LightRider, I agree that the population wouldn't shrink. So let's say humans, due to very efficient production, want for nothing and have much more leisure time. Let's say that in his leisure time, one person creates beautiful artwork that appeals to a huge audience. How does he determine who gets to own his art, and what do they give him in exchange?
That is a question of personal and social values, which are largely informed by the environment and biopsychosocial pressures on said person and society.
