For Rousseau, the questions of why and how human beings are naturally equal and unequal, if they are unequal at all, are fundamental to his larger philosophical enquiry. To form his critique of modern society’s problems, he must show that many of the forms of inequality endemic to society are in fact not natural and can therefore be remedied. His conclusions and larger line of reasoning in this argument are laid out in Discourse on Inequality, but the basic thrust of his argument is that human inequality as we know it does not exist in the state of nature. In fact, the only kind of natural inequality, according to Rousseau, is the physical inequality that exists among men in the state of nature who may be more or less able to provide for themselves according to their physical attributes.
Accordingly, all the inequalities we recognize in modern society are characterized by the existence of different classes or the domination and exploitation of some people by others. Rousseau terms these kinds of inequalities moral inequalities, and he devotes much of his political philosophy to identifying the ways in which a just government can seek to overturn them. In general, Rousseau’s meditations on inequality, as well as his radical assertion of the notion that all men are by-and-large equal in their natural state, were important inspirations for both the American and French Revolutions.