6. Classify the pupils in your school.
7. Classify the people in your school. Is there any difference?
8. Classify the following:
The political parties of the country.
Methods of transportation.
Religions.
Magazines.
The buildings in a city.
Aircraft.
Desserts.
Canned goods.
Skill in division is valuable not only as a method of exposition but it is linked closely with an effective method of proving to be explained in the next chapter—the method of residues. Can you recall any extracts given in this book in which some form of division is used? Is this form of material likely to be more important in preparation or in the finished speech? Explain your opinion—in other words, present a specimen of exposition.
Definition. One of the simplest ways of explaining is to define a term. Dictionary definitions are familiar to everyone. In a great many instances the dictionary definition is by means of synonyms. While this is a convenient, easy method it is seldom exact. Why? Recall what you learned concerning the meanings of synonyms. Do they ever exactly reproduce one another's meanings? There is always a slight degree of inaccuracy in definition by synonym, sometimes a large margin of inexactness. Is the following a good definition?
A visitor to a school began his address: "This morning, children, I propose to offer you an epitome of the life of St. Paul. It may be perhaps that there are among you some too young to grasp the meaning of the word epitome. Epitome, children, is in its signification synonymous with synopsis!"
London Tid-Bits
Logical Definition. An exact definition is supplied by the logical definition. In this there are three parts—the term to be defined, the class (or genus) to which it belongs, and the distinguishing characteristics (differentia) which mark it off from all the other members of that same class. You can represent this graphically by inclosing the word term in a small circle. Around this draw a larger circle in which you write the word class. Now what divides the term from the class in which it belongs? Indicate the line around the term as distinguishing characteristics, and you will clearly see how accurate a logical definition is. The class should be just larger than the term itself. The main difficulty is in finding exact and satisfying distinguishing characteristics. There are some terms which are so large that no classes can be found for them. Others cannot be marked by acceptable distinguishing characteristics, so it is not possible to make logical definitions for all terms. Consider such words as infinity, electricity, gravity, man.