| Circular Definition | The definition includes the term being defined as a part of the definition. |
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(A circular definition is a special case of a Failure to Elucidate.)
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| Examples |
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(i) An animal is human if and only if it has human parents. (The term being defined is "human". But in order to find a human, we would need to find human parents. To find human parents we would already need to know what a human is.)
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(ii) A book is pornographic if and only if it contains pornography.
(We would need to know what pornography is in order to tell whether a book is pornographic.)
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| Proof |
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Identify the term being defined. Identify the conditions in the definition. Show that at least one term used in the conditions is the same as the term being defined.
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