This work explores the foundations of a deeply felt intuition that pervades American jurisprudence: the act-omission distinction ( AvO ). I conclude that Hume\u27s understanding of the origins of our conception of duties presaged an important insight from modem evolutionary theory: our tendency to engage in altruistic conduct begins, although it clearly does not end, with the physical reality of personal kinship in an unkind world, and it tends to extend out in a social network of ever-diminishing strength the farther we move from the nuclear family. The thesis begins with the observation that we privilege acts over omissions for purposes of accountability, because the psychological constituents of human ... nature, like the anatomical...