Apr 082010

This is article number 5 in the fallacy series.

Article 1:  Logical Fallacies (a brief intro)

Article 2:  The Red Herring

Article 3:  Appeal to Ignorance

Article 4:  Weasel Words

An ambiguous word or statement is one that can have more than one meaning in a given context.  This in itself is not a fallacy.  It becomes a fallacy when one of the terms in a premise is used differently than it is used in the conclusion.  Remember a logical form of argument is a syllogism.  A syllogism is made up of two (or more) premises and a conclusion that necessarily follows from them.  Formally the conclusion must contain terms from each of the premises to be valid, and the terms in the conclusion must be used in the same way they were in the premises.   If they are not then the syllogism becomes invalid.  That would be a formal fallacy.  I am concerned here with informal fallacies.

Ambiguity becomes an informal fallacy when the speaker knows and uses the ambiguity to prove a point, because it is a fallacy of language and not form.  Once the error in language is uncovered and the speaker still maintains the argument then the argument becomes formally invalid.  In a brief example I’ll say the following.

1.  Someone who is hot needs a drink.

2.  Bill is hot!

3.  Conclusion:  Bill needs a drink because he is hot.

This is a valid and simple syllogism as far as it goes, until we find out that Bill is mad and not overheated.  In one case the argument is ambiguous and proves nothing as hot is never defined.  In the other, it is formally invalid as the true meaning of hot in one of the premises doesn’t match the meaning in the conclusion.  It’s hard to believe people would do this on purpose.  Just think back though to President Clinton and “it depends on what the meaning of is…is.”

Before we move on I would like to point out that many of the informal types of Ambiguity are also linked to formal fallacies.  I suspect this is because determining which it is depends on the honesty of the person making the argument.  Either way there is either a formal or informal fallacy involved and a conclusion can’t be properly reached.

There are a few different forms of Ambiguity.  I’m only going to cover Equivocation.  The other forms are very similar in one way or another and Equivocation is the most common in everyday discourse.


Almost all words in themselves are equivocal, having or allowing more than one meaning (voice.)  Do not mistake this for “equivalent,” (being equal.)  Many phrases are also equivocal.  When discussing things in search of the truth, we should seek to find words and phrases that are univocal, (one voice) having only one possible meaning.  This is practically impossible as most words are equivocal.

We should always know what we mean when we speak and thus we speak univocally.  The problem comes when we assume we understand the authors words the same as they meant them, but do not.  If I innocently pour different meanings into the words you speak, I am not committing a fallacy, I just misunderstand you and need clarification.  Neither party is wrong for a misunderstanding.  It’s when I attempt to force you to accept my meaning for your words that I am equivocating.

“You said you were on fire during the speech.  That’s why I threw the water on you.  I don’t know why you are mad.  You’re the one who said you were on fire.  In fact you even said you were smokin.”  Get the picture?  Even though it’s after the speech and the man was clearly not in flames, I continue to force my understanding of his words to defend my actions.

Conversely if we know our words will be taken to mean something different than our intentions, and use it anyway, we are guilty of equivocation.  Or, if we start an argument with one definition of a term and switch midstream or in conclusion we are guilty of the sub-fallacy of Redefinition.  Redefinition is a form of equivocation.

How do we avoid this?  Well,…it’s hard.  People like to use the terms they like to use and they like them defined the way they like them defined.  This can be a problem when our preferred terms and definitions don’t match.  The only thing we can do is negotiate terms and be careful to use them in ways we agree upon for sake of clarity.  Often when I try to do this I’m told I being to picky.  Later in the conversation the equivocal term comes up and it’s all down hill from there.  We have to backtrack to find out where the equivocation began.  Then we negotiate terms and try to get back on track without loosing our train of thought.  Sometimes we must start all over and sometimes it’s too frustrating for one or both so we part ways not having learned a thing.

Bottom line….Never fail to NEGOTIATE TERMS.  Stop when ambiguous language is used and clarify.  It saves so much time, confusion and aggravation.  Be patient when someone asks you to clarify what you mean by a term.

So far I’ve covered the following informal fallacies in the order given below.

  1. Informal Fallacies (a brief intro)
  2. Red Herring
  3. Appeal to Ignorance
  4. Weasel Words (a form of Red Herring)
  5. Ambiguity (this article)
  • Xbox Spiel

    I had been arguing with my close friend on this issue for quite a while, base on your ideas prove that I am right, let me show him your webpage then I am sure it must make him buy me a drink, lol, thanks.


    • Curtis

      I wish I could claim ownership of the idea here but it’s basic and much older than me. I’m interested to know what you were arguing about and how this helped? In any case, enjoy the drink!