Background
Rousseau was born in the Calvinist republic of Geneva. At 16 he rebelled, ran away and converted to Catholicism, and then became the lover of a French aristocrat, where he studied in her library. After tiring of her, he moved to Paris and befriended the circle of intellectuals known as the Philosophes, who were quintessential enlightenment philosophers. Thus, the key points of his intellectual background was as follows:
(1) From the works of Bacon and Newton, enlightenment thinkers developed the idea that the whole world must be governed by laws, and that these laws were set by God
(2) That there were similarly a set of moral laws grounded in human nature
(3) That these laws were best discovered by looking at human needs (a priori) and by inspecting and observing the best of people (a posteriori)
The dominant view of the time was that man was at his best when he was civilised, studying the sciences and progressing materially as a result.
In 1750 he entered an essay competition, whose subject was the connection between scientific progress and morality (i.e. does scientific progress aid moral purity?). His essay argued that not only did scientific progress not make people more moral, but that it actually made them less moral. He asserted that scientific progress, and more generally civilisation, distorted human nature and caused moral decline. Despite being contrary to the enlightenment doctrine, he won the competition and went on to amend the essay and publish it as First Discourse.
The First Discourse and his emerging political program
The central thesis of the First Discourse is that perhaps civilisation has distorted and warped human nature, having a negative effect upon people. He claimed that basing any theory upon human nature as it can be observed in society is therefore flawed, and that to study human nature we must consider a hypothetical savage. Rousseau developed the idea of a noble savage who would have good health (due to no over-eating, drinking, laziness, etc.), no need to co-operate except for procreation, therefore no language and also therefore no foresight.
The noble savage has three main characteristics:
1) A strong instinct to self-preservation
2) Compassion (i.e. the capacity to suffer (passion) with (com-))
3) Instructive autonomy, a love of freedom
Objection: how we can we explain the transition from savage to a corrupted civil citizen?
Rousseau:
1) At first, savages require short-term co-operation for short-term gains, for example the co-operation of a hunting pack to hunt and bring down a large animal. Such co-operation would require some primitive language, and a degree of foresight (e.g. to say "you hide there, I throw this").
2) This simple inter-dependence would lead to pride and a consciousness of difference
3) It would also make sense for savages to shelter communally, leading to the formation of the family, the creation of gender roles, and romantic love
4) Pride would inevitably lead to conflict, which would escalate towards tribal wars; these would necessitate the development of metallurgy, agriculture and other more complex forms of social organisation
5) Inequality of ability would lead to private property and material inequality
6) Eventually the need to co-operate to prevent conflict and protect material interests would lead to the formation of the state
The inevitability of the state led Rousseau to ask a difficult and age-old question: where does the right of the state to govern others come from? He thought:
1) Not from conquest; might cannot be considered right
2) Not from normal contracts; they are manifestly unequal, since they sacrifice liberty for security, and bind future generations
There must governance based upon the expression of all citizens' views, upon the General Will. This would be a kind of social contract.