The aim of this paper is to offer a qualitative analysis of the relationship between disagreement, epistemic stance and contrast in parliamentary debate. To this end, all disagreeing moves including both an epistemic stance marker and a contrastive marker equivalent to but have been identified in a corpus of parliamentary debates in Catalan. The epistemic stance markers have been classified considering three main factors: type of marker (epistemic, evidential, attitudinal), epistemic scale (certainty-uncertainty) and position (either in the thesis or in the antithesis). The approach adopted encompasses interactional linguistics and pragmalinguistics as it considers how context variables, such as those related to genre, have an influence on the use and discourse effects of markers of epistemic stance and contrast. The main research questions are two: (i) how genre norms have an incidence on the expression of disagreement and the interpretation of epistemic stance markers, and (ii) how epistemicity and contrast interact with disagreement in parliamentary debate in order to reinforce the speakers' argumentation and block the opponent's opinion, as either questionable or shared knowledge. The analysis shows that disagreeing moves in the corpus establish a long-distance relation with a previous stretch of discourse and trigger a polyphonic strategy that can be expressed through a contrastive construction where epistemic markers qualify either the thesis or the antithesis. In both cases, the disagreeing argument (i.e. the antithesis) is thus reinforced not only when the epistemic stance marker expresses certainty but also when it expresses uncertainty.