IBPS Clerk · Bite-size lessons
Syllogism
About 6 min · Reasoning Ability · English
Time worked out from the lesson's 428 words at 150 words a minute, plus a minute for each question.
Syllogism is one of the most predictable and scoring topics in the IBPS Clerk Reasoning section. Each set presents two statements followed by conclusions, and you must determine which conclusions logically follow.
Key ideas
- Statements establish relationships between two groups using quantifiers. Think of each group as a circle, and the quantifier tells you how these circles overlap.
- Four standard quantifiers exist: All (complete inclusion), Some (partial overlap), No (complete exclusion), and Some not (partial exclusion).
- "All A are B" does not mean "All B are A." Direction matters—if all dogs are animals, it doesn't mean all animals are dogs.
- "Some" implies at least one, possibly all. When a statement says "Some A are B," it means one or more A could be B, including the possibility that all A are B.
- "No" is a complete denial and works both ways. "No A is B" automatically means "No B is A."
Watch out for
- Reversing "All" statements incorrectly → "All A are B" does NOT mean "All B are A." Only convert to "Some B are A."
- Treating "Some" as "Only Some" → "Some A are B" includes the possibility that all A are B. Don't assume some are excluded.
- Ignoring the "Some not" dead-end → "Some A are not B" cannot be converted, and gives a conclusion only in a few cases (e.g., Some A are not B + All C are B → Some A are not C). Don't force conclusions from it.
Quick reference
- All + All = All; All + No = No; Some + All = Some; Some + No = Some not.
- "No" is reversible; "All" converts to "Some" (reversed); "Some not" has no valid conversion.
- Draw Venn diagrams for accuracy—speed comes with practice.
- Either-Or applies when conclusions are a complementary pair and neither follows alone.
- Some = At least one, possibly all. Never assume exclusion.
Check yourself: 3 questions
1. Statements: All pens are pencils. All pencils are erasers. Conclusions: I. All pens are erasers. II. Some erasers are pens.
2. Statements: Some books are novels. No novel is a magazine. Conclusions: I. Some books are not magazines. II. No book is a magazine.
3. Statements: All chairs are tables. Some tables are desks. Conclusions: I. Some chairs are desks. II. Some desks are chairs.
This lesson is cut from the topic's note, not rewritten. Fact-checked on 17 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.
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