The boundaries of inflection

A central question in the realisation of inflectional and inflection-like categories is the fuzzy boundary between morphology and syntax, i.e. morphosyntax. The aspectual categories in English (Continuous and Perfect) and Passive are not realised morphologically but syntactically, by concatenation with auxiliary verbs. Consequently, they are not inflections in the morphological sense of the term; nevertheless, they are semantically closely related to the interpretation of verbal inflectional categories and to the quantification of events and event structures. Similarly, nominal quantificational categories such as Definiteness are inflection-like, and relate to the semantic interpretation of Number and Case.

Another morphosyntactic issue concerns the status of Comparison. Traditionally, it is classified as an inflection. However, there are grounds for classifying Comparison as a derivational category, rather than as an inflectional category:

1. In contrast to inflections, words of different degrees of Comparison have different syntactic distributions: wider than ..., the widest of ..., as wide as .... On the other hand, the different syntactic distributions are expressed in relation to grammatical words, which might be claimed to be a form of periphrastic inflection, rather like genitive of versus the inflectional -s.
2. In related, but more highly inflecting languages such as German, stems are concatenated with comparative suffixes, which are then inflected with the inflectional suffixes which realise Case, Number and Gender. These categories are not otherwise agglutinative, with the minimal exception of dative plurals nouns, whereas derivational suffixation is typically agglutinative. On the other hand, the Comparison suffixes occur after other derivational suffixes, but before the inflectional suffixes, so the ordering gives no detailed clues.