This is an idea that virtually defines the Discourse. It is summed up in the quote from Aristotle that Rousseau uses to preface his work: "What is natural has to be investigated not in beings that are depraved, but in those that are good according to nature." Aristotle's point is that because what is "natural" is also sets a standard for people to follow, it is vital to look at the correct "nature." Rousseau argues that we need to investigate natural man in the correct way because the idea of nature is used to justify harmful and depraved inequality. The best way to undermine modern inequality is to reveal that it is artificial and "unnatural."
Uncovering the natural is a powerful and difficult act. It involves stripping back many layers that have been deposited on top of man's true nature by centuries of development. This act is powerful because it sets up an unfavorable comparison with modern societies. When Rousseau considers what is natural in man, he discovers that it includes none of the qualities that many would think of as central to human existence, such as reason and language. Nor does it imply structures such as property, law and moral inequality. However, uncovering the natural can only be undertaken in an imaginary way. Rousseau is clear that it is impossible to return to the state of nature, and that his investigations are only "conjectures." Despite its considerable power, this act of uncovering cannot happen in practice.
The theme of corruption is closely related to that of nature. Corruption is what Rousseau feels he has to strip away to get to the real nature of man. Corruption is also an important part of the process of human development that he describes. At the same time that human reason develops, and enlightenment emerges, man is corrupted and undergoes a decline from his original condition. Rousseau is clear that this corruption is both a mental and a political process. Mental corruption occurs as man becomes subject to a new system of needs and to the operation of amour propre. His corruption is evident in the attention he now pays to the opinion of others, his loss of basic pity for other creatures, and his general dissatisfaction with life. As Rousseau puts it in Part Two of the Discourse, modern man has "nothing more than a deceiving and frivolous exterior, honor without virtue, reason without wisdom, and pleasure without happiness".
Corruption is also a political phenomenon, however. Rousseau's description of modern society shows that it is based upon a trick played on the poor, and that it compares unfavorably with both the state of nature and with early society. Political society is corrupt because it is based on a lie, which is used to exploit those who believed that it would protect their freedom. Ultimately both kinds of corruption reinforce each other.
This theme only becomes clear towards the end of Part Two. Rousseau analyzes many of the problems of modern society, but this is perhaps the most important. The system of needs that enslave modern man and the operation of "amour proper" make him inauthentic, or untrue, both to himself and to others. He cannot behave in an authentic way towards his fellow citizens, because he is continually thinking about how to deceive and dominate them. Those who founded society and first created property deceived others, and their heirs act in a similar way. More importantly, modern man is not true to himself. This is partly because he is controlled by ridiculous needs and "factitious passions," but also because his very nature is inauthentic. Modern man has evolved so far from true human nature that he would be almost unrecognizable to savage man. Modern life is thus built around a lack of authenticity.
In contrast, savage man is both true to himself and to others. He has limited needs and no desire to dominate others. Indeed, his few dealings with other humans are initially for reproduction alone. There is no possibility of him using or deceiving others, because he has no notion of deceit. Savage man can only "be": Modern man is forced to "be" and to "appear," and so becomes inauthentic.
Need is the key diving force behind modern society. Needs result from the passions, which make men desire an object or activity. In the state of nature, needs are simple and restricted to those that are necessary to human survival: food, rest and sex. As societies and cooperation develop, however, men have more leisure time to fill. The result is a development of more and more needs, which gradually become necessities. Rousseau means things like socializing, exotic food and entertainment. Although they are initially pleasurable, these new needs bind men together and shape their lives. Ultimately, needs control men and make them the slaves of others. When a man requires others to fulfill his needs, or simply the needs of other people, another can dominate him. Unnecessary needs are the foundation of modern inequality, according to Rousseau.
Rousseau's sustained analysis of this theme is a vital part of the Discourse. Like human nature, need is a concept that changes and becomes corrupt as man develops. The idea of a system of needs influenced Hegel's idea of civil society, and should provoke reflection today. In an age of prosperity, consumer goods and the mass media, Rousseau's depiction of men who are enslaved to imaginary needs seems very apt.
Freedom is an important theme in the Discourse and in the Social Contract. The only purpose of the state, Rousseau argues, is to secure the freedom of the citizens, and the worst system of government is that in which the most people are not free. Indeed, the Social Contract is an attempt to create a society in which freedom for all is possible. In contrast, the Discourse describes a situation in which no one can really be free.
The domination of one person by another reduces that person's freedom to act. Property and laws also affect the citizen's freedom, but those who agree to them generally believe that they are a reasonable restraint on their liberty. In practice, however, real freedom within society is impossible because inequality and property lead inevitably to domination. Only in the state of nature, or in a radically different type of society, could real freedom exist. This is an insight that Marx picked up in the Communist Manifesto.
Rousseau's description of freedom does not rely on political institutions and laws alone, however. It also includes an idea of psychological freedom, or freedom from need. Modern man is not free partly because others dominate and exploit him, but also because he is the slave of his own needs. As long as man needs others, or relies upon their opinions, he can never be free. Savage man is free in both senses of the term, because he does not depend on others, and cannot be dominated. Rousseau is clear that this type of primitive freedom is no longer possible in the modern world: to find out what sort of freedom he thinks can be achieved, you need to read the Social Contract.