Stem alternations and multiple exponence

In a canonical inflectional paradigm, inflectional affixes mark distinctions in morphosyntactic value, while the lexical stem remains invariant. But stems are known to alternate too, constituting a system of inflectional marking operating according to parameters which typically differ from those of the affixal system, and so represent a distinct object of inquiry. Cross-linguistically, we still lack a comprehensive picture of what patterns of stem alternation are found, and hence the theoretical status of stem alternations remains unclear. We propose a typological framework for classifying stem alternations, basing it on the paradigm-internal relationship between the features marked by stem alternations versus those marked by affixes. Stem alternations may mark completely different features from the affixes (§2), or the same features (§3). Within the latter, the values may match (§3.1) – a rare situation – or be conflated (§3.2). Conflation in turn may involve natural semantic/morphosyntactic classes (§3.2.1), or phonological conditioning (§3.2.2), or be morphologically stipulated (§3.2.3). These patterns typically reveal stems’ continued allegiance to lexical as opposed to inflectional organizing principles