Which of these principles is common to both lamarck’s and darwin’s theories of evolution?
species developed new features in order to survive in a changing environment.
all organisms are related to and descended from a common ancestor.
environment selects who will survive by allowing the best adapted organisms to survive.

you did not attach the discourse, but i assume it to be the discourse on the origin and basis of inequality among men (the original titile in french is: "discours sur l'origine et les fondements de l'inégalité parmi les hommes"), also know as "second discourse". in this discourse, jean-jacques rousseau emphasizes that private property is the basis of all inequalities.

therefore, what enabled the old regime to maintain as long as it did was private property.

where is the scientific experiment?