The article explores presupposition projection in attitude verbs, focusing on how presuppositions are projected in propositional attitude sentences. Irene Heim argues that when the complement of an attitude sentence presupposes a proposition, the entire sentence presupposes that the attitude-holder believes that proposition. This is derived from assumptions about the lexical semantics of attitude predicates within a context change semantics framework, which incorporates Stalnaker's view that presupposition projection arises from the stepwise updating of information in response to complex utterances. Heim examines the semantics of verbs of belief and desire, particularly how counterfactual mood contributes to presupposition projection. She analyzes how presuppositions are handled in sentences involving belief and desire, showing that the projection of presuppositions depends on the context and the beliefs of the subject. For example, the sentence "Patrick wants to sell his cello" presupposes that Patrick believes he owns a cello, not that he actually does. This is because the presupposition is tied to the belief of the subject, not the actual state of affairs. Heim also discusses the difference between belief and desire verbs, noting that while belief reports project presuppositions based on the subject's beliefs, desire reports may filter out presuppositions depending on the context. She introduces a conditional semantics for desire verbs, where the truth of a desire sentence depends on the desirability of possible worlds relative to the subject's beliefs. This approach helps explain how presuppositions are handled in complex sentences involving desire, such as "John believes that Mary is here, and he believes that Susan is here too," which as a whole presupposes nothing. The article also addresses the challenge of preserving the distinction between presupposition projection and filtering, particularly in cases where the content of the complement sentence might seem to imply a presupposition. Heim proposes that the context change framework can account for these phenomena by considering the interaction between the subject's beliefs and the context in which the sentence is uttered. This framework allows for a more nuanced understanding of how presuppositions are projected and filtered in attitude reports, highlighting the role of context and belief in determining the meaning of such sentences.The article explores presupposition projection in attitude verbs, focusing on how presuppositions are projected in propositional attitude sentences. Irene Heim argues that when the complement of an attitude sentence presupposes a proposition, the entire sentence presupposes that the attitude-holder believes that proposition. This is derived from assumptions about the lexical semantics of attitude predicates within a context change semantics framework, which incorporates Stalnaker's view that presupposition projection arises from the stepwise updating of information in response to complex utterances. Heim examines the semantics of verbs of belief and desire, particularly how counterfactual mood contributes to presupposition projection. She analyzes how presuppositions are handled in sentences involving belief and desire, showing that the projection of presuppositions depends on the context and the beliefs of the subject. For example, the sentence "Patrick wants to sell his cello" presupposes that Patrick believes he owns a cello, not that he actually does. This is because the presupposition is tied to the belief of the subject, not the actual state of affairs. Heim also discusses the difference between belief and desire verbs, noting that while belief reports project presuppositions based on the subject's beliefs, desire reports may filter out presuppositions depending on the context. She introduces a conditional semantics for desire verbs, where the truth of a desire sentence depends on the desirability of possible worlds relative to the subject's beliefs. This approach helps explain how presuppositions are handled in complex sentences involving desire, such as "John believes that Mary is here, and he believes that Susan is here too," which as a whole presupposes nothing. The article also addresses the challenge of preserving the distinction between presupposition projection and filtering, particularly in cases where the content of the complement sentence might seem to imply a presupposition. Heim proposes that the context change framework can account for these phenomena by considering the interaction between the subject's beliefs and the context in which the sentence is uttered. This framework allows for a more nuanced understanding of how presuppositions are projected and filtered in attitude reports, highlighting the role of context and belief in determining the meaning of such sentences.