Introduction

Abstract

Abstract This volume is concerned with questions raised by two apparently conflicting observations on the inventory of expressions (and in particular, lexical items) in natural languages. On the one hand, it is widely assumed that the rules of grammar include so-called blocking constraints, which prohibit the co-existence of forms that are identical in meaning, but differ in form. On the other hand, it can be shown that many natural languages exhibit examples of non-blocking and at least some degree of linguistic variation involving exactly this type of (morphological) doublets which can be said to compete for realizing one and the same meaning. In the following we are going to introduce the different types of blocking that are discussed in the literature as well as non-blocking effects to set the contributions in this volume in their context.