Syllogism (Categorical Logic) — Determine which conclusions logically follow from the statements Statements: • Some bricks are trees. • All trees are pens. • All pens are boats. Conclusions: I. Some boats are bricks. II. Some pens are bricks. III. Some trees are bricks. IV. Some bricks are boats.
-
AOnly I and II follow
-
BOnly III and IV follow
-
CNone follows
-
DAll follow
-
ENone of these
Answer
Correct Answer: All follow
Explanation
Introduction / Context:This verbal reasoning problem tests categorical syllogism skills. You are given three premises about class inclusion and intersection (Some / All) and asked which among four “Some …” conclusions necessarily follow. The key is to map class relationships and remember valid conversions for particular statements.
Given Data / Assumptions:
- Premise 1: Some bricks are trees (there exists at least one object that is both a brick and a tree).
- Premise 2: All trees are pens (Trees ⊆ Pens).
- Premise 3: All pens are boats (Pens ⊆ Boats).
- Conclusions to test: I, II, III, IV as listed in the stem.
Concept / Approach:Use transitivity of “All” (subset) and the fact that “Some S are P” is convertible to “Some P are S.” Also, when a particular element is inside a subset chain, it propagates through the chain (membership inheritance).
Step-by-Step Solution:
From Premise 1 and 2: Some bricks are trees, and all trees are pens ⇒ those same bricks are pens ⇒ Some pens are bricks (Conclusion II).From 1, 2, and 3: Those bricks are trees and pens; since all pens are boats ⇒ those bricks are boats ⇒ Some bricks are boats (Conclusion IV).Convert IV: “Some bricks are boats” implies “Some boats are bricks” by valid conversion of a particular proposition ⇒ Conclusion I follows.Convert Premise 1: “Some bricks are trees” implies “Some trees are bricks” ⇒ Conclusion III follows.Verification / Alternative check:Construct a minimal Venn model: Put at least one element simultaneously in Brick, Tree, Pen, Boat (due to subset chain Tree ⊆ Pen ⊆ Boat). All four conclusions are witnessed by that single element and valid conversions.
Why Other Options Are Wrong:
- “Only I and II”, “Only III and IV”: both miss additional valid conclusions.
- “None follows”: contradicted by the direct derivations above.
- “None of these”: not needed because “All follow” is correct.
Common Pitfalls:Forgetting that “Some S are P” converts to “Some P are S,” and failing to propagate membership through a chain of universal inclusions (“All” statements).
Final Answer:All follow