Derek Matravers in the TLS:
Jean-Jacques Rousseau (1712–78) is, perhaps more than any other philosopher, a contradictory figure. He is a predecessor of liberalism and a theorist of fascism; a champion of the Enlightenment and its most severe critic; a Classicist critic of Romanticism and vice versa; and an advocate of humane, child-centred education, despite giving up his own five children to an orphanage and almost certain death. His reputation these days rests primarily on his political philosophy (in particular, On the Social Contract), his autobiography (The Confessions), and a part novel, part philosophical treatise, and part syllabus for progressive education (Émile).
Rousseau is very quotable – never more so than at the beginning of Book One, Chapter One of the Social Contract: “Man is born free, and everywhere he is in chains”. This appears to capture the view with which he is most famously associated: that man is born naturally good only to be corrupted by society. Another quotable opening sentence, this time from Émile, seems to support this: “God makes all things good; man meddles with them and they become evil”. This phrase is misleading on two accounts. First, Rousseau is clear that the situation of humankind in its pre-societal state is not to be envied. Second, he did not think it our inevitable fate to be corrupted by society; indeed, the point of the Social Contract is to provide a blueprint for a society in which people are able to flourish.
It was fairly standard in the seventeenth and eighteenth centuries to compare humankind before societies formed (the “state of nature”) to our condition in society. This was not an attempt to write history from the armchair, but rather a thought experiment; a comparison between things then with how they are now, to shine a light on the advantages of states. Rousseau had a weakness for the rhetorical flourish – and his powers of eloquence sometimes served to highlight the notion that leaving the state of nature had been a catastrophe.
More here.