This contribution investigates the interactions between the (mental) lexicon and pragmatics. It aims to give an overview about pragmatic phenomena that are connected with the semantic underspecification of lexical items. Cases in point are the pragmatics of adjectives, effects of negative strengthening, systematic polysemy, the distribution of lexical and productive causatives, blocking phenomena, the interpretation of compounds, and many phenomena presently discussed within the framework of Cognitive Semantics. After emphasizing some important consequences of the traditional view of lexical semantics -- the contrastive analysis of lexemes within the Katz-Fodor tradition of semantics --, several phenomena are collected that seem to conflict with the theoretical settings made by it. These phenomena are taken as arguments in favor of a particular account of the division of labor between lexical semantics and pragmatics. This account combines the idea of (radical) semantic underspecification in the lexicon with a theory of pragmatic strengthening, based on conversational implicatures. The basic pragmatic mechanism can be expressed within the framework of (bidirectional) optimality theory for interpretation. It is suggested that this approach may provide a principled account of several of the lexical-pragmatic phenomena that are currently discussed. 1

In this paper I argue that the `ambiguity' between mention-all and mentionsome readings of questions can be resolved when we relate it to the decision problem of the questioner. By relating questions to decision problems, I (i) show how we can measure the utilities of both mention-all and mention-some readings of questions, and (ii) give a natural explanation under which circumstances the mention-some reading is preferred.

INTRODUCTION Lexical Pragmatics is a particular account of the division of labor between lexical semantics and pragmatics (e.g. Blutner 1998). It combines the idea of (radical) semantic underspecification in the lexicon with a theory of pragmatic strengthening (based on conversational implicatures). In the core of this approach is a precise treatment of Atlas & Levinson's (1981) Q- and I-principles and the formalization of the balance between informativeness and efficiency in natural language processing (Horn's 1984 division of pragmatic labor). In a roughly simplified formulation, the Iprinciple seeks to select the most coherent interpretation, and the Q-principle acts as a blocking mechanism which blocks all the outputs which can be grasped more economically by an alternative linguistic input. Recently, these mechanisms have been implemented within a bidirectional version of optimality theory (OT) which aims to integrate expressive and interpretive optimization (Blutner 1999