Syllogism Topics

Syllogism is an important topic in the Reasoning Ability section of most placement tests and competitive exams. It is a form of logical reasoning based on two or more statements (premises) followed by one or more conclusions.

Candidates must determine whether the given conclusions logically follow from the statements.

Key Topics in Syllogism

1. Categorical Syllogism

This topic deals with logical reasoning based on categorical statements such as:

• All A are B

• Some A are B

• No A are B

• Some A are not B

Candidates must analyse the relationship between different categories and determine valid conclusions.

2. Venn Diagrams

Venn diagrams are the most common method used to solve syllogism questions.

Candidates may be asked to:

• Draw Venn diagrams based on the given statements

• Identify relationships between different groups

• Check whether conclusions follow logically

3. Rules of Syllogism

Understanding the basic statement types is essential:

• A (Universal Affirmative): All A are B

• E (Universal Negative): No A are B

• I (Particular Affirmative): Some A are B

• O (Particular Negative): Some A are not B

These rules help in determining the validity of conclusions.

4. Possibility Cases

In some questions, conclusions are based on possibility rather than certainty.

Candidates must:

• Consider different logical scenarios

• Identify conclusions that may be possible but not definite

5. Validity of Conclusions

The main objective in syllogism is to:

• Check whether conclusions logically follow

• Identify definite and possible conclusions

• Avoid assumptions not supported by the premises

Why Syllogism is Important

This topic tests a candidate’s:

• Logical reasoning skills

• Analytical thinking

• Decision-making ability

• Understanding of relationships between groups

Strong command over syllogism helps improve accuracy and speed in reasoning sections.

Practice Examples

Example 1

Premise 1: All cats are mammals.
Premise 2: Some mammals are carnivores.

Conclusion:
A) All cats are carnivores
B) Some cats are carnivores
C) All carnivores are cats
D) Some mammals are cats

Example 2

Premise 1: No birds can swim.
Premise 2: All ducks are birds.

Conclusion:
A) All birds can swim
B) No duck can swim
C) All ducks can swim
D) Some birds can swim

Example 3

Premise 1: All roses are flowers.
Premise 2: Some flowers are red.

Conclusion:
A) All red things are flowers
B) Some roses are red
C) All red things are roses
D) Some flowers are roses

Example 4

Premise 1: No doctors are engineers.
Premise 2: All engineers are professionals.

Conclusion:
A) No professionals are doctors
B) All doctors are professionals
C) Some engineers are doctors
D) Some professionals are engineers

Example 5

Premise 1: Some athletes are swimmers.
Premise 2: All swimmers are fit.

Conclusion:
A) All athletes are fit
B) Some athletes are not fit
C) All fit people are athletes
D) Some fit people are swimmers