Ambiguity

Core claim: An argument is invalid or misleading because a term, phrase, or statement has more than one meaning and this ambiguity is not resolved.

• The same word or expression is used in two (or more) different senses within the same argument, without this being made explicit.
• A conclusion depends on a particular reading of an ambiguous statement that is not justified by context.
• None of the more specific forms of ambiguity (etymological fallacy, motte-and-bailey, generic generalization, intensional fallacy) apply precisely, but the reasoning still hinges on an unresolved ambiguity.

• This entry serves as a fallback for ambiguities that do not fit neatly into one of the sub-categories. If a more specific pattern matches, prefer that classification.
• Ambiguity is often hardest to spot when both senses of a term are plausible in context – the argument then appears coherent on first reading while silently shifting meaning.

• The ambiguity is acknowledged and both readings are considered explicitly.
• A term has multiple meanings but is used consistently in only one sense throughout the argument.
• Context makes the intended meaning unambiguous (e.g., domain-specific terminology whose meaning is clear from the situation).

• Equivocation (MD) – equivocation is the act of shifting meanings; ambiguity is the broader category that includes it. Ask: am I flagging the mechanism (→ equivocation) or the general pattern (→ ambiguity)?
• Four-term fallacy (MD) – a syllogism with four terms is often caused by ambiguity, but the formal error is the extra term. Ask: is the problem the invalid syllogistic form (→ four-term) or the ambiguous wording that produced it (→ ambiguity)?
• Etymological fallacy (MD) – applies only when an argument appeals to a word's original/historical meaning. If the ambiguity is not etymology-based, use this entry instead.

Input: “Nothing light can ever be dark. All feathers are light. Therefore: no feather can be dark.”
Output: The term “light” shifts meaning between premises (weight vs. brightness). Disambiguate the term before drawing a conclusion – under one reading the argument is true but trivial, under the other it is false.

Input: “Humans is a species. Socrates is a human. Therefore: Socrates is a species.”
Output: “Humans” refers to the collective in the first premise and to individual members in the second. The conclusion only follows if the same sense is used throughout.

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