Local contexts and local meanings

Stalnaker (1978) made two seminal claims about presuppositions. The most influential one was that presupposition projection is computed by a pragmatic mechanism based on a notion of 'local context'. Due to conceptual and technical difficulties, however, the latter notion was reinterpreted in purely semantic terms within 'dynamic semantics' (Heim 1983). The second claim was that some instances of presupposition generation should also be explained in pragmatic terms. But despite various attempts, the definition of a precise 'triggering algorithm' has remained somewhat elusive. We discuss possible extensions of both claims. First, we offer a reconstruction of 'local contexts' which circumvents some of the difficulties faced by Stalnaker's original analysis. We preserve the idea that local contexts are computed by a pragmatic mechanism that aggregates the information that follows from an incomplete sentence given the global context; but we crucially rely on a modified notion of entailment ('R-entailment'), whose plausibility should be assessed on independent grounds. Second, we speculate that local contexts might prove necessary (though by no means sufficient) to understand how some presuppositions are triggered. In a nutshell, we suggest that a presupposition is triggered when the semantic contribution of an expression to its local context is in some sense 'heterogeneous'. Without giving an analysis of the latter notion, we note that this architecture implies that presuppositions should be triggered on the basis of the meaning that an expression has relative to its local context (what we call its 'local meaning'); we sketch some possible consequences of this analysis.