A Social system is a system that uses communication in its autopoiesis. While there would be no communication without minds, communication does not 'follow' from minds and cannot be 'reduced to it, as if minds 'entailed' communication.
A Social system is not a natural reality, but rather a figment of thought, a relation between concepts, not actual things.
A Social system is an organized pattern of behavior including actions, interactions, roles, symbolic meanings, choices, and so forth, but not individual human beings.