Zero affixes in derivational morphology: Introduction

In this paper we offer an overview of the linguistic phenomena that have traditionally been handled by means of zero affixes and of the theoretical debate around the advantages and disadvantages of employing such null morphemes in theoretical modeling. While the advantage of positing zero affixes is straightforward from an empirical perspective (see inflectional syncretism and affixless category change, among others), their theoretical legitimacy has been controversially debated for several decades. In this overview, we present the main problems that have been brought forward against zero affixation and some of the mechanisms that have been proposed as an alternative. Finally, we show how the different articles in our edited collection contribute to this debate by addressing the following three research questions: (1) How do current theories of derivational morphology deal with linguistic phenomena that seem to involve zero affixes? (2) How do zero derivational affixes compare with their "overt analogues" (i. e. overt derivational affixes)? (3) What insights can we obtain from language-specific properties, typological generalizations and/or larger data-oriented studies on the question whether zero affixation is necessary in derivational morphology?