Visible Meaning: Sign language and the foundations of semantics

While it is now accepted that sign languages should inform and constrain theories of 'Universal Grammar', their role in 'Universal Semantics' has been under-studied. We argue that they have a crucial role to play in the foundations of semantics, for two reasons. First, in some cases sign languages provide overt evidence on crucial aspects of the Logical Form of sentences, ones that are only inferred indirectly in spoken language. For instance, sign language 'loci' are positions in signing space that can arguably realize logical variables, and the fact that they are overt makes it possible to revisit foundational debates about the syntactic reality of variables, about mechanisms of temporal and modal anaphora, and about the existence of dynamic binding. Another example pertains to mechanisms of 'context shift', which were postulated on the basis of indirect evidence in spoken language, but which are arguably overt in sign language. Second, along one dimension sign languages are strictly more expressive than spoken languages because iconic phenomena can be found at their logical core. This applies to loci themselves, which may simultaneously function as logical variables and as schematic pictures of what they denote (context shift comes with some iconic requirements as well). As a result, the semantic system of spoken languages can in some respects be seen as a simplified version of the richer semantics found in sign languages. Two conclusions could be drawn from this observation. One is that the full extent of Universal Semantics can only be studied in sign languages. An alternative possibility is that spoken languages have comparable expressive mechanisms, but only when co-speech gestures are taken into account (as recently argued by Goldin-Meadow and Brentari). Either way, sign languages have a crucial role to play in investigations of the foundations of semantics.