On the origin of the absolute vs. conjunct opposition in Insular Celtic

Despite more than a century of research, the origin of the Insular Celtic double system of verbal inflection is still debated. In this paper, we defend the thesis that the set of absolute endings originated by the agglutination of a subject clitic to the verb form. This clitic marked the declarative (vs. relative) use of verbs, since its distribution was complementary to that of the relative marker *yo. The present indicative as well as the preterite (in both the absolute and conjunct inflection) of one strong verb (berid ‘bring’) and one weak verb (lécid ‘leave’) are reconstructed according to this theory. For compound verb forms, the clitic ~ *yo alternation can be posited as well. The cases in which the distribution of initial mutations on the verb stem after preverbs does not follow the diachronic phonological rules of Old Irish (that is, there is no lenition after preverbs originally ending in a vowel) are accounted for from a synchronic standpoint. This “anomalous” behaviour can be explained by positing that a functionally relevant (morphological) system of mutations had replaced the previous phonology-based system.