Lesson 2.5: Syllogisms & Logical Deductions

Introduction:
Syllogism and logical deduction questions are a key part of SSC reasoning exams. They test your ability to draw conclusions from given statements.

1. Basics

• Statement: A sentence or fact provided.

• Conclusion: A statement that logically follows from the given statement(s).

• Symbols used:

  • All A are B → A ⊆ B

  • No A is B → A ∩ B = Ø

  • Some A are B → A ∩ B ≠ Ø

2. Types of Syllogisms

1. Direct Syllogism: Single statement with one or two conclusions.

2. Multiple Statements: Combine two statements to find logical conclusions.

3. Rules for SSC Exams

• Step 1: Read statements carefully.

• Step 2: Identify the type of statement (All, No, Some).

• Step 3: Use Venn diagrams if necessary.

• Step 4: Determine which conclusion(s) logically follow.

4. Example

Statements:

1. All cats are animals.

2. Some animals are dogs.

Conclusions:
A. Some cats are dogs. → False
B. Some animals are cats. → True

5. Practice Questions

1. Statements: All pens are pencils. Some pencils are erasers. Conclusions?

2. Statements: No A is B. Some C are A. Conclusions?

3. Statements: All fruits are sweet. Some sweet things are candies. Conclusions?

4. Statements: All chairs are furniture. All furniture is wooden. Conclusions?

5. Statements: Some birds can fly. All sparrows are birds. Conclusions?