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8. Informal Fallacies - Ambiguity

 

Summary​

The first and smallest family of informal fallacies is the fallacies of ambiguity: errors caused by the unclear meaning of words, phrases, or grammar. The fallacy occurs when the meaning of a term shifts during the argument and the conclusion depends on that shift. These are essentially problems of language, and many overlap with the rhetorical devices seen earlier. There are six.

1. Equivocation​

A key word carries more than one meaning and changes sense between premises, blocking the conclusion (the formal counterpart is the four-term fallacy). It is the serious cousin of the pun (as in Abbott and Costello's Who's on First?, where one speaker uses a word as a question and the other as a name). Examples:

  • "An elephant is an animal, therefore a small elephant is a small animal", small is a relative term.
  • "All good things should be legal; feeling good is good; beating up people you dislike feels good; therefore it should be legal", good shifts from morally good to pleasurable.
  • Arguing from micro- to macro-evolution, or a theological argument where really means "truly" in one premise but "in mutual dependence" (Aquinas's sense) in another.

(Note: refuting such an argument does not disprove its conclusion, only this way of reaching it.)

2. Amphibology​

Ambiguity from grammatical construction rather than a single word. The premise is read in a way that makes it true, but the conclusion is drawn from a reading that makes it false:

  • "Reverend Smith said it was his privilege to marry six people yesterday."
  • "Wife kills husband with shotgun" (her weapon, or his?).
  • "Our burgers are made with 100% pure beef" (entirely beef, or just one ingredient?).

3. Accent​

Improper emphasis on a word or part of a statement (via punctuation in writing or inflection in speech) changes the meaning between premise and conclusion:

  • "Shake well before using", so I shook it after breakfast.
  • "I'm not taking you to the movies" vs. "I'm not taking you to the movies", different implications, and the "we'll be home tonight" conclusion may be false.

4. Significance​

Language whose meaning depends on its referent or context:

  • A voicemail, "your father has been rushed to the hospital", is meaningless if it was a wrong number (who is "your"?).
  • "Hesiod talked about the creation of the world, so he was a theist", but he wrote from a polytheistic worldview.

5. Distinction without a difference​

Defending a position by claiming a difference from another that does not actually exist, different words for the same concept:

  • A changed phone number vs. a new number (Seinfeld).
  • "There's no good or evil, only functional and dysfunctional", but dysfunctional presupposes a correct way to function, which is itself a moral standard.

6. Prestige jargon​

Using complicated or technical language to sound smart or scientific and silence opposition, a smoke screen that confuses complexity with authenticity. (It is not always a fallacy, since some topics genuinely require technical vocabulary.) Examples include deliberately obscure, pseudo-scientific verbiage about "axiomatic conclusions concerning metaphysical hypotheses."

Practice​

This only scratches the surface: the best approach is to review the examples and practice spotting ambiguity yourself. Next comes the much larger family, the fallacies of relevance.