican tradition emphasized civic virtue, the common good, and active participation in self-government. Drawing on the example of the Roman Republic and the Italian city-republics of the Renaissance, the republicans held that liberty required not only the protection of individual rights but also the active involvement of citizens in the life of the polis.

Rousseau was the great theorist of this tradition. His Social Contract imagined a small, frugal, and intensely participatory republic, in which citizens would assemble to decide the laws under which they would live. The American revolutionaries, especially in the smaller states of New England, also drew on republican ideas. The town meeting, in New England, was a republican institution; the large commercial republic that the United States became was a different kind of thing, and the tension between the two has been a permanent feature of American political life.

The republican tradition has had a long afterlife. The civic-republican strand of contemporary political thought, associated with writers such as Hannah Arendt, J.G.A. Pocock, and Quentin Skinner, has emphasized the importance of civic participation and the dangers of excessive individualism. Whether the republican tradition can be revived in a mass democracy, where the conditions of the small city-state cannot be reproduced, is a question the civic-republicans have not fully answered.

The Liberal Tradition

The liberal tradition, examined in detail in Republicanism and Liberalism, emphasized individual rights, limited government, and the protection of personal liberty. Drawing on Locke and the Scottish Enlightenment, the liberals held that the proper function of government was to protect the rights and interests of individuals, and that government should be constitutionally limited in its powers.

The American Constitution, with its Bill of Rights, was the most successful practical expression of the liberal tradition. The economic liberalism of Adam Smith and his successors, with its emphasis on free markets and the limited role of the state, was another important expression. The liberal tradition has been the dominant political philosophy of the modern West, and its critics have argued, with some justice, that it tends to promote excessive individualism, neglect the common good, and tolerate or even encourage social inequality. The contemporary debate between liberals and their critics continues to be one of the central features of modern political life, and the terms in which it is conducted are still recognizably the terms of the eighteenth century.

Revolution and Reform

The political philosophy of the Enlightenment was intimately connected to the great political events of the late eighteenth century. The American Revolution of 1776, the French Revolution of 1789, the Haitian Revolution of 1791–1804, and the long sequence of revolutions and reforms that followed all drew on Enlightenment ideas. The relation between ideas and events is, of course, complicated. Ideas do not cause events; events do not derive from ideas. But in the late eighteenth century, the connection is unusually direct: the Declaration of Independence (1776) reads like a restatement of Locke’s Second Treatise; the French Déclaration des droits de l’homme (1789) reads like a synthesis of Locke, Rousseau, and the Encyclopédie; Toussaint Louverture wrote pamphlets in the 1790s that quoted Rousseau. The ideas were, in these cases, doing real political work.

The American Revolution

The American Revolution was the first great political event of the Enlightenment. It was a moderate revolution, conducted by a propertied elite in the name of universal rights. The Declaration of Independence, with its appeal to natural rights, was a manifesto of Enlightenment political philosophy.

The American Constitution, ratified in 1788, established a system of government that has endured to the present day. The Bill of Rights, added in 1791, provided a catalogue of individual rights that became a model for constitutional democracies around the world. The American case is, in many respects, the easy case: a small, prosperous, relatively homogeneous population, no entrenched aristocracy, no established church, no colonial rival on its territory. The American Constitution succeeded, in part, because the conditions for it were unusually favorable. The harder case is what to do in places where the conditions are less favorable, and the harder case is the one most of the modern world has had to face.

The French Revolution

The French Revolution was more radical and more violent than the American. It abolished feudalism, confiscated church property, executed the king, and experimented with new republican forms. The Declaration of the Rights of Man and of the Citizen became a manifesto of universal human rights.

The Revolution went through several phases. The moderate constitutional monarchy of 1789–1792 gave way to the radical republic of 1792–1795, the Directory of 1795–1799, and finally the Consulate and Empire of Napoleon Bonaparte. Throughout these phases, the rhetoric of Enlightenment political philosophy continued to be deployed, although the practical results were often very different from the original ideals. The Terror of 1793–1794 is the great test case for what happens when the political vocabulary of the Enlightenment is taken over by people with absolute power. The philosophes, mostly, would have been horrified. The philosophes, also, were not in a position to prevent it.

The Conservative Response

The French Revolution provoked a powerful conservative response. Edmund Burke’s Reflections on the Revolution in France (1790) attacked the abstract universalism of the revolutionaries and defended a politics rooted in tradition, custom, and prescription. The book is a sustained polemic against the revolutionaries’ “abstract” principles — liberty, equality, rights — which Burke argued were dangerous when detached from the concrete institutions and practices of a particular community. Joseph de Maistre (1753–1821) developed a systematic counter-revolutionary political philosophy. The German Romantic reaction against the Enlightenment, in thinkers such as Herder, Schlegel, and the early Hegel, was in part a response to the perceived excesses of the French Revolution.

The conservative response was not simply a refusal of Enlightenment values. Burke, in particular, was a serious political thinker who combined a defense of tradition with a sophisticated appreciation of the role of prejudice (in the original sense of pre-judgment) in social life. The conservative tradition has been an enduring feature of modern political thought, and the cheap dismissal of Burke as a mere reactionary is one of the laziest habits of contemporary political argument. The debate between Burke and the philosophes is not over, and the fact that it is not over is one of the more healthy signs of contemporary political thought.

Toleration, Pluralism, and the Modern State

One of the great achievements of Enlightenment political philosophy was the development of a theoretical foundation for religious toleration and political pluralism. The wars of religion, culminating in the Thirty Years’ War, had demonstrated the dangers of religious uniformity, and the philosophers of the Enlightenment developed arguments for a politics that could accommodate deep disagreement. The argument was, in the period, hard-won. Toleration was not a natural extension of Enlightenment principles; it was a long, contested political achievement, won against the resistance of both churches and states.

Locke’s Theory of Toleration

Locke’s Letter Concerning Toleration (1689) was one of the foundational texts of the modern theory of religious freedom. Locke argued that the state had no authority to use force in matters of religious belief, and that the church was a voluntary association of believers with no right to coerce its members or non-members. The argument was revolutionary for its time. It is also, in retrospect, the foundation of a much larger structure of religious freedom that Locke himself would not have endorsed.

Locke’s theory was not without limits. He excluded Catholics and atheists from the scope of toleration, on the grounds that Catholics owed allegiance to a foreign power and atheists could not be trusted to keep their promises. The exclusions are not incidental. They are an attempt to draw the line between religious beliefs that can be tolerated and those that cannot, and the line is drawn on grounds that the eighteenth century could defend but that the modern period cannot. The basic principle of religious freedom was established, however, and later thinkers extended it to all groups. The work of extension is, of course, the work of the long nineteenth and twentieth centuries, and the fact that it is still going on is one of the more encouraging signs of contemporary politics.

Voltaire and the Defense of Toleration

Voltaire made religious toleration one of his great causes. His Treatise on Tolerance (1763) was written in response to the case of Jean Calas, a Protestant merchant in Toulouse who had been falsely accused of murdering his son and executed under torture in 1762. The Calas affair is one of the great cases of Enlightenment political campaigning. Voltaire did not just write a treatise; he spent three years mobilizing public opinion, in France and across Europe, against the Toulouse parlement. The campaign worked; Calas was posthumously exonerated in 1765. The campaign also made the cause of toleration a popular cause in France, in a way that no abstract philosophical argument could have done.

Voltaire’s work was widely read and helped turn the cause of toleration into a central cause of the Enlightenment. The idea that religious differences should not be settled by force became a fundamental principle of the modern liberal state. The principle, of course, is not the practice. The history of religious violence after the Enlightenment is, in many places, the history of its violation. The principle is what matters, and the principle is the inheritance.

Pluralism and the Limits of Toleration

The Enlightenment theory of toleration was not without its limits. It was developed in a context in which the boundaries of toleration were drawn primarily along religious lines, and the application of the principle to other groups — racial, ethnic, sexual, or ideological — was a long and contested process. The work of extending toleration, from the seventeenth century to the present, is a long and unfinished work, and the unfinished quality is part of the point. The principle of toleration is, in the strict sense, self-limiting: it does not tell us how to draw the boundaries of the community that is to tolerate; it only tells us that there must be a community that tolerates.

The contemporary world has inherited the Enlightenment principle of toleration while also extending it to a wider range of differences. The challenges of contemporary pluralism — including the accommodation of cultural, religious, and ideological diversity in a single political community — are the inheritors of the Enlightenment project. The fact that they are still being worked out is the sign of a tradition that is still alive.

Conclusion

The political philosophy of the Enlightenment was one of the great intellectual achievements of human history. It produced a vocabulary of natural rights, a theory of legitimate government, a set of institutional principles for limiting power, and a commitment to religious toleration and human dignity that have become the moral foundation of the modern world. The political heirs of the Enlightenment include both the defenders and the critics of the modern liberal state. The American Constitution, the European Convention on Human Rights, the United Nations Charter, and the Universal Declaration of Human Rights are all descendants of the political philosophy developed by the thinkers of the eighteenth century. So too, in a more complicated way, are the critiques of that philosophy developed by the Romantics, the conservatives, the Marxists, the feminists, and the postcolonial thinkers.

To engage seriously with the political philosophy of the Enlightenment is to engage with the political life of our own time. The arguments of the eighteenth century remain alive in the institutions, the legal systems, and the political debates of the twenty-first. The work of building a just and free political order — the work that the Enlightenment began — remains unfinished, and the recognition that it is unfinished is, perhaps, the most useful inheritance of all.