In (31), there is no antecedent for the open proposition that ‘‘people thought something about theNorth in 1967’’. In (32), the open proposition that ‘‘dentists get a bit overwhelmed for somereason’’ is indeterminate as between new and inferrable: there has been no prior mention in theconversation of dentists becoming overwhelmed by their circumstances, and yet the discussion ofthe pressures currently confronting them in England makes the proposition at least assumable tosome extent. In both cases there is tension between the informational newness of the openproposition on the one hand, and its non-negotiability as a presupposed proposition on the other.