Rousseau turns from the physical condition of humans in nature to what he calls their “metaphysical and moral side” (113). He acknowledges that humans are distinct from other animals, which are essentially the same throughout their lifespan and subsequent generations. Individuals and societies can engage in self-directed change and therefore possess a spiritual dimension in addition to a physical form. However, for Rousseau, that same desire for improvement is also the primary cause of degeneration. He generally regards humankind’s efforts to improve themselves as having backfired, making their lives more complicated and multiplying potential sources of misery.

Rousseau argues that Humanity’s Capacity for Reason is a product of its passions since the primary use of reason is to achieve what one desires. When a person learns that they can achieve what they want, their reasoning becomes more sophisticated so that they can satisfy an ever-expanding set of desires. For a human in nature, by contrast, “his desires do not exceed his physical needs” (116), and nature provides him with what he needs. Rousseau then discusses how natural human beings on their own could never have developed the skills necessary for modern life and would never have had the inclination to do so.