Logic from Sheridan Baker,

The Practical Stylist

A "logical fallacy" is an error of logic. Sometimes they're honest errors, but sometimes advertisers and politicians use them deliberately to persuade us to buy or vote without thinking through the decision. Learning the following patterns of faulty logic will help you avoid being swept up in faulty reasoning.
The exercises below make a good start: they use the fallacies listed here.

List of Logical Fallacies

1. Either-Or. You assume only two opposing possibilities: "either we abolish requirements or education is finished." Education will probably amble on, somewhere in between.

2. Oversimplification. As with either-or, you ignore alternatives. "A student learns only what he wants to learn" ignores all the pressures from parents and society, which in fact account for a good deal of learning.

3. Begging the Question. A somewhat unhandy term: You assume as proved something that really needs proving. "Free all political prisoners" assumes that none of those concerned has committed an actual crime.

4. Ignoring the Question. The question of whether it is right for a neighborhood to organize against a newcomer shifts to land values and taxes.

5. Non Sequitur. ("It does not follow.") "He's certainly sincere: he must be right." "He's the most popular fellow: he should be president." The conclusions do not reasonably follow from sincerity and popularity.

6. Post Hoc, Ergo Propter Hoc. ("After this, therefore because of this." ) The non sequitur of events: "He stayed up late and therefore won the race." He probably won in spite of late hours, and for other reasons.

7. False analogy. "You should choose your wife as you would your car." A person is not a machine, so that the analogy is unacceptable.
(pp. 50-51)


After each of the following assertions, write two or three short questions that will challenge its assumptions, questions like "Good for what? Throwing? Fertilizer? For example: Girls are brighter than boys. "At what age? In chess? In physics?

1. Men are superior to women.

2. The backfield made some mistakes.

3. Communism means violent repression.

4. Don't trust anyone over thirty.

5. All men are equal.

6. The big companies are ruining the environment.

7. Travel is educational.

8. Our brand is free of tar.

9. The right will prevail.

10. A long walk is good for you.

Name and explain the fallacy in each of the following:

1. Jones is rich. He must be dishonest.

2. He either worked hard for his money, or he is just plain lucky.

3. The best things in life are free, like free love.

4. Sunshine breeds flies, because when the sun shines the flies are out.

5. If they have no bread, let them eat cake. Cake is both tastier and richer in calories.

6. This is another example of American imperialism.

7. Smith's canned soup empire reaches farther than the Roman empire.

8. Chips is America's most popular soup. It clearly is the best.

9. The draft is illegal. It takes young men away from their education and careers at the most crucial period of their lives. They lose thousands of dollars' worth of their time.

11. Women are the most exploited people in the history of the world.

11. Two minutes after the accused left the building, the bomb exploded.

12. The human mind is only an elaborate computer, because both can do complex calculations and make decisions.
(pp. 53-54)