What is an Assumption?

An assumption is a hidden idea that the speaker believes to be true without stating it directly.

A simple test:

If the assumption is false, does the statement still make sense?

If No, then it is a valid assumption.

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Example

Statement

“Switch to FreshMint toothpaste for whiter teeth.”

---

Step 1: Identify the claim

The advertisement says:

Use FreshMint
      │
      ▼
Whiter Teeth

---

Step 2: Ask yourself

Why would someone switch?

Only if they believe the toothpaste actually works.

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Step 3: Find the hidden belief

The advertisement never says

“FreshMint can whiten teeth.”

It simply assumes people believe it.

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Diagram

Advertisement

Use FreshMint
      │
      ▼
Whiter Teeth
      ▲
      │
Hidden Assumption

FreshMint can whiten teeth.

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Final Answer

Assumption: FreshMint toothpaste can whiten teeth.

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2. Statement & Course of Action

What is a Course of Action?

A course of action is the best practical solution to solve a problem.

A good course of action should be:

• Practical
• Solve the actual problem
• Be realistic
• Be within someone’s authority

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Example

Statement

Frequent power cuts are affecting businesses.

Course of Action A

Install solar panels for every business.

Course of Action B

Upgrade the local power transformer.

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Step 1: Check Action A

Power Cuts
     │
     ▼
Install Solar Everywhere

Possible?

• Very expensive
• Difficult
• Not practical

❌ Weak action

---

Step 2: Check Action B

Power Cuts
     │
     ▼
Upgrade Transformer
     │
     ▼
Better Power Supply

• Fixes the real problem
• Practical
• Municipality can do it

✅ Strong action

---

Final Answer

Course of Action B is correct.

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3. Statement & Arguments

What is a Strong Argument?

A strong argument is

• Relevant
• Logical
• Based on facts
• Addresses the main issue

A weak argument is

• Emotional
• Personal opinion
• Irrelevant
• Exaggerated

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Example

Statement

Should college education be free?

Argument A

Educated citizens improve the economy.

Argument B

My friend wants free college.

---

Compare

Argument A

Free Education
        │
        ▼
More Educated People
        │
        ▼
Economic Growth

Relevant ✔

---

Argument B

Friend Wants It
       │
       ▼
Free Education

Personal Opinion ✘

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Final Answer

• Argument A → Strong
• Argument B → Weak

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4. Statement & Inference

What is an Inference?

An inference is something that is likely to be true, based on the information given.

It is not guaranteed, only probable.

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Example

Statement

80% of coaching students pass the exam.

Rohan attends coaching.

---

Step 1

100 Students
      │
      ▼

80 Pass

20 Do Not Pass

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Step 2

Since Rohan is one of the coaching students,

he is more likely to pass.

Notice:

It says probably, not definitely.

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Diagram

Coaching Student
        │
        ▼

80% Pass

        │
        ▼

Rohan will
probably pass

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Final Answer

The inference is valid.

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5. Cause & Effect

How to Identify?

Ask two questions:

1. Did one event happen before the other?
2. Can the first event naturally produce the second?

If yes,

Cause
   │
   ▼
Effect

Otherwise, both may simply have the same reason.

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Example

Statements

Company laid off employees.

Company’s share price fell.

---

Possibility 1

Layoffs
    │
    ▼
Investors Panic
    │
    ▼
Stock Falls

Possible.

---

Possibility 2

Poor Business Performance
          │
   ┌──────┴──────┐
   ▼             ▼

Layoffs     Stock Falls

Both are effects of one common cause.

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Final Answer

More information is needed.

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6. Assertion & Reason

How to Solve

Always check in this order.

Assertion True?
      │
      ▼

Reason True?
      │
      ▼

Does Reason Explain Assertion?

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Example

Assertion

Metal feels colder than wood.

Reason

Metal conducts heat faster than wood.

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Step 1

Assertion?

✔ True

---

Step 2

Reason?

✔ True

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Step 3

Does the reason explain the assertion?

Touch Metal
      │
      ▼

Heat Leaves Hand Faster
      │
      ▼

Hand Feels Cold

Yes.

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Final Answer

Both Assertion and Reason are true, and the Reason correctly explains the Assertion.

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7. Statement & Assumption vs Inference

This is one of the most confusing topics.

                Statement

        "FreshMint whitens teeth"

             /             \
            /               \

     Assumption          Inference

Hidden belief        Likely conclusion

"FreshMint works"    "People may buy it"

Remember

• Assumption → What must already be believed?
• Inference → What can probably happen?

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Quick Revision

                    Critical Reasoning

                Statement
                    │
     ┌──────────────┼──────────────┐
     ▼              ▼              ▼

Assumption     Argument      Inference

Hidden Idea    Strong/Weak   Probable Result


     ▼              ▼              ▼

Course of      Cause &       Assertion &
Action         Effect         Reason

Quick Tips

• Assumption → Hidden belief.
• Argument → Check relevance and logic.
• Course of Action → Must be practical and solve the problem.
• Inference → Probably true, not always true.
• Cause & Effect → Check sequence and logical connection.
• Assertion & Reason → Check truth first, then explanation.