Equivocation (Fallacy)

Put on your critical-thinking caps

Fallacy of equivocation
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Equivocation is a fallacy by which a specific word or phrase in an argument is used with more than one meaning. It's also known as semantic equivocation. Compare this with the related term of amphiboly, where the ambiguity is in the grammatical construction of the sentence rather than just a single word or phrase. Compare also with the term polysemy, which refers to when a single word has more than one meaning, and lexical ambiguity when a word is ambiguous because it has more than one meaning.

"Equivocation is a common fallacy because it often is quite hard to notice that a shift in meaning has taken place," note authors Howard Kahane and Nancy Cavender in their book "Logic and Contemporary Rhetoric." "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" (Wadsworth, 1998).

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.

Combatting the Fallacy

You need to discover context behind the slippery terms and an argument's assertions when working to combat an equivocation fallacy.

"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," note authors Robert Huber and Alfred Snider in their book "Influencing Through Argument." "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" (IDEA, 2005).

Take a look at the following ridiculous syllogism example given in the book "Informal Fallacies: Towards a Theory of Argument Criticisms" by Douglas N. Walton:

"An elephant is an animal.
A gray elephant is a gray 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." (John Benjamins, 1987)

Investigating equivocation fallacies in a debate opponent's arguments will be more difficult than one that is readily apparent to be not factual like the above, but fallacies like this are worthwhile to combat, as getting to see behind the curtain and find truth is important, for example, when searching for people's (or politicians') motives behind what they endorse. 

Another area to dig into is vagueness of a claim or when a term is left undefined. For example, when President Bill Clinton claimed not to have "sexual relations" with Monica Lewinsky, his statement may have meant one particular act but was presented in such a way that it appeared he hoped people would infer his denial of all types of sexual contact.

Next, look also for words taken out of context from an original text or speech and twisted around to mean something other than what the person meant.