A
logical fallacy in which both
terms of a
categorical syllogism are
universal, but the
conclusion is
particular. This is a problem because some universal
categories are not
instantiated.
Example:
All big hairy monsters in my room are under the bed.
All beds in my room are in the corner.
Therefore, some big hairy monsters are in the corner of my room.
To prove the fallacy, assume the premises are true but that there are no instances of the category. For example, i checked the corner of my room. No monsters found. Note that it's still an invalid argument even if the conclusion is true!