Lesson · 4 min Gentle

One Word, Two Meanings

In one line An argument can slide between two senses of a word, and the conclusion only works in one.

Equivocation uses one word in two senses within an argument. A classic case: “A feather is light. What is light cannot be dark. So a feather cannot be dark.” The word “light” means not heavy in one line and not dark in another. The argument looks valid, but it is not.

In real talk the slide is subtler. “Being tough on crime protects neighbors. Our plan is tough on crime. So our plan protects neighbors.” “Tough” means effective action in the first line and severe punishment in the second.

To catch it, underline the key words and restate each claim with the word’s meaning spelled out. If the argument falls apart, it relied on the slide.

A free voice

At a club meeting, Hana argues, “Everyone deserves a free voice. Our newsletter gives everyone a free voice. So it should be free of charge.”

Lou notices the word “free.” In the first line it means unrestricted speech, and in the last it means no cost. He restates: the newsletter’s speech can be open without being priced at zero. The argument had used one word for two ideas.

Try this today Pick a key word in an argument you are reading and ask if it means the same thing each time.