NABARD Grade B Reasoning Ability: Syllogism — Concept Guide + MCQs

Syllogism — Concept & Rules

Syllogism involves drawing logical conclusions from given statements using deductive reasoning. It is a compulsory topic in NABARD, IBPS, SBI, and all banking exams.

Types of Statements (Propositions)

TypeStatement FormExample
A (Universal Positive)All S are PAll dogs are animals
E (Universal Negative)No S is PNo cat is a dog
I (Particular Positive)Some S are PSome birds can fly
O (Particular Negative)Some S are not PSome men are not wise

Venn Diagram Rules & Quick Reference

A+A = A (All+All = All conclusion possible)
A+E = E (All+No = No conclusion)
E+A = O* (No+All = Some...not)
I+A = I (Some+All = Some conclusion)
I+E = O (Some+No = Some...not)
I+I = No conclusion; E+E = No conclusion
Conversion rules: A→I (All S are P → Some P are S); E→E; I→I; O cannot be converted

Complementary Pair Concept

When two conclusions form a complementary pair (I and O type: "Some X are Y" and "Some X are not Y"), at least one of them must be true. This is important when the question asks if "either I or II follows."

Common Exam Traps

  • Don't assume what is not stated — only work with given statements
  • "All A are B" does NOT mean "All B are A"
  • Possibility-based conclusions: "Some A can be B" is possible unless "No A is B" is given

Practice MCQs

Q1. All A are B. All B are C. Conclusion: All A are C.

  • A) True
  • B) False
  • C) Partially True
  • D) Cannot say

Answer: A — Syllogism chain: All A→B→C, so All A are C. True.

Q2. No X is Y. All Y are Z. Conclusion: No X is Z.

  • A) True
  • B) False
  • C) Partially True
  • D) Cannot say

Answer: B — No X is Y (E) + All Y are Z (A) = Some Z are not X (O*). We cannot conclude No X is Z. False.

Q3. Some M are N. No N is P. Conclusion: Some M are not P.

  • A) True
  • B) False
  • C) Partially True
  • D) Cannot say

Answer: A — Some M are N (I) + No N is P (E) = Some M are not P (O). True.

Q4. All cats are animals. Some animals are wild. Conclusion: Some cats are wild.

  • A) True
  • B) False
  • C) Partially True
  • D) Cannot say

Answer: B — All cats are animals + Some animals are wild → middle term 'animals' undistributed → no definite conclusion. False.

Q5. All birds fly. Penguin is a bird. Conclusion: Penguin flies.

  • A) True
  • B) False
  • C) Partially True
  • D) Cannot say

Answer: A — Valid syllogism: All birds fly + Penguin is a bird → Penguin flies. True (logically).

Q6. No glass is paper. All paper is soft. Conclusion: No glass is soft.

  • A) True
  • B) False
  • C) Partially True
  • D) Cannot say

Answer: B — E+A = O* (Some soft things are not glass). Cannot say No glass is soft. False.

Q7. Some rivers are deep. All deep things are dangerous. Conclusion: Some rivers are dangerous.

  • A) True
  • B) False
  • C) Partially True
  • D) Cannot say

Answer: A — I+A = I: Some rivers are dangerous. True.

Q8. All politicians are leaders. No leader is honest. Conclusion: No politician is honest.

  • A) True
  • B) False
  • C) Partially True
  • D) Cannot say

Answer: A — A+E = E: No politician is honest. True.

Q9. Some books are novels. Some novels are interesting. Conclusion: Some books are interesting.

  • A) True
  • B) False
  • C) Partially True
  • D) Cannot say

Answer: B — I+I = No conclusion. False.

Q10. All trains are vehicles. All vehicles are machines. No machine is alive. Conclusion: No train is alive.

  • A) True
  • B) False
  • C) Partially True
  • D) Cannot say

Answer: A — All trains→vehicles→machines + No machine is alive → No train is alive. True.