The central idea is an important concept to master in order to deliver effective public speeches. However, it does take work to understand and write great central ideas. After you have identified your objectives: the general purpose and specific purpose statement, it is time then to write a central idea.
According to "Public Speaking for College and Career" by Hamilton Gregory, the central idea is the key concept of a speech. Stephen Lucas fleshes out the concept even more in "The Art of Public Speaking." Lucas adds that the “central idea further refines and sharpens the specific purpose statement.” He also includes that the central idea encapsulates the main points to be developed in the body of the speech.
Regardless of which definition you use, the premise is the same. The central idea controls the speech—it is like the steering wheel of a car. From the central idea the audience should be able to predict what is and is not going to be covered in a speech. There are some specific guidelines for writing a central idea:
- The central idea should we written as one complete sentence.
- The central idea should be an assertion and written as a declarative sentence.
- The central idea should avoid figurative language.
- The central idea should not be vague or general.
For example:
Topic: popcorn
General Purpose: to inform
Specific Purpose: To inform my audience about popcorn.
Central Idea: The two most common methods of serving popcorn are salted or sweetened.
In this example, we can predict that this speech will have two main points: Serving popcorn in a salted application and serving popcorn as a sweet snack. We would not expect to hear anything about other uses of popcorn—such as decoration or packing material.
Each speech can only have one central idea, but there are numerous central ideas that can be written for any one specific purpose. Say, for example, that we wanted to talk about the various uses for popcorn. In that case, we might write this for the central idea:
Popcorn can be enjoyed as a snack, household decoration, or even as packing material.
In this speech, we would expect to hear about popcorn being used as decoration and as an inexpensive packing material. It is also logical to assume that as a sub-point we might hear information on the different types of popcorn snacks—salty and sweet.
Neither of these central ideas takes into account the history of popcorn or how to prepare popcorn. If you wanted to speak about those points you would need to write a different central idea. Perhaps this one:
Popcorn has an interesting history that has led to a variety of preparation methods and uses.
This central idea tells us that the speech is going to include information about the history of popcorn, the preparation methods, and other uses besides food.
Writing the central idea takes the specific purpose and adds the main points. It can be reduced to the following mathematical equation:
specific purpose statement + main points = central idea
As you can see, the central idea really is the driving force of the speech. Combined with the general purpose and specific purpose these three objectives will set you up to prepare an interesting speech. After defining your objectives you are ready to start outlining the body of your speech!
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