Syllogism: Reasoning Ability Notes for Assam Forest Guard

Syllogism – Easy Study Notes

(For the Assam Forest Guard Reasoning Ability test)

1. What is a Syllogism?

A syllogism is a short logical argument.
It has two premises (statements we accept) and one conclusion (what we must show follows).
It is like a mini‑story that forces you to connect the dots.

Everyday analogy

Think of a chain of dominoes.
Premise 1 is the first domino,
Premise 2 is the second domino,
the conclusion is the last domino that falls.
If the first two fall, the last must fall too—unless the chain is broken.

2. Parts of a Syllogism

Part	What it looks like	Example
Major Premise	General rule	“All trees are plants.”
Minor Premise	Specific case	“The oak is a tree.”
Conclusion	What follows	“The oak is a plant.”

Tip: The middle word (e.g., “tree”) connects the two premises.

3. How to Solve a Syllogism

Identify the three terms
- A = subject of major premise
- B = middle term (connects A & C)
- C = subject of conclusion
Check the logical flow
- Does the major premise say something about A and B?
- Does the minor premise say something about B and C?
- If yes, the conclusion about A and C usually follows.
Look for the pattern
- The most common pattern is:
  All A are B.
  All B are C.
  ∴ All A are C.
Beware of false patterns
- If the connection is broken (e.g., the middle term isn’t shared), the conclusion is invalid.

4. Tiny Example

Statement	Text
Major Premise	“All birds can fly.”
Minor Premise	“Penguins are birds.”
Conclusion	“Penguins can fly.”

Why it’s wrong

The middle term “bird” is shared, but the first premise is not true for all birds (penguins can’t fly).
So the conclusion does not follow.

5. Quick Pattern Cheat Sheet

Pattern	Example	Valid?
A → B , B → C ⇒ A → C	All mammals are animals. All animals are living. ⇒ All mammals are living.	✔️
All A are B, All B are C, ∴ All A are C	All flowers are plants. All plants are green. ⇒ All flowers are green.	✔️
All A are B, All C are B, ∴ All A are C	All cats are animals. All dogs are animals. ⇒ All cats are dogs.	❌ (no link between A and C)
All A are B, No B are C, ∴ No A are C	All cars are vehicles. No vehicles are boats. ⇒ No cars are boats.	✔️

6. Practice Problems

Instructions: Read each set of two statements. Write the correct conclusion or say “No valid conclusion.”

#	Premises	Conclusion (your answer)
1	All trees are plants. All plants are green.
2	All books are paper. No paper is metal.
3	All fish are animals. All animals are wet.
4	All cars are vehicles. All trucks are vehicles.
5	No birds are mammals. All mammals are warm‑blooded.

7. Answer Key

#	Correct Conclusion
1	All trees are green.
2	No books are metal.
3	All fish are wet.
4	❌ (No valid conclusion – cars and trucks are separate groups.)
5	❌ (No valid conclusion – no link between birds and mammals.)

8. Tips for the Test

Read slowly. The middle term is key.
Write down the three terms (A, B, C) on a small piece of paper.
Check if the conclusion uses the same A and C that appear in the premises.
Avoid “double negatives.”
Practice a few more to get comfortable spotting the pattern quickly.

Final Thought

A syllogism is just a short story that forces you to connect two facts. Think of it as linking two dominoes—if they’re correctly connected, the last one will fall. Happy practicing!