“…There have been numerous attempts to provide a formal definition of supererogation, to the point where Heyd () suggests that the concept is one “that cannot be captured by a strict formal definition.” Despite Heyd's pessimism, the recent literature on the topic seems to be approaching a consensus on at least two issues concerning how to define supererogation. The first is that supererogatory acts are morally optional , meaning that both their performance and their omission are morally permissible (e.g., Archer, , p. 334; Ferry, ; Horgan & Timmons, , p. 37; Portmore, , p. 91; McElwee, , p. 506).…”