Critical Reasoning

🟢 Lite — Quick Review (1h–1d)

Rapid summary of critical reasoning skills for the LAT analytical section.

Critical reasoning evaluates the strength of arguments — identifying assumptions, flaws, evidence, and conclusions.

Parts of an Argument:

1. Premise(s) — The evidence or reasons offered to support the conclusion
2. Conclusion — The main claim being argued for
3. Assumption(s) — Unstated premises that must be true for the argument to work

How to Identify Conclusions:

Look for indicator words:

• Conclusion indicators: therefore, thus, hence, consequently, so, this shows that, we can conclude, it follows that, this proves
• Premise indicators: because, since, for, as, given that, owing to, due to, the reason is

If no indicator word is present, ask: “What is the author trying to convince me of?” That is likely the conclusion.

Question Types in Critical Reasoning:

1. Strengthen — Which option makes the argument stronger?
2. Weaken — Which option undermines the argument most?
3. Assumption — What must be true for the argument to hold?
4. Conclusion — What is the main conclusion?
5. Flaw — What is the reasoning error in the argument?
6. Parallel — Which argument has the same logical structure?

⚡ LAT Exam Tip: For assumption questions, find the gap between premises and conclusion. The assumption fills that gap — it is something unstated that must be true for the reasoning to work.

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🟡 Standard — Regular Study (2d–2mo)

For LAT students who want to systematically approach critical reasoning questions.

Evaluating Evidence:

Good arguments rely on solid evidence. Assess evidence by checking:

1. Relevance — Does the evidence actually support the conclusion?
2. Credibility — Is the source reliable and expert?
3. Sufficiency — Is there enough evidence to warrant the conclusion?
4. Consistency — Does the evidence align with other known facts?

Common Argumentative Weaknesses:

Flaw	Description	Example
Circular reasoning	Conclusion assumed in premise	”The law is just because it says so”
False cause	Assuming one event caused another because it preceded	”It rained after the ceremony, so the ceremony caused rain”
Hasty generalisation	Drawing broad conclusions from insufficient examples	”My neighbour is rude; therefore all neighbours are rude”
Ad hominem	Attacking the person rather than the argument	”Don’t listen to him — he’s a criminal”
Appeal to authority	Claiming something is true just because an authority said it	”A famous athlete says this supplement works, so it must”
False dilemma	Presenting only two options when more exist	”You’re either with us or against us”
Slippery slope	Assuming one event will inevitably lead to extreme consequences	”If we allow A, then Z will eventually happen”
Red herring	Introducing an irrelevant topic to distract	”Why worry about the budget when the real issue is crime?”
Appeal to emotion	Using fear, sympathy, or anger rather than logic	”Think of the children — vote yes”

Assumptions:

An assumption is an unstated premise that must be true for the argument to work. There are two types:

1. Explicit (concealed) assumptions — Things the author assumes the audience knows or accepts
2. Implicit (hidden) assumptions — Things that must be true for the premises to support the conclusion

Finding Assumptions:

Ask: “What must be true for the conclusion to follow from the premises?” OR: “What information is missing that would make this argument complete?”

Strengthening Arguments:

To strengthen an argument, you can:

1. Provide additional evidence that directly supports the conclusion
2. Eliminate an alternative explanation for the evidence
3. Show that a premise is true
4. Bridge a logical gap between premises and conclusion

Weakening Arguments:

To weaken an argument, you can:

1. Show a premise is false or questionable
2. Introduce evidence that supports an alternative conclusion
3. Demonstrate that the evidence does not actually support the conclusion
4. Point out a logical flaw in the reasoning

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🔴 Extended — Deep Study (3mo+)

Comprehensive critical reasoning techniques for LAT students aiming for high scores.

The Structure of Arguments:

Arguments can be simple or complex:

Simple Arguments: One premise → One conclusion Tandem Arguments: Multiple premises → One conclusion (convergent) Chain Arguments: Premise → Intermediate conclusion → Final conclusion (serial)

Convergent Evidence: Two independent premises both support the same conclusion Serial Chain: A conclusion from one becomes a premise for the next

Evaluating Chain Arguments:

In a chain argument, if any link is broken, the entire chain collapses. Check each step carefully:

• Premise 1 supports intermediate conclusion
• Intermediate conclusion (plus possibly more premises) supports final conclusion

Types of Evidence:

Type	Description	Strength
Expert opinion	Testimony from qualified specialist	Moderate — depends on expertise and lack of bias
Statistical evidence	Data from surveys, studies	Moderate to strong — depends on sample size and methodology
Anecdotal evidence	Personal examples or stories	Weak — not representative
Analogical evidence	Comparison based on similarities	Moderate — depends on relevance of similarities
Precedent	Past cases applied to present	Moderate to strong — depends on how analogous cases are
Casual observation	What one has personally seen	Weak — limited perspective

Statistical Reasoning:

Many arguments rely on statistics. Watch for:

1. Small sample sizes — Generalising from too few cases
2. Misleading averages — Mean vs median vs mode
3. Correlation vs causation — Two things changing together doesn’t mean one caused the other
4. Cherry picking — Selecting data that supports while ignoring data that contradicts
5. Percentage errors — Base rate problems (if something increases by 100% from a very small base, it may still be insignificant)

The Most Common Fallacies in LAT Questions:

1. Circular Reasoning (Begging the Question): The premise simply restates the conclusion in different words. Argument: “The defendant is guilty because he committed the crime he is charged with.”

2. False Dichotomy (False Dilemma): Presenting only two options when several exist. Argument: “You’re either a patriot or a traitor.”

3. Appeal to Popularity (Argumentum ad Populum): Assuming something is true because many people believe it. Argument: “Most people believe capital punishment is wrong, so it is wrong.”

4. Appeal to Tradition: Assuming something is correct because it has always been done that way. Argument: “This has been the practice for 50 years, so it must be correct.”

5. Complex Question: Asking a question that presupposes the answer. Argument: “Have you stopped cheating on your exams?” (presupposes you were cheating)

6. Composition: Assuming what is true of parts is true of the whole. Argument: “Every part of this machine is lightweight, so the machine is lightweight.”

7. Division: Assuming what is true of the whole is true of each part. Argument: “This university is excellent, so every professor here is excellent.”

The Principle of Charity:

When analysing arguments, always interpret them in the strongest possible form before criticising. Steel-man your opponent’s position: make their argument as strong as it can be, then evaluate whether it succeeds.

⚡ LAT Critical Reasoning Strategy:

1. Read the passage once — Identify the main conclusion
2. Re-read carefully — Identify the premises offered to support it
3. Note any unstated assumptions — These are often the answer to assumption questions
4. Consider alternative explanations — These are useful for weaken questions
5. Check for common fallacies — Which fallacy does this reasoning commit?
6. Evaluate the evidence quality — Is the evidence sufficient and credible?
7. Select the answer — Which option best fits your analysis?

Answering Specific Question Types:

Strengthen: Choose the option that eliminates an alternative explanation, provides additional supporting evidence, or shows a premise is true.

Weaken: Choose the option that reveals a false assumption, questions the credibility of evidence, or shows the evidence is consistent with an alternative conclusion.

Assumption: Choose the option that must be true for the premises to support the conclusion — it is a necessary condition, not merely a helpful addition.

Flaw: Choose the option that accurately describes the reasoning error made in the argument.