This paper proposes mechanisms for agents to model other agents' beliefs and arguments, thus enabling agents to anticipate their interlocutors' arguments in dialogues, which in turn facilitates strategising and the use of enthymemes. In contrast with existing works on “opponent modelling” that treat arguments as abstract entities, the likelihood that an interlocutor can construct an argument is derived from the likelihoods that it possesses the beliefs required to construct the argument. We therefore address how a modelling agent can quantify the certainty that its interlocutor possesses beliefs, based on the modeller's previous dialogues, and the membership of its interlocutor in communities.