Why did Rousseau see private property as a cause of inequality?

In his Discourse on the Origin of Inequality, Jean-Jacques Rousseau argued that the introduction of private property was a pivotal moment that fundamentally corrupted human society and deepened inequality.12

Rousseau believed that in the original state of nature, humans were solitary, healthy, and free, living in a condition where the earth belonged to no one. As people began to form societies and settle into permanent dwellings, they developed social comparisons, jealousy, and pride. The subsequent establishment of private property exacerbated these tensions, as it necessitated the creation of law and government to protect the possessions of those who had acquired them.12

Rousseau viewed this development as a "fraudulent" social contract. While civil society was ostensibly formed to provide peace, it primarily served the interests of the wealthy by transforming de facto ownership into rightful, legally protected property, thereby keeping the poor dispossessed. Consequently, Rousseau saw property not as a natural right, but as a catalyst for vice and a structural barrier that alienated humans from their original innocence and equality.12