The unity of morphology: on the interwovenness of the derivational and inflectional dimension of the word

A common trait of many approaches to morphology is that a distinction is made between ‘derivation’ on the one hand and ‘inflection’ on the other, the former dealing with words the latter with word forms. As is well-known, however, it is extremely hard to characterize this distinction in objective terms. In Bybee (1985: 81) the stand is taken that it may well be that the criterion of ‘obligatoriness’ is the only criterion which provides a discrete division between derivational and inflectional processes. According to this view, inflectional morphemes are those whose appearance in a particular syntactic position is compulsory. It seems to me, however, that even this criterion is not as clear as Bybee suggests. The fact is, that particularly many categories of so-called inherent inflection are not compulsory in the above sense. In many languages, categories such as nominal plurals or comparatives and superlatives of adjectives are not dictated by sentence structure as, for instance, person or number marking on verbs is. Nonetheless, these categories have traditionally always been considered instances of inflection. Why is that so? The answer to this question, it seems to me, is that these categories, somehow or other, ‘participate’ in the syntactic structure that they form part of, something which prototypical derivational categories never do.1 In many languages the category of nominal plurals, for instance, dictates plural marking on the verb. Put differently, in a language like Dutch nominal plurals take part in the concord system, a fact which renders these forms a status which is fundamentally different from purely derivational categories