Final answer:
Bitzer's theory focuses on the rhetorical situation, while Grant-Davie extends it by introducing the concept of the rhetorical audience.
Step-by-step explanation:
Bitzer's Theory and Grant-Davie's Extension
Bitzer's theory, originally proposed by Lloyd Bitzer, focuses on the concept of the rhetorical situation. It argues that the effectiveness of a speech or piece of writing is determined by the fit between the speaker's purpose, the audience, and the constraints of the situation.
Grant-Davie extends Bitzer's theory by introducing the concept of the rhetorical audience. While Bitzer emphasizes the role of the situation, Grant-Davie suggests that audience interpretation and response are crucial to understanding rhetoric. Grant-Davie's extension broadens the scope of Bitzer's theory and highlights the dynamic relationship between the speaker and the audience.