The fallacy is committed when a standard form categorical syllogism contains four terms.
- "All dogs are animals, and all cats are mammals, so all dogs are mammals." The four terms are: dogs, animals, cats and mammals. Note: In many cases, the fallacy of four terms is a special case of equivocation. While the same word is used, the word has different meanings, and hence the word is treated as two different terms. Consider the following example:
- "Only man is born free, and no women are men, therefore, no women are born free." The four terms are: man (in the sense of 'humanity'), man (in the sense of 'male'), women and born free.