Statements: All trucks fly. Some scooters fly. Conclusions: I. All trucks are…
2024
Statements: All trucks fly. Some scooters fly.
Conclusions:
I. All trucks are scooters.
II. Some scooters do not fly.
- A.
Only conclusion I follows
- B.
Either I or II follows
- C.
Only conclusion II follows
- D.
Neither I nor II follows
Attempted by 3 students.
Show answer & explanation
Correct answer: D
Concept
In a categorical syllogism, a conclusion linking the two end terms is valid only if the middle term (the term common to both premises) is distributed — refers to its entire class — in at least one premise. Separately, two affirmative premises can only yield an affirmative conclusion; they can never yield a negative one.
Application
Premise 1, "All trucks fly", is a universal affirmative (A-type) statement: it distributes only its subject "trucks", not its predicate "fly".
Premise 2, "Some scooters fly", is a particular affirmative (I-type) statement: it distributes neither "scooters" nor "fly".
The middle term "fly" is therefore undistributed in both premises, so no valid conclusion can connect the two end terms "trucks" and "scooters" — conclusion I fails.
Both premises are affirmative, so only an affirmative statement about scooters and flying could follow — never the negative claim in conclusion II — so conclusion II fails too.
Cross-check
Cross-check with a concrete case: let trucks and scooters be two entirely unrelated groups of things that both happen to fly (for example, if "trucks" meant one kind of flying object and "scooters" meant another, unrelated kind). Both premises stay true while trucks and scooters need not overlap at all, and scooters flying is still fully consistent with every scooter flying. This confirms neither conclusion is forced by the premises.
Result
Since the middle term is undistributed in both premises and both premises are affirmative, neither conclusion I nor conclusion II follows.