Critical Thinking and Logical Reasoning

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Critical Thinking and Logical Reasoning — Key Facts for Sri Lanka A/L Examination

Core Critical Thinking Skills:

• Analysis: Breaking down complex information
• Evaluation: Judging the value or quality of information
• Inference: Drawing logical conclusions from evidence
• Argument identification: Recognising reasoning patterns
• Assumption identification: spotting unstated premises

Key Logical Fallacies to Avoid:

• Ad hominem: Attacking the person instead of the argument
• False dilemma: Presenting only two options when more exist
• Hasty generalisation: Drawing broad conclusions from few examples
• Begging the question: Using the conclusion as a premise
• Post hoc: Assuming cause from mere sequence

⚡ A/L Exam Tip: In any argument analysis question, identify whether the argument is DEDUCTIVE (conclusive conclusion) or INDUCTIVE (probable conclusion)!

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🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

Critical Thinking and Logical Reasoning — Detailed Study Guide

The Nature of Arguments

What is an Argument?:

• A set of statements (premises) intended to support another statement (conclusion)
• Not fighting or disagreeing — but reasoning from evidence to conclusion

Argument Components:

Component	Description	Example
Premise(s)	Evidence or reasons	”All Sri Lankan citizens who pass A/L can apply to university”
Conclusion	Claim supported by premises	”Therefore, Rangi can apply to university”
Inference	Logical connection between premises and conclusion	—
Hidden assumption	Unstated premise required for argument to work	”Rangi is a Sri Lankan citizen”

Types of Reasoning:

Deductive Reasoning:

• General premise → Specific conclusion
• If premises are true, conclusion MUST be true
• Example:
  • Premise 1: All mammals are warm-blooded
  • Premise 2: Whales are mammals
  • Conclusion: Whales are warm-blooded

Inductive Reasoning:

• Specific observations → General conclusion
• Conclusion is probable, not certain
• Example:
  • Premise 1: The sun rose yesterday
  • Premise 2: The sun rose today
  • Conclusion (probable): The sun will rise tomorrow

Abductive Reasoning:

• Observations → Best explanation
• Used in everyday reasoning and science
• Example: “The road is wet; it probably rained”

Argument Analysis

Steps in Analysing an Argument:

1. Identify the conclusion (what the arguer wants you to believe)
2. Identify the premises (reasons given to support conclusion)
3. Determine the logical connection between them
4. Check for hidden assumptions
5. Evaluate the quality of the reasoning

Question Prompt Indicators:

If question asks…	You need to…
”What is the main conclusion?”	Identify the central claim
”Which statement is an assumption?”	Find unstated premise
”What evidence would strengthen?”	Identify missing support
”What evidence would weaken?”	Find counter-considerations
”What is the flaw in reasoning?”	Identify logical fallacy

Evaluating Premise Quality:

• Strong premises: Factual, verifiable, current, relevant
• Weak premises: Unverified claims, outdated, biased, irrelevant
• Test each premise: “Is this statement true? How do we know?”

Logical Fallacies

Fallacies of Relevance:

Fallacy	Description	Example
Ad hominem	Attacking the person	”We shouldn’t listen to him — he’s been divorced twice”
Appeal to authority	Using authority inappropriately	”A famous actor said this diet works”
Appeal to emotion	Manipulating feelings	”Think of the children who will suffer”
Appeal to tradition	”It’s always been done this way"	"Arranged marriages have worked for centuries”
Bandwagon	”Everyone does this"	"All my friends have the latest phone”
Red herring	Irrelevant distraction	”Why worry about climate change when crime is rising?”
Straw man	Misrepresenting opponent’s position	”They want to eliminate all cars!”

Fallacies of Generalisation:

Fallacy	Description	Example
Hasty generalisation	Few examples → broad conclusion	”My neighbour is unfriendly. All city people are unfriendly”
Sweeping generalisation	Exception ignored	”Fish is good for you. I fed it to my cat and it died”
False dilemma	Only two options presented	”You’re either with us or against us”

Fallacies of Assumption:

Fallacy	Description	Example
Begging the question	Conclusion hidden in premise	”Murder is wrong because it’s illegal”
Circular reasoning	Conclusion proves itself	”The newspaper is trustworthy because it says so”
False cause	Assuming cause from sequence	”The rooster crowed, then the sun rose”

Fallacies of Ambiguity:

Fallacy	Description	Example
Equivocation	Using word with multiple meanings	”Saving money is important. Banks save money. Banks are important”
Amphiboly	Grammatical ambiguity	”I saw the man with the telescope”

⚡ A/L Tip: When you spot a fallacy, name it AND explain WHY it’s a fallacy!

Inference and Conclusion Recognition

Identifying Conclusions: Conclusion indicator words:

• Therefore, thus, hence, so, consequently
• It follows that, this shows that, proves that
• This means, we can conclude, the point is

Premise indicator words:

• Because, since, for, as, given that
• First, second, moreover, furthermore
• The reason is, in fact, evidence shows

Types of Conclusions:

1. Factual conclusions: Based on verifiable evidence
2. Evaluative conclusions: Judgments about value or quality
3. Policy conclusions: Recommendations for action
4. Explanatory conclusions: Reasons for phenomena

Evaluating Conclusions:

• Is the conclusion supported by the evidence?
• Are there alternative conclusions?
• Is the reasoning valid (logically correct)?
• Is the reasoning sound (valid AND premises are true)?

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🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

Critical Thinking and Logical Reasoning — Complete Notes for A/L Sri Lanka

Advanced Logical Structures

Conditional Statements:

Structure	Meaning	Example
If P, then Q	When P is true, Q is true	If you study, you will pass
P only if Q	P implies Q; Q is necessary for P	You pass only if you study
P if Q	Q is sufficient for P	You will pass if you study
If P then Q / If not Q then not P	Contrapositive equivalent	If you don’t study, you won’t pass

Evaluating Conditional Arguments:

• Modus ponens (affirming): If P→Q, P is true, therefore Q is true
• Modus tollens (denying): If P→Q, Q is false, therefore P is false
• Affirming consequent: If P→Q, Q is true, therefore P is true (INVALID!)
• Denying antecedent: If P→Q, P is false, therefore Q is false (INVALID!)

Categorical Syllogisms:

Figure	Form	Example
Barbara (AAA-1)	All B are C; All A are B; ∴ All A are C	All tigers are mammals; All mammals are animals; ∴ All tigers are animals
Celarent (EAE-1)	No B are C; All A are B; ∴ No A are C	No Sri Lankans are European; All Jaffna residents are Sri Lankans; ∴ No Jaffna residents are European
Ferio (EIO-1)	No B are C; Some A are B; ∴ Some A are not C	No Buddhists are Christians; Some people are Buddhists; ∴ Some people are not Christians

Analogical Reasoning:

• Comparing similar cases to draw conclusions
• Structure: A and B share properties 1, 2, 3. A has property 4. Therefore, B probably has property 4.
• Strength depends on relevance and number of shared properties
• Example: “If Sri Lanka and Singapore can develop with good governance, other developing nations possibly can too”

Causal Reasoning:

Type	Description	Example
Necessary cause	Must be present for effect	Oxygen is necessary for fire
Sufficient cause	Guarantees the effect	Drowning is sufficient for death by water
Contributing cause	One of several causes	Many factors contribute to poverty

Causal Fallacies:

• Post hoc ergo propter hoc: “After this, therefore because of this” — assuming causation from sequence
• Correlation confused with causation: Two things happening together doesn’t mean one causes the other
• Complex cause: Oversimplifying multi-causal events

Critical Reading

Steps for Critical Reading:

1. Identify the genre and context: What type of text is this? Who wrote it? When?
2. Identify the main thesis: What is the writer’s central claim?
3. Identify the structure: How is the argument organised?
4. Identify the evidence: What facts, examples, statistics support the argument?
5. Evaluate the evidence: Is it sufficient? Accurate? Relevant? Current?
6. Identify assumptions: What does the writer take for granted?
7. Identify fallacies: Are there any flaws in reasoning?
8. Consider counterarguments: What opposing views exist?
9. Form your own evaluation: Do you agree? Why or why not?

Source Evaluation Checklist:

• Who is the author? What are their qualifications?
• What is the publication? Is it reputable?
• When was it published? Is the information current?
• What is the purpose? To inform, persuade, entertain?
• Is the evidence verifiable?
• Are there any obvious biases?
• Is the reasoning logical?

Bias Types to Watch For:

Bias	Description
Confirmation bias	Seeking only information that confirms existing beliefs
Anchoring bias	Relying too heavily on first information received
Sunk cost fallacy	Continuing because of invested resources
Bandwagon effect	Believing something because many believe it
Authority bias	Accepting authority figures’ opinions uncritically
Availability heuristic	Judging probability by how easily examples come to mind

Problem-Solving with Critical Thinking

Problem-Solving Framework:

1. Define the problem: What exactly is the issue?
2. Gather information: What are the relevant facts?
3. Identify possible causes: What might lead to this problem?
4. Generate solutions: What options exist?
5. Evaluate solutions: What are the pros and cons of each?
6. Select the best solution: Which addresses the problem most effectively?
7. Implement and review: Put it into action, assess results

Decision-Making Framework:

1. State the decision to be made
2. Identify alternatives
3. Establish criteria for evaluation
4. Assess each alternative against criteria
5. Weigh criteria (some may be more important)
6. Make decision
7. Review and adjust

Brainstorming Techniques:

• Free association: Generate ideas without judgment
• SCAMPER: Substitute, Combine, Adapt, Modify, Put to other use, Eliminate, Reverse
• Mind mapping: Visual brainstorming
• SWOT: Strengths, Weaknesses, Opportunities, Threats

Critical Thinking in Sri Lankan Context

Applying Critical Thinking to Sri Lankan Issues:

Education in Sri Lanka:

• Premise: Sri Lanka has high literacy rates
• Premise: But unemployment among graduates remains high
• Premise: Many graduates lack practical skills
• Question: Does education equal economic opportunity?
• Conclusion: Education reform must address skills development

Development Challenges:

• Premise: Sri Lanka achieved middle-income status
• Premise: But inequality persists between regions
• Premise: Urban areas attract resources
• Question: Is development truly inclusive?
• Counterargument: Development takes time; progress is measurable

Environmental Concerns:

• Premise: Sri Lanka has high biodiversity
• Premise: But deforestation and coastal erosion continue
• Premise: Economic development often prioritised over environment
• Question: How to balance development and conservation?
• Critical thinking: Consider alternative development models

Social Issues Analysis Framework:

1. What is the problem?
   - Define precisely

2. Who is affected?
   - Demographics, regions, social groups

3. What are the causes?
   - Immediate and underlying

4. What solutions have been tried?
   - Sri Lankan context, international comparisons

5. What are the alternatives?
   - Policy options, community approaches

6. What are the trade-offs?
   - Benefits vs. costs, winners vs. losers

7. What criteria should guide the decision?
   - Economic, social, environmental, equity

8. What recommendation follows?
   - Based on evidence and reasoning

Critical Thinking in Media and Information

Media Literacy:

• Source attribution: Where does this information come from?
• Fact vs. opinion: Is this verifiable or subjective?
• Hidden agendas: What interest does the author/publisher have?
• Representation: Does this image/text accurately represent reality?
• Framing: How has the information been presented to influence perception?

Evaluating News Sources:

Source Type	Reliability	Verification
Established newspapers	Generally reliable	Cross-check with other sources
Government statements	May reflect official position	Verify independently
Social media	Variable reliability	Check original source
Academic journals	High reliability	Peer review process
Anonymous sources	Caution needed	Corroborate if possible

Fact-Checking Skills:

1. Check the original source (author, publication, date)
2. Cross-reference with reliable sources
3. Check for date — old news may be recycled
4. Look for evidence and citations
5. Consider what perspectives may be missing

⚡ A/L Critical Thinking Question Format: Questions often present an argument and ask you to identify the conclusion, a hidden assumption, a flaw in reasoning, or how to strengthen/weaken the argument. Practice with past papers!

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