John Locke's Second Treatise of Government (1690) is one of the most important works in the history of Western political thought. Perhaps with only such exceptions as Aristotle's Politics, Machiavelli's The Prince, and Marx's Communist Manifesto, no other political treatise has had as great an influence on political thinking and political events both at the time of its publication and in the centuries that followed. The central principles of what today is broadly known as political liberalism - individual liberty, the rule of law, government by consent of the people, and the right to private property - were made current in large part by Locke's Second Treatise. These principles are today quite familiar and, indeed, are now taken for granted as fundamental to the human condition. Most liberal theorists writing today, whether explicitly or implicitly, look back to Locke as the source of their ideas. But even those who most forcefully object to his description of political life invariably respond to his formulation of these ideas. Some maintain that religious fundamentalism, "post-modernism," and socialism are today the only remaining ideological threats to liberalism. To the extent that this is true, these ideologies are ultimately attacks on the ideas that Locke, arguably more than any other, helped to make the universal vocabulary of political discourse.

Born in 1632 in Somerset, England, Locke was the son of an attorney in a middle-class family. In 1652 he went to Oxford, originally intending to be ordained in the church. Only later did he decide against this course, undertake studies to become a doctor of medicine, and eventually turn topolitics and philosophy. Although Locke's pursuit of the medical degree was cut short by academic politics at Oxford, he did learn enough to begin practicing as a doctor, and it was while working in this capacity that he first met Anthony Ashley Cooper, later the first earl of Shaftesbury, who was one of the most prominent political figures of the day. The two became friends, and Locke went to live with the Ashley family, serving as Lord Ashley's personal physician and later as tutor to his grandson, the third earl of Shaftesbury. The first earl introduced Locke to the world of politics; early in their association, Locke served as secretary of the Board of Trade and Plantations and secretary to the Lords Proprietors of the Carolinas. In 1696, Locke was made Commissioner of Trade, a position he held for several years before his death in 1704.

For all of his successes, however, Locke's political career might be thought to have developed in spite of himself. It was only through his association with Shaftesbury, and perhaps under his influence, that Locke was drawn into the political whirlwind of the time. When he began writing the Second Treatise (now thought to be around 1679 or 1680), the English monarchy had been restored for only twenty years but was already beginning to breed the very same conditions that precipitated the civil war of the 1640s, which had resulted in the execution of Charles I in 1649. During the 1680s, a political movement arose, the primary rationale for which was opposition to the policies and practices of Charles II and later of James II, who were attempting to assert absolute political authority over the people and, more important, over Parliament, just as Charles I had done forty years before. This movement was instrumental in precipitating the bloodless coup d'etat known as the Glorious Revolution (1688-89) in which James II was removed from the throne and replaced by his cousins, William and Mary. Shaftesbury was one of the leaders of this movement, and Locke almost unavoidably became a participant in the revolution as well. Locke's primary function was as an intellectual. It is likely that he intended the Two Treatises of Government as a manifesto providing the theoretical basis for opposing Charles II and outlining the movement's program for political change. He wrote the bulk of the treatises in the years before the coup had been effected, probably in France or Holland where Locke, fearing that he might be arrested or perhaps even executed for his participation in anti-government activity, went into exile. Because the Two Treatises were published (anonymously) in 1690 after the revolution had already taken place, they were until very recently considered a post facto justification for the revolution. It would be more accurate, however, to think of the Second Treatise in particular as a document comparable to Karl Marx's Communist Manifesto or the Declaration of Independence, and to consider John Locke (given his direct political involvement in the regime change) as a revolutionary figure of the stature of Lenin or Jefferson.

If Locke's political career can be seen as somewhat reluctant, the same cannot be said of his literary career. Although he published little until later in his life (and much of that anonymously), he began writing at a young age, shortly after he entered Oxford. His primary interests at this time focused on questions of religion and natural law, and he wrote some early essays (in Latin and left unpublished) on the latter subject. Although these essays have something of a morally conservative tone, Locke would later give the law of nature a central place in his argument in the Second Treatise. His religious views and his view of the Christian church in particular can be seen most clearly in The Reasonableness of Christianity (1695), the Discourse on Miracles (published posthumously in 1706), and various essays on the letters of Paul. His ideas about the relation between the authority of the state and the institutions of organized religion resulted in several letters on the subject of toleration. Locke's early political work includes the Two Tracts on Government (1660-61, left unpublished), which reflects a view of government more conservative and authoritarian than he would advocate in the Second Treatise. He also wrote the Constitution of the Carolinas (in collaboration with Shaftesbury), which provided a constitutional framework for the territory in the English colonies that would later become North and South Carolina. This constitution is especially interesting when read in the context of the Second Treatise, since it provides an account of how Locke may have envisioned his theory to play out in practice. Beyond his political writings, among Locke's most influential work are his philosophical treatises, An Essay Concerning Human Understanding (1689) and Of the Conduct of the Understanding (published posthumously in 1706); and a lesser-known treatise on education, Some Thoughts Concerning Education (1693). Though not widely read today, the Education was quite popular at the time, going through several editions and even being translated into French. Again, it is difficult to overstate the importance of this work, which introduced what today is known as "child-centered" education, eschewing the traditional view that children should be seen and not heard; it influenced such later educational theorists as Dewey, Montessori, and Piaget. The Essay and the Conduct are a central part of Western philosophical tradition. Locke's Essay is an example of empiricist philosophy, which argues that all knowledge is derived through the senses by observation of the external world. It is frequently placed in opposition to Cartesian rationalism, which suggests that some knowledge is innate or constructed in isolation from experience. The aspect of empiricism that stresses the role of experience in knowledge is the basis for the modern scientific method, and Locke developed his views while a member of the Royal Society, a group of prominent scientists including, among others, Robert Boyle. The description of the "state of nature" in the Second Treatise is suggestive of the empiricist method articulated in the Essay; and the lengthy and abstract discussion of liberty in the Essay underlies the parallel discussion in the Second Treatise. In spite of such clear connections, however, with one exception in the Education, none of these works makes reference to any other. This would be unremarkable if it were not for the fact that the Essay and the Education were conceived and written at approximately the same time as the Second Treatise, and they are all directly and fundamentally related to each other. For this reason, one should not make the mistake of reading the Second Treatise in isolation. A full understanding of this work is only possible when it is read with reference, surely to the Letter on Toleration and the Education, but most importantly to the Essay, which lays the philosophical foundation to Locke's political liberalism.

The variety of Locke's interests and the breadth of his knowledge are remarkable. It is true, however, that many of his ideas were derived from earlier theorists. For example, others had already written extensively on the subjects that Locke addressed in the Second Treatise. Hugo Grotius, a Dutch theorist, is thought to be the originator of the social contract theory of the state, which maintains that political society only legitimately arises when individuals come together and form a "compact" whereby they agree to establish a government and give it the rightful authority to make laws for them. This theory is grounded on the principles of individual liberty and popular consent, two ideas that were central to Locke's argument. Grotius had also written in his greatest work, On the Law of War and Peace (1625), about two other fundamental principles in Locke's political system: natural law and private property. Like Grotius, Thomas Hobbes, writing in the context of the English civil war, had described in the Leviathan (1651) the "state of nature" and the perfect liberty and equality of individuals in that state. He too argued that government is derived from a social compact.

Thus, the language of liberalism that Locke utilized was already part of the political discourse when he first began to think and write about politics. Locke's contribution then is not so much that he introduced the world to this language as that he popularized it and made it more palatable and more compelling to the ruling intellectual and political elite. Indeed, he contributed to the development of the belief that a liberal constitutional monarchy might even be more politically expedient than the absolutism of the past to maintain social stability and secure the position of the elite. It is above all for this reason that Locke should be thought of as the father of political liberalism, because he was, rhetorically, a more effective advocate of liberal ideas than his predecessors.

But what precisely makes Locke's Second Treatise so much more compelling than the work of earlier writers? To take Locke's greatest and most notorious rival, Hobbes begins his Leviathan with the assumption that individuals are naturally at liberty and the establishment of government is based in the consent of the people. Hobbes concludes, however, by advocating a form of absolute monarchy. Since he presupposes that individuals are for the most part self-interested and rapacious, Hobbes believes that political order is only possible if the king is given almost unlimited power. In the period following the restoration when there were widespread worries about the king's power in relation to Parliament, this Hobbesian view came to be discredited. Locke was quite careful to distance himself from that view, only referring to Hobbes obliquely and substantially modifying both the description of individuals in the state of nature and the kind of regime that followed from that description. Locke maintained that, although individuals are fundamentally self-interested, they are not as violent and dangerous as Hobbes assumed. Given a more docile population, an oppressive government is not necessary to avoid anarchy. In fact, as the American federalists were to understand a century later, although there may be a danger in giving too much liberty to the people, there is likely to be a greater danger in giving too much power to the government. Locke's insight was that Hobbesian absolutism is far more prone to political chaos than is a system of limited, albeit efficient, government. His prescription for reducing the potential for an abuse of power by the government was to establish a rudimentary form of checks and balances between king and Parliament, with the legislative body given a greater share of power than the executive, but with each office limited by the enumeration of its exact functions. Locke does not provide any great detail about the specifics of this system, and his ideas were later much refined and elaborated by others in the following century, but the basic outline for constitutional government is already present in, and is one of the central features of, the Second Treatise.

At the foundation of this constitutionalism is Locke's theory of individual right and natural law, and his argument that popular consent is the prerequisite for any legitimate government. Locke begins with the assumption that individuals are naturally in a state of liberty and equality, in the sense that no individual has any rightful authority over any other. However, if everyone is perfectly free to do anything at all, there would be chaos. Thus there must be some limitation on what people can legitimately do. This limitation is provided for by the law of nature, which stipulates that every individual must, wherever possible, seek to protect the life and liberty of everyone else. However, since individuals are basically self-interested, and since they are prone to abuse their liberty, what will induce them to obey this law? One of Locke's innovations in natural law theory is that he ties the law of nature directly to an individual's self-interest. He suggests that an individual is far more likely to limit his own freedom, and to protect the life and liberty of others, if he believes that his own life and liberty are better served by doing so. Indeed, it is this belief that leads to the idea of establishing political society. Government, though it limits the freedom of each individual, ultimately secures that freedom by protecting the interests of all. The desire to introduce a political association is thus the paradigm example of the natural law at work, uniting self-interest with public interest. In Locke's view, consent is the basis for political society, not only in the familiar sense that government cannot be legitimate where it has not been properly authorized, but more important in the sense that political association is not even possible under conditions in which individuals do not in some significant way identify their own interest with the interests of others.

The prescription for constitutional government and the discussion of natural law and consent might not in themselves be sufficient to differentiate Locke from his predecessors. One of the elements that made Locke's system particularly appealing was the way it justified locating power primarily in Parliament rather than in the king. Parliament was, of course, a representative body, but the interests it represented were predominantly, if not solely, those of the propertied classes. The Second Treatise makes quite clear that the protection of these interests is the fundamental purpose of government. One of the principal grievances against Charles II and James II was that they did not respect the private property of citizens. The Second Treatise, therefore, makes central the right to property (broadly understood as life, liberty and estate, but nonetheless "property"), and Locke states repeatedly that the function of government is the protection of this right. His implicit suggestion is that a truly limited government requires that there be a center of power independent of the king. Only by securing the right to property can monarchic power be balanced by the power of the propertied members of society. In order to solidify this balance, Locke made the property right "natural," and therefore inalienable, thereby modifying the positions of Grotius and Hobbes, who considered the right to property something that was established and regulated by government. Locke argued that the unequal distribution of property also occurs naturally and is agreed to prior to the establishment of political society. Thus the government's primary function of protecting property has the consequence of preserving these differences in wealth. According to Locke, shielding wealth increased the stability and general welfare of the entire community. This aspect of the Second Treatise is the antecedent of the economic theories of Adam Smith, Friedrich Hayek, and Milton Friedman.

However, Locke did not ignore those without property. He paid heed, as Hobbes and the others did not, to the fundamental principle of the individual liberty of all by stressing the ultimate sovereignty of the people, their right to establish the form of government and, in case of the abuse of power, their right to revolution. Although Locke qualifies his statements in this regard, and though he is not as unambiguous about how popular sovereignty works in practice as he is about private property, he lays the groundwork for a government "of the people, by the people, and for the people." In fact, to the extent that "property" refers to life and liberty (and not merely to estate), Locke indicates that the government has an obligation to protect the interests not only of the propertied classes but also of those without. This obligation provides another significant limitation on the power of the government. Locke suggests, however, that the obligation of the "ruling class" is made more effectual only if the members of that class can be persuaded that their authority and power come from the people, and that they have a responsibility to provide for the people. One of Locke's most important insights is that the rulers' belief in popular sovereignty provides a greater restraint on political power than does any institutional arrangement such as divided government or checks and balances. Where this belief is absent, a liberal political system will not survive, a fact that is evidenced by the many failed attempts to impose liberal regimes where the conditions are not yet "ripe."

The Second Treatise is, in this respect, a rhetorical tour de force. It succeeds in persuading the ruling class to advocate, and actually to put in place, a political system that constrains its own power out of self-interest, in order to take into account the interests of all. Locke's awareness of the importance of grounding liberal government in an appropriate set of liberal beliefs is reminiscent of the great political theorists who came before him. The current widespread acceptance of that set of beliefs is suggestive of his role in teaching many of the theorists who followed him. The Second Treatise should be read by the citizens of any liberal democracy as a reminder of the principles upon which their government is based and the reasons for which they believe it is preferable to any other.

Joseph Carrig holds a Ph.D. in political science from the University of Pennsylvania. He specializes in political theory and American government, and he writes frequently on the works of John Locke.