The world’s smallest pronoun systems can eschew any of the following contrasts: (a) author-nonauthor, (b) participant-nonparticipant, (c) singular-nonsingular. This supports the view that features are mutually independent parameters ( Harbour 2011a , 2014a , 2016 ), but is problematic for Koeneman and Zeijlstra’s (2014) reworking of the Rich Agreement Hypothesis, which is predicated on the claim that (a)–(c) are universally obligatory. The facts necessitate revision of Koeneman and Zeijlstra’s proposal.

The semantic basis and morphosyntactic reflexes of Kiowa-Tanoan noun classification are perspicuously captured in a system with three bivalent number features: [±singular], [±augmented], [±group]. Privative analyses of the same facts require, inter alia, features without semantic motivation, syntactic mechanisms that violate Inclusivity, and feature annotation reminiscent of bivalence. The semantic atoms of number are, therefore, bivalent.