Difficulty: Easy
Correct Answer: Only I and II follow
Explanation:
Introduction / Context:
This item combines universal inclusion (“all balls are bats”) with existential overlaps (“some saints/tigers are balls”). The goal is to propagate membership through the universal set while testing which categorical conversions are valid.
Given Data / Assumptions:
Concept / Approach:
If a particular element lies in “balls,” and “all balls are bats,” then that element automatically lies in “bats.” Therefore, any “some … are balls” statement converts into “some … are bats.” Conversely, “all bats are balls” is not supported by “all balls are bats” (that would be the illicit converse of a universal statement).
Step-by-Step Solution:
I. Some bats are tigers: Since some tigers are balls and every ball is a bat, those same tigers are bats. Hence I follows.II. Some saints are bats: Since some saints are balls and all balls are bats, those same saints are bats. Hence II follows.III. All bats are balls: The given universal is one-way (balls ⊆ bats). It does not establish the reverse (bats ⊆ balls). III does not follow.
Verification / Alternative check:
Imagine bats include many things besides balls; the premises remain true while III fails. I and II must hold due to direct subset propagation from B to Bt.
Why Other Options Are Wrong:
Common Pitfalls:
Conflating “all A are B” with “all B are A”; forgetting that “some A are B” can be pushed through a universal inclusion.
Final Answer:
Only I and II follow
Discussion & Comments