Modes of discourse, also known as rhetorical modes, are concepts that describe the different purposes of communication and genres of composition. How an author or speaker approaches a particular work, frames the presentation of it, and outlines what to include depends on the desired response of the audience. The desired response dictates which mode of discourse, or formalized approach to presenting an idea, is most appropriate.
Most often, the term "modes of discourse" is used to describe types of essays or other written works. When studying composition, especially regarding English composition and English literature, educators teach four major discursive modes, classified as exposition, narrative, description, and argument. While theses genre labels are generally applied to written works, the concepts also apply to spoken communication.
Expository and argumentative modes of discourse are very similar. Primarily, the differences between exposition and argument lie in the amount of preparation required. Typically, an argumentative work requires more research and empirical evidence than an expository work. Both modes involve investigating a topic, reviewing and evaluating available information, then presenting a clear view or argument regarding the topic. Authors and speakers typically use exposition or argument to persuade an audience for or against a particular point of view.
Narrative essays and similar forms of communication involve more storytelling than expository or argumentative works. In terms of modes of discourse, a narrative approach allows for more creativity, relying less on research and more on the audience's ability to relate to the writer or speaker. Rather than facts, figures, and evidence, narration allows the creator to provide personal insight, stories, and other experiential or anecdotal examples to persuade an audience.
Descriptive works cover a broad range of topics. An essay discussing the architecture of the Sistine Chapel, for instance, would be an example of a descriptive work. Like narratives, descriptive works allow for more creativity than other modes. Unlike a narrative, descriptive works do not have to present personal insight. Instead, descriptive works provide a clear, vivid mental image for the audience, relying on the audience's own personal insight, knowledge, and emotions to evoke certain responses.
Within each of the four major modes of discourse, a speaker or an author furthers the purpose of spoken or written communication with specific rhetorical approaches. For example, an expository essay might employ such methods as compare and contrast, examples and case studies, or cause and effect. Similarly, an argumentative or persuasive speech might employ classification and division. Effective use of rhetorical approaches within the bounds of a particular mode of discourse helps further an author's or speaker’s intended goal.