Presuppositions and Appropriateness of Assertions In this paper I aim to compare and evaluate two theoretic approaches to pragmatic presuppositions: the Common Ground account and Propositional Context account. According to the Common Ground account proposed by Stalnaker (2002), it is appropriate to assert a sentence p that requires a presupposition q only if q is mutually believed as accepted as true and taken for granted by the interlocutors. Otherwise, Gauker (2002, 2008) claims that the ground of propositions taken for granted coincides with what he calls the objective propositional context , that is the set of objectively relevant propositional elements that speakers ought to share in order to evaluate the appropriateness of utterances so as to reach the goal of a conversation. The main purpose of my paper is to show that, according to the Propositional Context account, a theory of presupposition has to take into account a normative-objective notion of context. Secondly, I aim to develop a criticism of Gauker's point of view claiming that the Propositional Context account does not account for the number of ways in which a proposition can be taken for granted by the speakers depending on the context. Finally, I propose to integrate Gauker's account with a further condition for appropriateness of assertion which states that: in order to appropriately assert a sentence p that requires a presupposition q , speakers ought to recognize how they should justify q in a specific communicative context.