Il polimorfismo tra disordine e regolarità: i tipi habù e habiù nei volgari veneti medievali

The aim of this paper is to discuss some cases of polymorphism in the empirical domain of the ancient Venetan dialects, notably the existence of two competing strategies for the formation of the perfect participles of avere and other verbs. Before dealing with it, it will be addressed a methodological topic, that is, which kind of linguistic system can be reconstructed from data where optionality is in order, especially in morphology. I will propose, then, to treat polymorphisms in the light of the typological theory of canonicity, which allows evaluating irregular morphology according to comparative criteria. Under this view, it will be shown that the optionality between e.g. the expected form of the perfect participle habù and the marked form habiù related to the present subjunctive, is coherent with an analogical trend well attested in the Northern Italian dialects since the Middle Ages. Having identified this diachronic pattern is relevant for at least two reasons: first, it demonstrates that even morphological disorder can be accounted for within a systemic picture; secondly, it shows that diachronic issues can give a contribution to the discussion about canonicity. Beside this, the possibility that under specific conditions subjunctive stems interfere with the formation of the perfect participle, allows to consider the relationships within Norther Italian medieval varieties more carefully.