Syllogism Made Simple: The Venn Diagram Method
Solve syllogism questions in banking and SSC exams with simple Venn diagrams: rules for all, some and no, the 'possibility' trap, and either-or cases.
By the World MCQ Forum India Editorial Team · 27 October 2026 · 2 min read
Syllogism questions give you two or three statements and ask which conclusions definitely follow. The key word is definitely. You are not asked what could be true, only what must be true in every possible picture.
The fastest reliable method is to draw simple circles.
The four statement types
| Statement | Picture | What you can say for sure |
|---|---|---|
| All A are B | Circle A inside circle B | Some B are A; some A are B |
| Some A are B | Circles A and B overlap | Some B are A |
| No A is B | Circles A and B separate | No B is A; some A are not B |
| Some A are not B | Part of A lies outside B | Nothing about B |
Two rules follow directly:
- “All A are B” never means “All B are A”. All roses are flowers, but not all flowers are roses.
- “Some” works both ways. If some pens are books, then some books are pens.
Step-by-step method
- Draw the first statement with the fewest circles possible.
- Add the second statement without assuming anything extra.
- Test each conclusion: try to draw a picture, still consistent with both statements, in which the conclusion is false. If you can, the conclusion does not follow.
That third step is what separates correct answers from guesses.
Worked examples
Example 1: All cats are dogs. All dogs are birds.
Cats sit inside dogs, and dogs inside birds.
- All cats are birds: follows, because there is no way to draw it otherwise.
- Some birds are cats: follows, because the cat circle is inside the bird circle.
Example 2: Some pens are books. All books are bags.
The overlap of pens and books lies inside bags.
- Some pens are bags: follows (the shared part).
- All bags are pens: does not follow; draw the bags circle much bigger than pens.
Example 3: All roses are flowers. Some flowers are red.
- Some roses are red: does not follow. You can draw the red part of the flower circle away from the roses.
The either-or case
When two conclusions:
- talk about the same two groups,
- are both uncertain, and
- are opposites (one must be true),
the answer is either I or II.
Example: Some chairs are tables. Some tables are doors. Conclusions: I. Some chairs are doors. II. No chair is a door.
Neither is certain, but chairs and doors either overlap or they don’t. One of the two must be true, so the answer is either I or II.
The most common pairs are “some … are” with “no … is”, and “all … are” with “some … are not”.
Three traps to avoid
- Using real-world knowledge. If a statement says “All fish are birds”, accept it. Only the statements count.
- Reversing “all”. “All A are B” says nothing about whether all B are A.
- Two negatives. From “No A is B” and “No B is C”, nothing definite follows about A and C. Look for an either-or pair.
Try our syllogism MCQs, where each explanation describes the picture that proves or disproves the conclusion.