A play on words can be humorous, but it can also be a logical fallacy. Equivocation exchanges one definition of a word for another. Take the following examples:
- It's wrong for a man to beat his wife. When Mike played his wife Cheryl in a game of chess, he beat her. Therefore, what Mike did was wrong.
- The Virgin Islands are the only place in the United States that does not drive on the right side of the road. Therefore, they drive on the wrong side of the road in the Virgin Islands.
- Trains run on tracks. The tail of a wedding dress is called a train. Therefore, wedding dresses run on tracks
- Banks are places that store money. There is a snow bank at the end of my driveway. Therefore, there is money stored at the end of my driveway.
- Two wrongs don't make a right, but three rights make a left.
In each of these cases, two different meanings of a word are used.
Clearly, debates or claims don't typically contain such obvious cases of equivocation, they are usually more subtle. From about.com:
The sugar industry, for instance, once advertised its product with the claim that “Sugar is an essential component of the body . . . a key material in all sorts of metabolic processes,” neglecting the fact that it is glucose (blood sugar) not ordinary table sugar (sucrose) that is the vital nourishment.
The average person doesn't know, or doesn't often think about the fact that there are three kinds of sugar: glucose, sucrose, and fructose. It is easy to be deceived by the above claim of the sugar industry.
Next Lesson: The Bandwagon
