Equivocation (from Latin aequus, “equal,” and vox, “voice,” “word”) is a logical fallacy in which the same word or expression is used with different meanings within a single argument, creating the appearance of a valid conclusion.
In Brief
Equivocation occurs when:
1. a term is introduced with one meaning;
2. it is then imperceptibly replaced by a different meaning;
3. the conclusion is drawn as though its meaning had not changed.
As a result, an argument may look logical even though it actually relies on a substitution of meaning.
A Simple Example
- “Only a human being has the right to vote.”
- “Peter has the right to make decisions on the team.”
- “Therefore, Peter has a voice as a biological characteristic that distinguishes a human being.”
The word “right” in (1) and (2) belongs to different contexts, while the conclusion conflates levels of meaning.
Where It Occurs Most Often
- in public polemics;
- in political rhetoric;
- in advertising and ideological formulations;
- in disputes where the definitions of key terms have not been established.
How to Recognize and Avoid It
- Explicitly establish the meaning of key words at the beginning of a discussion.
- Check whether a term’s meaning changes between the premises and the conclusion.
- Distinguish homonymy (one word, different meanings) from precisely defined terms.
- Reformulate the argument so that each meaning is represented by a separate term.
Practical Formula
If an argument “holds together” only while a word remains ambiguous, this is a strong sign of equivocation.
