Difficulty: Easy
Correct Answer: Only (1), (3) and (4)
Explanation:
Introduction / Context:
This is a standard three-set syllogism with nested universals. We must derive all conclusions that must be true from the chain goats ⊆ tigers ⊆ lions.
Given Data / Assumptions:
Concept / Approach:
Transitivity: if A ⊆ B and B ⊆ C, then A ⊆ C. From “All A are C” and existence of A, we may also infer “Some C are A” and, since A ⊆ B, “Some B are A”.
Step-by-Step Solution:
(1) All goats are lions — true by transitivity (A ⊆ C). (2) All lions are goats — converse of (1); not supported. (3) Some lions are goats — since goats exist and every goat is a lion, at least some lions are goats. (4) Some tigers are goats — every goat is a tiger; existence of goats guarantees some tigers are goats.
Verification / Alternative check:
Venn diagram with three nested circles immediately shows (1), (3), and (4) as necessary; (2) is not forced and is generally false unless all lions happen to be goats.
Why Other Options Are Wrong:
Any option including (2) assumes an unjustified converse.
Common Pitfalls:
Confusing subset relations with equality and overlooking the existence requirement for “Some …” conclusions.
Final Answer:
Only (1), (3) and (4)
Discussion & Comments