 Interpreting the threshold concept as an element of a sufficiency conception of intergenerational justice can take a number of different forms (see Benbaji 2005: 316–321 and 2006; Casal 2007: 312–326; Huseby 2010a). A plausible version is characterized by two theses, namely by what scholars have called the “Positive Thesis” (see especially Casal 2007: 298–299) and the “Shift Thesis” (Shields 2016: 34–35). The Positive Thesis states that we have weighty non-instrumental reasons to secure at least enough of some benefit(s). According to the Shift Thesis, 