The undistributed middle fallacy occurs when the middle term is not distributed at least once, so it fails to connect the other terms.
Example
“All A are C.
All B are C.
Therefore, all A are B.”
(C does not connect A with B.)
Applied example (political)
“All patriots respect the flag.
All voters of party X respect the flag.
Therefore, all patriots vote for party X.”
(Sharing a symbol does not imply identity.)
Why it is fallacious
- The middle term fails to link the categories.
- The conclusion does not follow from the premises.
- Shared membership is mistaken for identity.
How to spot it
- The middle term appears only as an undistributed predicate.
- A and B are linked only by sharing C.
- The conclusion is stronger than justified.
How to respond
- Ask for a premise that distributes the middle term.
- Show that sharing a property does not imply identity.
- Offer a simple counterexample.