Syllogism - The Complete Basics
Understand SSC-CGL Syllogism using the Venn-diagram method, the four statement types, combination rules, the Either-Or trick, a fully worked example, and a practice quiz.
By the PadhoDost Team · 📖 7 min read · Updated 4 August 2026
Part of SSC CGL & Banking prep🧠 Circles inside circles
Imagine three buckets: one for all 'roses', a bigger one for all 'flowers', and a huge one for all 'red things'. If you drop every rose into the flower bucket, and every flower into the red bucket, then without checking each rose you already know every rose is red. Syllogism is just this bucket game drawn as overlapping circles - you decide what MUST be true only from where the circles sit.
What Syllogism Tests
You are given two or more statements (premises) and some conclusions. You must decide which conclusions definitely follow from the statements - not what is true in real life, only what the statements force to be true. Even if a conclusion sounds obviously true from general knowledge, it counts only if the statements guarantee it. The cleanest tool is the Venn diagram.
The Four Statement Types
| Statement form | What it means | Valid conversion (also true) |
|---|---|---|
| All A are B | Every A sits inside B | Some B are A |
| No A is B | A and B are completely separate | No B is A |
| Some A are B | At least one A is also B | Some B are A |
| Some A are not B | At least one A lies outside B | (no valid conversion) |
The Venn-diagram method
- 1Draw a circle for each term exactly as the statements demand.
- 2'All A are B' -> circle A drawn fully inside circle B.
- 3'No A is B' -> two separate, non-touching circles.
- 4'Some A are B' -> two circles overlapping, and mark the shared middle part.
- 5Test each conclusion: it follows ONLY if it stays true in every possible way you could draw the diagram.
| Premise 1 + Premise 2 (shared middle term) | Valid conclusion |
|---|---|
| All + All | All |
| All + No | No |
| Some + All | Some |
| Some + No | Some are not |
| Some + Some | No definite conclusion |
| No + No | No definite conclusion |
📝 Worked Example
Statements: All pens are books. All books are red.
Draw it: the pens circle sits inside the books circle, which sits inside the red circle - so pens end up inside red too.
Conclusion I - 'All pens are red': in the diagram every pen is inside red, so it MUST be true. Follows.
Conclusion II - 'Some red are pens': since all pens are red, those items are both red and pens, so at least some red things are pens. Follows.
Result: both conclusions follow.
Remember these
- ✓Know the picture of all four forms: All, No, Some, Some-not.
- ✓Solve with Venn diagrams; a conclusion must survive in every possible drawing.
- ✓'Some A are B' also gives 'Some B are A'; 'No A is B' also gives 'No B is A'.
- ✓'All A are B' does NOT give 'All B are A' - only 'Some B are A'.
- ✓Watch for complementary pairs to grab easy 'Either-Or' marks.
⚡ Quick check
Statements: All roses are flowers. Some flowers are red. Conclusions: I. Some roses are red. II. All flowers are roses. Which follows?
Ready to test yourself? 🎯
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