No. 26 Fallacies of Ambiguity
Equivocation
In Turkish: Cinaslı Safsata
One word, two meanings, one sentence. I noticed the switch.
The doctor told you two litres of water a day, Dursun.
Tea’s water, isn’t it? Ten glasses a day, I’m well over.
Olive oil’s a liquid too, Dursun. The doctor didn’t say “liquid”, he said “water”.
What is it?
Using a word in one sense at the start of an argument and another sense at the end. The argument looks sound because the word stays the same; it’s broken because the meaning doesn’t.
The pattern
- X is A. (first sense of X)
- Whatever is A is B.
- Therefore X is B. (second sense of X)
Why it fails
Language is elastic: “water” is both the thing you drink and a loose word for any liquid. The brain sees the word, fills in a meaning, and treats two meanings as one. That’s why a pun makes a joke funny and an argument crooked: the person taken in doesn’t notice the word changed; they think they were convinced.
How to spot it
- The argument’s key word does two different jobs in two sentences.
- Swap the word for a synonym and the argument collapses.
- The conclusion says something bigger than the premises did.
What to say
Nail the word down: “What exactly do you mean by water? Use the same meaning in the second sentence.” Once the meaning is fixed, the argument either stands or falls apart on its own.
When it’s not a fallacy
Wordplay, jokes and poetry aren’t fallacies; nobody is being persuaded of anything. Neither is talking about a word’s two meanings while clearly distinguishing them. The fallacy is drawing a conclusion while the shift in meaning goes unnoticed.
Examples
- AdsA “light” drink: light in calories, in taste, or in the bottle? The ad doesn’t choose; you do.
- Work“Flexible hours” was said; it sounded like come when you like, it meant work when we like.
- SchoolThe “natural” in “natural number” isn’t the “natural” in “natural product”; mix them up in an exam and the teacher laughs.
- Family“I gave you my word,” he said; the “word” he gave was a sentence, not a commitment.