Zero or null morphology refers to morphological units that are devoid of phonological content. Whether such entities should be postulated is one of the most controversial issues in morphological theory, with disagreements in how the concept should be delimited, what would count as an instance of zero morphology inside a particular theory, and whether such objects should be allowed even as mere analytical instruments. With respect to the first problem, given that zero morphology is a hypothesis that comes from certain analyses, delimiting what counts as a zero morpheme is not a trivial matter. The concept must be carefully differentiated from others that intuitively also involve situations where there is no overt morphological marking: cumulative morphology, phonological deletion, etc. About the second issue, what counts as null can also depend on the specific theories where the proposal is made. In the strict sense, zero morphology involves a complete morphosyntactic representation that is associated to zero phonological content, but there are other notions of zero morphology that differ from the one discussed here, such as absolute absence of morphological expression, in addition to specific theory-internal interpretations of what counts as null. Thus, it is also important to consider the different ways in which something can be morphologically silent. Finally, with respect to the third side of the debate, arguments are made for and against zero morphology, notably from the perspectives of falsifiability, acquisition, and psycholinguistics. Of particular impact is the question of which properties a theory should have in order to block the possibility that zero morphology exists, and conversely the properties that theories that accept zero morphology associate to null morphemes. An important ingredient in this debate has to do with two empirical domains: zero derivation and paradigmatic uniformity. Ultimately, the plausibility that zero morphemes exist or not depends on the success at accounting for these two empirical patterns in a better way than theories that ban zero morphology.
Eystein Dahl and Antonio Fábregas
Phonotactics is the study of restrictions on possible sound sequences in a language. In any language, some phonotactic constraints can be stated without reference to morphology, but many of the more nuanced phonotactic generalizations do make use of morphosyntactic and lexical information. At the most basic level, many languages mark edges of words in some phonological way. Different phonotactic constraints hold of sounds that belong to the same morpheme as opposed to sounds that are separated by a morpheme boundary. Different phonotactic constraints may apply to morphemes of different types (such as roots versus affixes). There are also correlations between phonotactic shapes and following certain morphosyntactic and phonological rules, which may correlate to syntactic category, declension class, or etymological origins. Approaches to the interaction between phonotactics and morphology address two questions: (1) how to account for rules that are sensitive to morpheme boundaries and structure and (2) determining the status of phonotactic constraints associated with only some morphemes. Theories differ as to how much morphological information phonology is allowed to access. In some theories of phonology, any reference to the specific identities or subclasses of morphemes would exclude a rule from the domain of phonology proper. These rules are either part of the morphology or are not given the status of a rule at all. Other theories allow the phonological grammar to refer to detailed morphological and lexical information. Depending on the theory, phonotactic differences between morphemes may receive direct explanations or be seen as the residue of historical change and not something that constitutes grammatical knowledge in the speaker’s mind.
Derivational morphology is a type of word formation that creates new lexemes, either by changing syntactic category or by adding substantial new meaning (or both) to a free or bound base. Derivation may be contrasted with inflection on the one hand or with compounding on the other. The distinctions between derivation and inflection and between derivation and compounding, however, are not always clear-cut. New words may be derived by a variety of formal means including affixation, reduplication, internal modification of various sorts, subtraction, and conversion. Affixation is best attested cross-linguistically, especially prefixation and suffixation. Reduplication is also widely found, with various internal changes like ablaut and root and pattern derivation less common. Derived words may fit into a number of semantic categories. For nouns, event and result, personal and participant, collective and abstract noun are frequent. For verbs, causative and applicative categories are well-attested, as are relational and qualitative derivations for adjectives. Languages frequently also have ways of deriving negatives, relational words, and evaluatives. Most languages have derivation of some sort, although there are languages that rely more heavily on compounding than on derivation to build their lexical stock. A number of topics have dominated the theoretical literature on derivation, including productivity (the extent to which new words can be created with a given affix or morphological process), the principles that determine the ordering of affixes, and the place of derivational morphology with respect to other components of the grammar. The study of derivation has also been important in a number of psycholinguistic debates concerning the perception and production of language.