 Two dimensional semantics is a variant of possible world semantics that uses two (or more) kinds of parameters in truth evaluation, rather than possible worlds alone. For example, a logic of indexical expressions, such as ‘I’, ‘here’, ‘now’, and the like, needs to bring in the linguistic context (or context for short). Given a context \(c = \langle s, p, t\rangle\) where \(s\) is the speaker, \(p\) the place, and \(t\) the time of utterance, then ‘I’ refers to \(s\), ‘here’ to \(p\), and ‘now’ to \(t\). So in the context \(c = \langle\)Jim Garson, Houston, 3:00 P.M. CST on 4/3/\(2014\rangle\) ‘I am here now’ is T iff Jim Garson is in Houston, at 3:00 P.M. CST on 4/3/2014.