A categorical syllogism with both negative premises is invalid. Two negations do not establish a reliable relation between terms.
Example
“No feline is a reptile.
No reptile is a cat.
Therefore, no cat is a feline.”
(The conclusion does not follow.)
Applied example (political)
“No corrupt person is a patriot. No patriot is an official. Therefore no official is corrupt.” (Two negatives do not connect.)
Applied example (mystical)
“No ritual is scientific. No science is spiritual. Therefore no ritual is spiritual.” (The conclusion does not follow.)
Why it is fallacious
- There is no valid middle term connection.
- Two negative premises cannot yield a solid conclusion.
- A conclusion is created without a logical bridge.
How to spot it
- Both premises are negative (“no”, “none”).
- The conclusion denies something without support.
- No affirmative link between categories.
How to respond
- Point out that the premises do not connect.
- Ask for an affirmative middle term.
- Reformulate with premises that allow a valid inference.