Equivocation

Again, we have a valid argument, but this time the first premise is false, since sometimes people do desire things that they should not desire. Thus, in both cases, altering the premises to produce a valid argument produces a false premise, so the argument cannot be sound.

This is a pattern that emerges when dealing with arguments that involve the fallacy of equivocation. When the premises are interpreted in a way that produces a valid argument, then at least one of the premises is false. When the premises are interpreted in a way that makes them true, then the argu- ment is not valid. Here, then, is the strategy for dealing with arguments that may involve a fallacy of equivocation:

1. Distinguish the possible meanings of the potentially ambiguous expressions in the argument.

2. For each possible meaning, restate the argument so that each expression clearly has the same meaning in all of the premises and the conclusion.

3. Evaluate the resulting arguments separately.

If the argument fails whenever each term has a consistent meaning through- out the argument, then the argument is guilty of equivocation.

Each of the following arguments trades on an ambiguity. For each, locate the ambiguity by showing that one or more of the statements can be interpreted in different ways.

1. We shouldn’t hire Peter, because our company has a policy against hiring drug users, and I saw Peter take aspirin, which is a drug.

2. Man is the only rational animal, and no woman is a man, so women are not rational.

3. My doctor has been practicing medicine for thirty years, and practice makes perfect, so my doctor must be nearly perfect.

4. Our cereal is all natural, for there is obviously nothing supernatural about it.

5. Ice cream is never all natural, since it never appears in nature without human intervention.

6. I have a right to spend all my money on lottery tickets. Therefore, when I spend all my money on lottery tickets, I am doing the right thing.

7. You passed no one on the road; therefore, you walked faster than no one.

8. Everything must have some cause; therefore, something must be the cause of everything.

9. The apostles were twelve. Matthew was an apostle. Hence, Matthew was twelve.

10. If I have only one friend, then I cannot say that I have any number of friends. So one is not any number.