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Syntactic ambiguity

An ambiguous wording in a statement that may lead to misunderstandings about what the statement actually says.

Consider, for example, the following syllogism:

Cars pollute the air.
All electric cars are cars.

Therefore: Electric cars pollute the air.

Although each premise appears to be true and the conclusion appears to be a correct Modus Barbara, the conclusion is obviously false.

Other names


If a statement is formulated in a way that it can be interpreted in multiple ways, this can lead to mis­con­cept­ions about the validity of the statement.

In the example above, the major clause is an amphibole of the form “𝑋 do/are 𝑌”, which can be inter­preted both distributively (i.e. as a universal statement, in the sense of “all cars pollute the air”), as well as collectively (i.e. as an existential statement, as if stated in the form: “some cars pollute the air”).

If we assume the latter (“some cars pollute the air”), the premise would clearly be true, but the syl­log­ism is then invalid, as the middle term is not distributed from an existential statement ( un­dis­tri­buted middle term). In the former case (“all cars pollute the air”), the form is correct, but the premise is then clearly false - since “all cars” would also include electric cars, which at least do not directly emit pollu­tants - and from a false premise we can’t get a true conclusion.

Note: The above example can also be interpreted in other ways, in particular:

  • The word “car” refers to different extensions in the major and in the minor premises. This leads to a four-term fallacy, or more specifically, the fallacy of the  ambiguous middle term
  • A property of a subgroup (electric cars) has been illicitly inferred from a collective property of a more general group (cars). In this particular situation, this can be interpreted as an example of the  fallacy of division
  • A general rule is applied, even though the conclusion specifically refers to a subgroup for which an exception to the rule is warranted  accident fallacy.

All of these interpretations are valid, and the example above could just as well be listed as an example in any of the linked other articles.


This fallacy is also known as the “fallacy of amphiboly”. An amphiboly is an ambiguity in the grammatical structure, which in this case leads to a fallacy of ambiguity.

Although amphibolies are also forms of equivocations, the latter term is broader and includes, above all, polysemies, i.e. words and expressions that have multiple extensions. The fallacies that result from such equivocations are described under “Four-Term Fallacy” and in related articles.

See also

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