There is no place more informative than theories of justice for identifying the numerous conflicting theories of human nature possessed by human observers. For example, social contract theories in their several forms assume that humans (or at least deserving males) possess radical agency and an incredibly expansive understanding of human behavior. From that assumption, humans are assigned large amounts of personal responsibility–blame and credit flow easily from this worldview.
I do not think there is anything like Rawls’ theory of justice without the assumption that humans are risk averse, and thus likely to accept the mandate to maximize the welfare of those with the minimum amount of social well-being. Draw down the veil of ignorance, and the fear of belonging to the cohort at the bottom seizes the mind IF WE ARE RISK AVERSE.
A more left-wing theory of justice emerges as Martha Nussbaum explains theCapabilities Approach to Justice in a succinct You Tube clip. The source for the distribution of the desired capabilities must be a cooperative venture, probably the state. She claims that we as a species are motivated by love to respect one another.
The fascinating thing to me about such theories is how rarely thinkers at this level of reflection feel a need to provide any empirical basis for their wishful thinking beyond colorful anecdotes. Martha Nussbaum in her many books and articles explains and documents the need for this more positive form of freedom. But why should we believe that any of the human nature assumptions that anchor these elaborate theories are a reliable basis for human action?