Explanation

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The basic purpose of most informative speeches is to create awareness or understanding; explanatory speeches answer the question “Why?” or “What does that mean?” Explanatory presentations delve into more complexity than demonstration speeches by providing reasons or causes and demonstrating relationships. To make your points in an explanatory speech, you must use interpretation and analysis. To this end, you should keep three main goals in mind: clarifying concepts, explaining the “big picture,” and challenging intuition.

Clarifying Concepts. If an audience’s chief difficulty rests with understanding the meaning and use of a certain term, the speaker should provide elucidating explanations—details that illuminate the concept’s meaning and use. Good elucidating explanations do three things. First, they define a concept by listing each of its critical features. For example, notice in the following sentence how the speaker provides succinct illustrations for the concept of rhetoric: “Aristotle described the canons of rhetoric as consisting of pathos (appeal to emotions), logos (appeal to logic), and ethos (appeal to character).”

Second, elucidating explanations contrast examples of the concept. For instance, a speaker might suggest that the difference between gun control and partial gun control is as distinct as night and day. Finally, elucidating examples present opportunities for audiences to distinguish between contrasting examples by looking for a concept’s critical features—for instance, demonstrating that the most important features of a golf swing are keeping the left arm straight and keeping the head still.

Explaining the Big Picture. If an idea is difficult chiefly because its complexity makes its main points—the “big picture”—hard to grasp, speakers should use a quasi-scientific explanation. Just as scientists try to develop models of the world, quasi-scientific explanations model or picture the key dimensions of some phenomenon for a typical audience. Speakers presenting complex topics to laypeople—how microchips work, the similarities and differences between levees and dams, or how DNA molecules pass along genetic information—should try to use quasi-scientific explanations. Effective quasi-scientific explanations highlight the main points with such features as titles, organizing analogies, presentation aids, and signposts (“The first key point is . . .”). Good quasi-scientific explanations also connect key points by using transitional phrases (such as “for example”), connectives (“because”), and diagrams depicting relationships among parts.

Challenging Intuition. Sometimes an idea’s chief difficulty is that it runs contrary to what intuition tells us. Consider the polio vaccine, which was tested in 1952 and used an injected dose of an inactive (essentially, dead) polio virus. The notion of using something that makes people sick to prevent people from getting sick is counterintuitive. Imagine how difficult this must have been to explain to patients and worried parents at the time.

If you are giving an informative speech on how vaccines work, you might want to design your talk around transformative explanations. Transformative explanations, which help people understand counterintuitive ideas, are designed to help speakers transform “theories” about phenomena into more accepted notions. For your speech on vaccines, you might describe how, by exposing the body to a similar but benign virus (like the dead polio virus), a vaccine essentially teaches the body to defend itself against a specific disease.