Logic and Language

Johannes Marti: The Four Dimensions of Two-Dimensionalism

Speaker: Johannes Marti
Title: The Four Dimensions of Two-Dimensionalism
Time: 16:00 - 17:30
Location: Vendelstraat 8, room 307 (the old phil. library)

In two-dimensional semantics the extension of expressions is relativized to pairs (c,w) with two components. One of them w, which is called "world of evaluation", is a possible world that is shifted by the modal necessity operator. The other component c, called the "context", is used to model the context-dependence of semantic values. The context is used to model different kinds of context-dependence that are associated to different interpretations of the framework:

1. Indexicality. The meaning of indexicals and demonstratives depends on the context. This type of context-dependence is modeled in the original two-dimensional system by Hans Kamp and in the work of David Kaplan.

2. Causal Reference Fixing. According to a Kripkean theory of reference the meaning of proper names and natural kind terms depends on the causal origin of their use in the context. This type of context-dependence together with the first type is represented by the context component on the the epistemic interpretation of two-dimensional semantics by Frank Jackson and David Chalmers.

3. Linguistic Conventions. In different context different linguistic conventions can determine the meaning of the expressions uttered. This type of context-dependence, together with the previous two, is captured by the context component under the metasemantic interpretation of the framework that is championed by Robert Stalnaker but is also present in early work by Bas van Fraassen.

In "On Considering a Possible World as Actual" Stalnaker suggests a three-dimensional modal logic in which context-dependence of the first type is distinguished from context-dependence of the two other types. Independently, in "Truth in Virtue of Meaning" Gillian Russell develops a three-dimensional system which distinguishes between context-dependence of the first and second type but does not consider the third type. Based on Russell's work, I present a four-dimensional semantics in which all three types of context-dependence are treated separately. The three different versions of two-dimensional semantics embed into this four-dimensional system. This helps to clarify the relation between the different interpretations of two-dimensionalism.