Constraints on allomorphy in inflexion.

This thesis is concerned with the search for constraints on the relationship between morphosyntactic properties and their inflexional exponents - more precisely, constraints on deviation from the maximally simple 'agglutinative' pattern of one exponent to one property and vice versa. Three principal constraints are proposed the Peripherality Constraint, the Paradigm Economy Hypothesis and the Systematic Homonymy Claim. The Peripherality Constraint specifies that the realisation of a morphosyntactic property may be 'sensitive to' a property realised more centrally in the word (i.e. closer to the stem) but not to one realised more peripherally, unless it is sensitive in the same way to all the more peripheral properties in the same category. The Paradigm Economy Hypothesis concerns the upper limit on the number of distinct inflexional paradigms (declension-types or conjugation-types) into which the inflexional resources (affixes, ablaut etc.) of any part of speech in any language may be organized. Given an appropriate definition of 'paradigm', this upper limit is engaged to be extremely strict no more paradigms may occur than are required to put all the inflexions to work. This hypothesis has to be relaxed to permit 'paradigm mixture', but only under narrowly specifiable conditions. The Systematic Homonymy Claim presupposes a distinction between those homonymies within an inflexional paradigm which are systematic and those which are accidental from the morphological point of view. It is argued that systematic homonymies can occur only under certain morphological conditions, the principal class of systematic homonymies ('syncretisms') being ones where the morpohsyntactic conditioning factors are realized sinultaneously with the neutralised properties. Evidence for these claims is drawn from a number of languages, both Indo-European and non-Indo-European (including Hungarian, Zulu, Turkish, Dyirbal and Fulfulde). Suggestions are made about priorities for future work on the theory of inflexional morphology.