This paper addresses the semantics and pragmatics of singular and plural nominals in languages that manifest a binary morphological number distinction within this category. We review the main challenges such an account has to meet, and develop an analysis which treats the plural morpheme as semantically relevant, and the singular form as not contributing any number restriction on its own but acquiring one when in competition with the plural form. The competition between singular and plural nominals is grounded in bidirectional optimization over form-meaning pairs. The main conceptual advantage our proposal has over recent alternative accounts is that it respects Horn's 'division of pragmatic labor', in that it treats morphologically marked forms as semantically marked, and morphologically unmarked forms as semantically unmarked. In our account, plural forms are polysemous between an exclusive plural sense, which enforces sum reference, and an inclusive sense, which allows both atoms and sums as possible witnesses. The analysis predicts that a plural form is pragmatically appropriate only in case sum values are among the intended referents. To account for the choice between these two senses in context we invoke the Strongest Meaning Hypothesis, an independently motivated pragmatic principle. Finally, we show how the approach we develop explains some puzzling contrasts in number marking between English three/more children and Hungarian három/több gyerek ('three/more child'), a problem that has not been properly accounted for in the literature so far.