The Undistributed middle is a fallacy similar to to Equivocation, except that instead of conflating definitions, two different things are equated due to a common middle ground that is misused. The argument is assuming that the set of Object-A that has the middle ground intersects with the set of Object-B that has the same middle ground.
- Example 1
- All cats use air.
- All gasoline engines use air.
- Therefore, all cats are gasoline engines.
- Example 2
- Example 3
- All fish live in water.
- All whales live in water.
- Therefore, all whales are fish (They're not - they're mammals)