Fallacy of the Four Terms


Treo Compatable Fallacies list

(quaternio terminorum)


Definition:

A standard form categorical syllogism contains four terms.

Examples:

(i) 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:

(ii) 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.

Proof:

Identify the four terms and where necessary state the meaning of each term.