This paper discusses the semantically parenthetical use of clause-embedding verbs such as see, hear, think, believe, discover and know. When embedding verbs are used in this way, the embedded clause carries the main point of the utterance, while the main clause serves some discourse function. Frequently, this function is evidential, with the parenthetical verb carrying information about the source and reliability of the embedded claim, or about the speaker's emotional orientation to it. Other functions of parenthetical uses of verbs are discussed. Particular attention is paid to the parenthetical uses of verbs which are standardly assumed to require their complements to be presupposed. It is demonstrated that when so used, these verbs are in no way presuppositional; that is, there is no presumption, or even pretense, that their complements have common ground status. It is further demonstrated that this loss of presuppositionality is not accompanied by a lack of commitment on the part of the speaker to the truth of the complement, as in the standard cases of non-presuppositional uses of these predicates. It is argued that this non-presuppositional use of factive verbs provides support for the (minority) view that presupposition is not a conventional property of lexical items. [Copyright &y& Elsevier]