 If we add RMon to B we get the system V of David Lewis. John Pollock (1976) proposed the system SS obtained by adding SM and CS to B. Lewis’ “official” axiomatization of the logic of counterfactuals is the system VC that is obtained by adding SM and C to V. The extension of V with just SM is the system VW. Finally, system C2 with the incorporation of CEM into VC is Stalnaker’s logic of conditionals. As  Table 6  makes clear, principles like CS, CMon, RMon, and CEM in particular are controversial, they have all been subject to philosophical discussions.