B. rejects some modern, 'too liberal' interpretations of the notion 'presupposition' which make use of consequences, connotations, evaluative meaning components, and other aspects of an interlocutor's belief world. He then considers the filter concept proposed by Karttunen (1973: 'Presuppositions of compound sentences') and suggests rules for the interaction of presuppositions, entailments and assertions belonging to two disjuncts.