"Back in the day, in Hanson's farmer epoch, public morality was maintained in part by cultivating in people a sense of gratitude towards God/the universe/society/one's parents/the resident nepotist with a sword; that their existence entailed debts that in principle couldn't be repaid. Nowadays under liberalism we've in principle thrown that out but everybody's still linked in a web of very explicit debts, and the web doesn't in principle have a center."

(You might say that this is a massive oversimplification to the extent that it's true, and you'd be right, of course.)