Syllogism (Basic rules, Venn diagrams) for IBPS PO Exam 2025

Syllogism is a key topic in the Reasoning Ability section of the IBPS PO Exam 2025, both in Prelims and Mains. It tests a candidate’s logical reasoning skills and the ability to draw valid conclusions from given statements. Although the concept is simple, the options can be confusing if you’re not well-versed in its basic rules. With the rise of new pattern questions, understanding traditional syllogism using Venn diagrams is even more crucial, as it lays the foundation for solving both old and new types quickly and accurately.

Syllogism for IBPS PO 2025

A syllogism is a form of logical reasoning where conclusions are drawn from two or more statements (also called premises). These statements use universal and particular quantifiers such as all, some, or no. Your job is to evaluate whether the conclusions logically follow the given statements.

Types of Statements in Syllogisms

Basic Rules of Syllogism

To solve syllogism questions correctly, follow these 5 fundamental rules:

Rule 1: All → Some

If “All A are B,” then “Some A are B” is automatically true.

Example:

Given: All dogs are animals.

Conclusion: Some dogs are animals. (Valid)

Rule 2: No → No & Some Not

If “No A is B,” then:

“No B is A” (Reverse is true).

“Some A are not B” is always true.

Rule 3: Some → Some (Reversible)

If “Some A are B,” then “Some B are A” is also true.

Example:

Given: Some birds are parrots.

Conclusion: Some parrots are birds. (Valid)

Rule 4: Some + No = No Conclusion

If one statement is “Some” and the other is “No,” no definite conclusion can be drawn.

Rule 5: Two Particular Statements → No Conclusion

If both given statements are “Some” or “Some…not,” no valid conclusion follows.

Understanding “Only”, “Few” and “Only a Few” Statements of Syllogism

Only A are B

This means All B are A, but it doesn’t imply All A are B.

Example: “Only cats are pets” = All pets are cats.

Only a Few A are B

This implies: This is a hybrid case that explicitly denies a complete overlap.

Some A are B, and

Some A are not B.

Few A are B

In syllogism, “Few” is generally treated like “Some”- meaning at least one but not all. But it can subtly indicate that some A are B, with a suggestion (not certainty) that some are not.

Examples:

Example 1: Statements:

Few laptops are durable.

All durable items are expensive.

Conclusions:

Some laptops are expensive.

Most laptops are not expensive.

Answer:

Conclusion 1 (Valid – Few → Some overlap).

Conclusion 2 (Invalid – “Most” cannot be confirmed).

Example 2: Statements:

Most Indians are cricket fans.

Some cricket fans love football.

Conclusions:

Some Indians love football.

No cricket fan is Indian.

Answer:

Conclusion 1 (Possible but not definite).

Conclusion 2 (Invalid– contradicts given statements).

Using Venn Diagrams to Solve Syllogisms

Venn diagrams are the most reliable method to solve syllogism questions. They visually represent the relationship between sets (or groups) mentioned in the statements. Here’s how to draw Venns for each type:

All A are B → Circle A completely inside B.

No A is B → Two circles A and B that do not touch.

Some A are B → Overlapping part between A and B.

Some A are not B → Part of A lies outside B.

Steps to use Venn diagrams:

• Read and understand all the statements clearly.
• Draw a diagram based on the structure of the statements.
• Examine each conclusion against the diagram.
• Mark the conclusions that definitely follow.
• Use simple circles; don’t overcomplicate.
• Use overlaps carefully—only when “some” is involved.
• Don’t assume intersections unless explicitly stated.
• For “no” statements, never let the circles touch.

Common Mistakes to Avoid

• Assuming “Some A are B” implies “Some B are A” (not always valid).
• Thinking “Few” means “very few” — treat it as “some” in logic.
• Misinterpreting “Only” statements as “All”.
• Jumping to conclusions without drawing a Venn diagram.
• Overlooking conclusions that are possibly true but not definitely true.

Practice Approach for Syllogism

• Start with two-statement basic problems.
• Gradually move to three-statement and new-pattern questions.
• Focus on possibility-based, “either-or”, and “only a few” cases.
• Regularly solve questions from previous year papers and mock tests.
• Analyze incorrect answers to understand reasoning gaps.