Abstract
Dynamic models of paradigm change can elucidate how the simplest of processes
may lead to unexpected outcomes, and thereby can reveal new potential
explanations for observed linguistic phenomena. Ackerman & Malouf (2015)
present a model in which inflectional systems reduce in disorder through the
action of an attraction-only dynamic, in which lexemes only ever grow more
similar to one another over time. Here we emphasise that: (1) Attraction-only
models cannot evolve the structured diversity which characterises true
inflectional systems, because they inevitably remove all variation; and (2)
Models with both attraction and repulsion enable the emergence of systems that
are strikingly reminiscent of morphomic structure such as inflection classes.
Thus, just one small ingredient -- change based on dissimilarity -- separates
models that tend inexorably to uniformity, and which therefore are implausible
for inflectional morphology, from those which evolve stable, morphome-like
structure. These models have the potential to alter how we attempt to account
for morphological complexity.