The first statement is a common thought. The second is an evolution and exploration of the first. And the third and fourth are further explorations of the first. These statements are true based on the transparent path of thought progression I lay in my books Liberty Defined and Morality Defined.

In them I discuss the practical applications of self ownership, not the philosophical portion that states one cannot not own themselves because 'X' reason. So in understanding the practical application of self ownership one understands the statement of "all human activity is economic activity." And that is derived from understanding what wealth is, why it has value, and how it is created; which is all based on the premise of self ownership.