Shifting the meaning of a term mid-argument so a true premise appears to support a different conclusion.
"Nothing is better than eternal happiness; a ham sandwich is better than nothing" is the schoolroom version. The serious cases turn on words like "freedom", "natural" and "discrimination" shifting sense between premises.
In practice
- A contract defines "material" precisely in clause 3 and uses it loosely in clause 19, and the dispute is entirely about which meaning governs.
- A policy about "flexible working" means location to one side of the table and hours to the other, and both sign it.
- Further reading
- Wikipedia
- Subject
- Decision-making & Reasoning
- Essay
- The catalogue of predictable errors