Equivocation (Fallacy)

Glossary of Grammatical and Rhetorical Terms

Fallacy of equivocation
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Equivocation is a fallacy by which a key word or phrase in an argument is used with more than one meaning. Also known as semantic equivocation.

In Fallacies Arising From Ambiguity (1996), Douglas Walton observes that amphiboly "is essentially the same fallacy as equivocation, except that the ambiguity is in the grammatical structure of the whole sentence, and not just in a single term or phrase within the sentence."

In a broader sense, equivocation refers to the use of vague or unclear language, especially when the intention is to mislead or deceive an audience.

Examples and Observations

  • "The fallacy of equivocation . . . consists in this: that in the course of an argument a term changes its meaning in such a way that the conclusion seems to follow when it doesn't. Whether or not the writer is aware of the equivocation, it is still a fallacy." (Monroe C. Beardsley, Practical Logic. Prentice-Hall, 1950) 
  • "The fallacy of equivocation occurs particularly in arguments involving words that have a multiplicity of meanings, such as capitalism, government, regulation, inflation, depression, expansion, and progress ... To expose the fallacy of equivocation you give accurate and specific definitions of terms, and show carefully that in one place the definition of the terms was different from the definition in another." (Robert Huber and Alfred Snider, Influencing Through Argument. IDEA, 2005)


    "​Equivocation is a common fallacy because it often is quite hard to notice that a shift in meaning has taken place. . . . The sugar industry, for instance, once advertised its product with the claim that "Sugar is an essential component of the body . . . a key material in all sorts of metabolic processes," neglecting the fact that it is glucose (blood sugar) not ordinary table sugar (sucrose) that is the vital nourishment."

    (Howard Kahane and Nancy Cavender, Logic and Contemporary Rhetoric. Wadsworth, 1998)


    "An example of the fallacy of equivocation is found in the following brief argument, taken from a letter to the New York Times and published in 1999. The author is writing in response to an article that had described the activities of Micah White, a high school student who is an atheist and sought to lessen the influence of Christian groups in his high school. The writer, Michael Scheer, is arguing that White could not have been persecuted for his beliefs, because White is an atheist. He says:

    Micah White says he has endured 'persecution' for his beliefs, but an atheist is, by definition, one who lacks beliefs.

    In effect, Scheer is arguing:

    1. Micah White is atheist.
    2. All atheists lack beliefs.
    3. Micah White lacks beliefs.
    4. Anyone who lacks beliefs cannot be persecuted for his beliefs.
    5. Micah White cannot be persecuted for his beliefs.

    The conclusions are not explicitly stated, but they are clearly implicit...

    "The fallacy of equivocation occurs in the move from (3) and (4) to (5). In statements (2) and (3), the word beliefs must in effect mean 'religious beliefs expressing commitment to the existence of some kind of divine being.' In this sense of beliefs it is indeed true (by definition) that atheists have no beliefs.

    It will follow from the fact that White is an atheist that he lacks beliefs about supernatural beings, unless we are referring to one specific belief: that such beings do not exist. This sense of beliefs is not the one required for claim (4). The only way it can be impossible to persecute a person for his or her beliefs is for that person to have no beliefs at all. A person who does not have religious beliefs may nevertheless have beliefs on many other subjects. The sense of belief that allows (3) to be true does not allow (4) to be true. Thus, (3) and (4) cannot link as they would have to in order to support (5). The argument commits the fallacy of equivocation."

    (Trudy Govier, A Practical Study of Argument, 7th ed. Wadsworth, Cengage, 2013)

    Vagueness As Equivocation

    "Equivocation can have to do with vagueness as well as ambiguity.

    For terms in natural language, because they are intrinsically vague, may be open to varying disambiguations. Consider the following argument:

    An elephant is an animal.
    A grey elephant is a grey animal.
    Therefore, a small elephant is a small animal.

    Here we have a relative term, 'small,' that shifts meaning according to the context. A small house may not be taken, in some contexts, as anywhere near the size of a small insect. 'Small' is a highly relative term, unlike 'grey,' that shifts according to subject. A small elephant is still a relatively large animal."
    (Douglas N. Walton, Informal Fallacies: Towards a Theory of Argument Criticisms. John Benjamins, 1987)

    Climate and Weather

    "The 'warmists,' as the deniers like to call them, have been telling us for years that our rate of consumption is unsustainable and that future generations will pay a terrible price for our carelessness. If you don’t want to believe in climate change, you can argue that forecasts created by computer modeling are 'theoretical.' Or you can confuse the long-term graph of 'climate' with the short-term spikes of 'weather.' Look, there’s a snowflake! Global warming can’t be happening!

    "But acidification [of the oceans] permits no such equivocation. It is demonstrable, visible and measurable, and there is nothing theoretical about how it is caused or what it does."
    (Richard Girling, "The Toxic Sea." The Sunday Times, March 8, 2009)

    Further Reading