Additivity and probability

In this work, we give a new semantics to the notion of additivity as embodied by several discourse markers and particles in French: et, de plus and d’ailleurs. The common property of these different elements is the notion of independence of their arguments. We show that existing accounts of additive particles fail to do full justice to this notion of independence, and we propose a new semantics for and that captures this notion in a Bayesian fashion. We then evaluate the applicability of this analysis to de plus and d’ailleurs and show that, unlike et, these elements are strongly argumentative: they make an explicit reference to an external issue that is disputed in the current conversation.