more from Laura Schroeter

Single Idea 14702

[catalogued under 19. Language / C. Assigning Meanings / 10. Two-Dimensional Semantics]

Full Idea

At first glance necessity and possibility can be fully expressed by quantifying over all possible worlds, but this cannot capture 'Possibly everything actually red is also shiny'. This needs a double-indexed framework, with worlds playing two roles.

Gist of Idea

If we introduce 'actually' into modal talk, we need possible worlds twice to express this


Laura Schroeter (Two-Dimensional Semantics [2010], 1.2.1)

Book Reference

'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [], p.9

A Reaction

She points out that this also applies to tense logic, for the notion of 'now'. The point is that we not only need a set of possible worlds, but we also need a procedure (the 'Actuality' operator A or @) for picking out one of the worlds as special.