The harm principle, originally associated with John Stuart Mill
is best explicated, not as an expression of the simple relationship between two individual parties, but ... as an indirect way to advance overall social welfare.
Harms by aggression and harms by competition are too easily treated as parallel violations of the single prohibition against harm to others; and their profound differences are not grasped solely by reference to the fate of the immediate parties to any dispute, but by their overall social consequences.
The prohibitions against force and fraud block destructive "negative-sum-games" [ = gain of the one is the loss of the other, G.T.] that impoverish society.
In contrast, harm by competition, which so often prompts extensive state regulation, fosters positive-sum-games [ = where all parties win, G.T.] that make maximum use of both human and natural resources.
Now, consider the benefit principle
under which I must compensate you for the benefits you confer upon me against my will. The principle is something of an anomaly: normally by first making a gift to you, I cannot force you to make a gift to me.
But the usual autonomy principle is suspended in some limited settings, chiefly those in which necessity and mistake undermine the effectiveness of voluntary agreement.
When voluntary transactions are bocked, private parties may initiate forced exchanges that allow them to demand compensation tomorrow by providing assistance today.
This innocuous principle of the common law finds its most potent application in "social contract" theory.
Social contracts are not just convenient legal fictions that allow the state to pile endless obligations on individuals without their consent. Rather the term contract presupposes that the desirable social arrangements imitate private contracts by allowing all parties to be better off through the imposition of reciprocal obligations on all citizens.
The term social then reminds us that these arrangements are imposed from above to overcome the transactional difficulties that stand in the path of comprehensive voluntary arrangements.
Quoted from Epstein, R. (1998) Principles for a Free Society. Reconciling Individual Liberty with the Common Good, Cambridge, MA, Basic Books - pp 6-7.