| Mood and Figure: OOO-2 | Some P are not M Some S are not M Some S are not P |
| rule | rule met? | explanation | |
| 1. | If a syllogism is valid, then the middle term is distributed at least once. | yes | Middle term is distributed in both premises. |
| 2. | If a syllogism is valid, then if a term is distributed in
the conclusion, it must be distributed in a premise.
|
no | "P" is distributed in the conclusion, But not in the premise. |
| 3. | If a syllogism is valid, it does not have two negative
premises.
|
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| 4. | If a syllogism is valid, then it has a negative premise, if
and only if it has a negative conlusion.
|
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| 5. | If a syllogism is valid, then if its premises are universal,
then its conclusion is universal.
|
Result: This argument is invalid, because rule 3 is violated. We stopped checking rules as soon as we found one rule violated.