In light of a functional perspective on nominalization, this paper investigates the nominalization marker =ay in two Formosan languages Kavalan and Amis. In addition to denoting persons/things or events, the marker also indicates perfectivity or emphasis. The latter non-referring functions of =ay are argued to derive from its grammatical status as an epistemic modality marker conveying a speaker’s strong commitment to a proposition, which presumably has been grammaticalized from its referring functions. Several types of evidence are presented to support the hypothesized grammaticalization path, including synchronic-intralingual, synchronic-interlingual, historical, and typological.
On the grammaticalization of nominalization marker =ay in Kavalan and Amis: a contrastive study