| 7791 | The simplest of the logics based on possible worlds is Lewis's S5 [Lewis,CI, by Girle] |
| 14973 | In S5 all the long complex modalities reduce to just three, and their negations [Cresswell] |
| 13604 | Real possibility and necessity has the logic of S5, which links equivalence classes of worlds of the same kind [Ellis] |
| 14686 | S5 modal logic ignores accessibility altogether [Salmon,N] |
| 14691 | S5 believers say that-things-might-have-been-that-way is essential to ways things might have been [Salmon,N] |
| 14693 | The unsatisfactory counterpart-theory allows the retention of S5 [Salmon,N] |
| 14627 | S4, and therefore S5, are invalid for metaphysical modality [Salmon,N, by Williamson] |
| 9560 | S5 provides the correct logic for necessity in the broadly logical sense [Fine,K] |
| 9065 | S5 collapses iterated modalities (◊□P→□P, and ◊◊P→◊P) [Keefe/Smith] |
| 9748 | System S5 has the 'reflexive', 'symmetric' and 'transitive' conditions on its accessibility relation [Fitting/Mendelsohn] |
| 14626 | In S5 matters of possibility and necessity are non-contingent [Williamson] |
| 15131 | If metaphysical possibility is not a contingent matter, then S5 seems to suit it best [Williamson] |
| 13708 | S5 is the strongest system, since it has the most valid formulas, because it is easy to be S5-valid [Sider] |
| 7793 | ◊p → □◊p is the hallmark of S5 [Girle] |
| 7795 | S5 has just six modalities, and all strings can be reduced to those [Girle] |
| 18814 | 'Absolute necessity' would have to rest on S5 [Rumfitt] |
| 12204 | The logic of metaphysical necessity is S5 [Rumfitt] |
| 19032 | S5 is undesirable, as it prevents necessities from having contingent grounds [Vetter] |