Evaluate the Argument

Finding the "Swing Vote" Question

A guide to identifying the single most useful piece of information needed to judge an argument's validity.

The Fulcrum
The Test
The Question

What is Your Mission?

You are given an argument that is missing a key piece of information.

Your mission: Find the question whose answer would be *most useful* in determining if the argument is strong or weak.

Analogy: The Litmus Test

Think of the argument as an unknown liquid. The correct answer is the *litmus test* you must perform to find out if the liquid (argument) is valid (acid) or invalid (base).

The Argument

(Unknown Liquid)

The Correct Answer

(The Litmus Test)

"What is the pH level?"

Answer: "pH 3"

(Argument is Valid)

Answer: "pH 8"

(Argument is Invalid)

The Seesaw Analogy

The correct answer is the fulcrum (pivot point). Answering "Yes" or "No" will tip the argument's validity in opposite directions.

The Argument's Conclusion

Answer "YES"
Strengthens
Answer "NO"
Weakens

The Correct Question (The Fulcrum)

If an answer *doesn't* create this "swing," it's wrong. If both "Yes" and "No" make the argument weak (or are both irrelevant), it's not the fulcrum.

Anatomy of an "Evaluate" Question

This question type is a direct test of the argument's unstated assumption.

Argument Flow

Premise (Fact)

"Company X's new ad ran during the Super Bowl."

Unstated Assumption (The Gap)

The author assumes the Super Bowl audience *is* the company's target audience.

Conclusion (Claim)

"Therefore, the ad campaign was a smart investment."

The "Evaluate" Question (The Correct Answer):

"Is the company's target audience heavily represented among Super Bowl viewers?"

Answering this question directly tests the unstated assumption.

Decoding the Question Stems

They all ask: "What information do you *need*?"

  • "The answer to which of the following questions would be most useful in evaluating the argument?"
  • "Which of the following would be most helpful to know in order to assess the conclusion?"
  • "An answer to which of the following would be most relevant to determining the argument's validity?"

The Core Strategy: The Variance Test

This is the *only* strategy you need. It turns an "Evaluate" question into a "Strengthen/Weaken" question.

How to Run the Test

Take an answer choice (which is a question) and give two opposite, extreme answers (e.g., "Yes, 100%" and "No, 0%").

Start: Answer Choice (as a Question)
vs.
Answer A: "YES"
Answer B: "NO"

What is the effect on the conclusion?

STRENGTHENS

What is the effect on the conclusion?

WEAKENS

The "Swing Vote"

If one answer strengthens the argument and the other answer weakens it, you have a "swing"! This is the correct answer.

Variance Test Step 1: Isolate the Argument

Before you test answers, find the core argument.

Argument: "A new mint-flavored toothpaste, 'MintyBrite,' was introduced last year. Since then, sales of our original-flavor toothpaste have dropped by 20%. Therefore, MintyBrite's popularity has clearly *caused* our original-flavor's decline."

Gap/Assumption: The author assumes *nothing else* caused the decline.

Variance Test Step 2: Test an Answer ("Yes")

Let's test this (wrong) answer choice:

Question: "Did MintyBrite's ad campaign also feature the original flavor?"

Test 1: Answer "YES"
"Yes, the campaign featured both."

Impact: This makes the paradox *worse*. Why would sales of the original drop if it was also advertised? This *weakens* the argument's causal claim.

Variance Test Step 3: Test an Answer ("No")

Now, the other extreme:

Question: "Did MintyBrite's ad campaign also feature the original flavor?"

Test 2: Answer "NO"
"No, the campaign *only* featured MintyBrite."

Impact: This *strengthens* the argument. It supports the idea that the new flavor's popularity, driven by its solo ad campaign, is what caused the original's decline.

Variance Test Step 4: Check for a Swing

Let's review the results for our test question:

Answer "NO"
Strengthens
Answer "YES"
Weakens

Verdict: Because the two opposite answers create a *swing* (one strengthens, one weakens), this is a CORRECT answer. It's the right question to ask.

Variance Test: Spotting a WRONG Answer

Let's test this (wrong) answer choice on the same argument:

Question: "Is mint a more popular flavor than original?"

Test 1: Answer "YES"
"Yes, mint is more popular."
Impact: This *strengthens* the claim that MintyBrite's popularity caused the decline.

Test 2: Answer "NO"
"No, original is more popular."
Impact: This is *irrelevant*. It *deepens* the paradox but doesn't help evaluate the ad's impact. It doesn't swing the argument; it just makes us confused.
Verdict: NO SWING. This is a WRONG answer.

Common "Evaluate" Patterns

These arguments show up all the time. The "Evaluate" question will *always* test the assumption in the same way.

Pattern 1: Causal Arguments

Argument: "After we did X, Y happened. Therefore, X caused Y."
Assumption: *Nothing else* caused Y.

Evaluate Question: "Was there any *other factor* (an alternate cause) that could have caused Y?"

X ➔ Y
?
Z ➔ Y

Pattern 2: Survey/Sample Arguments

Argument: "A sample of 100 people showed X. Therefore, the *entire population* believes X."
Assumption: The sample is representative.

Evaluate Question: "Was the sample *biased* in a way that's relevant to X?"

Sample (100)
?
Population (10M)

Pattern 3: Comparison/Analogy

Argument: "Plan X worked for City A. Therefore, Plan X will work for City B."
Assumption: City A and City B are similar in all relevant ways.

Evaluate Question: "Is there a *relevant difference* between City A and City B?"

City A (Apples)
?
City B (Oranges)

Pattern 4: Plan/Proposal

Argument: "We should enact Plan X to achieve Goal Y."
Assumption: The plan won't backfire or have side effects that *prevent* Goal Y.

Evaluate Question: "Does Plan X have a *side effect* or *cost* that would outweigh the benefits or prevent Goal Y?"

The Hall of Shame: Common Traps

1. The "One-Way Street"

This is the #1 trap. "Yes" strengthens, but "No" is irrelevant (or vice-versa). It *must* swing both ways. If it doesn't, it's wrong.

2. The "Irrelevant"

The question is on-topic but doesn't test the *core assumption*. (e.g., Q: "What color was the ad?" A: Irrelevant).

3. The "How?" Trap

The question asks *how* a mechanism works, when we only care *if* it works. (e.g., "By what biochemical process does the drug work?").

4. The "Too Vague" Trap

The question is too general to have an impact. (e.g., "Are there other factors?"). A good answer is *specific* ("Does *weather* affect sales?").

Practice Set 1 (4 Options)

Passage 1: "The town of Smithville has a new automated speed-camera system. The system's proponents claim it will reduce speeding and make the town safer. The town council should approve the system."

The answer to which of the following questions would be most useful in evaluating the argument?

Explanation:
Argument: Cameras ➔ Less Speeding ➔ Safer Town.
Test (B):
"YES": Drivers just speed up again. Impact: Weakens (the system doesn't make the town safer).
"NO": Drivers stay slow. Impact: Strengthens (the system works).
Result: It swings! This is the correct answer.
(A) Cost: "One-Way Street" trap. If it costs too much ("Yes"), it weakens. But if it's free ("No"), it doesn't *strengthen* the claim it makes the town *safer*. It's irrelevant to the *effectiveness*.

Passage 2: "A study of 500 college students found that those who ate breakfast daily had a 15% higher average grade. This shows that eating breakfast is beneficial for academic performance."

An answer to which of the following would be most relevant to determining the argument's validity?

Explanation:
Argument: Causal. Breakfast (X) ➔ Better Grades (Y).
Assumption: There is no alternate cause (Z) that causes both.
Test (C): This question directly tests for an alternate cause (Z = "good habits").
"YES": Good habits (Z) cause both. Impact: Weakens (breakfast isn't the cause).
"NO": No other habits. Impact: Strengthens (breakfast is the likely cause).
Result: It swings! This is a classic Causal Pattern.

Practice Set 2 (5 Options)

Passage 3: "The neighboring town of Jonesburg enacted a 10 PM curfew for teenagers, and their rates of vandalism dropped by 50%. Our town is experiencing a similar wave of vandalism, so we should enact the same 10 PM curfew to solve our problem."

Which of the following would be most helpful to know in order to evaluate the argument?

Explanation:
Argument: Comparison/Plan. Curfew worked in Jonesburg, so it will work here.
Assumption: The situations are relevantly similar.
Test (A):
"YES" (e.g., 90%): Vandalism happened after 10 PM. Impact: Strengthens (the curfew was the clear solution).
"NO" (e.g., 2%): Vandalism happened at 7 PM. Impact: Weakens (the curfew was irrelevant; something *else* solved their problem).
Result: It swings! (D) is a good alternate cause question, but (A) is more specific and tests the *mechanism* of the proposed plan.

Passage 4: "A popular lifestyle magazine, in a survey of its subscribers, found that 80% of respondents exercise at least three times a week. This indicates that most people in this country are health-conscious."

The answer to which of the following questions would be most useful in evaluating the argument's conclusion?

Explanation:
Argument: Survey/Sample. Sample (magazine subscribers) ➔ Population (most people).
Assumption: The sample is representative.
Test (D): This *directly* tests the assumption.
"YES": They are more health-conscious. Impact: Weakens (the sample is biased; we can't conclude anything about "most people").
"NO": They are just as health-conscious. Impact: Strengthens (the sample is representative).
Result: It swings! This is a classic Survey Pattern.

Practice Set 3 (5 Options)

Passage 5: "To reduce costs, a large company plans to cut 10% of its workforce, selecting those to be laid off by a "last-hired, first-fired" policy. The company claims this policy is fair and will not hurt its long-term productivity, as it protects its most experienced workers."

Which of the following would be most important to know in evaluating the company's claim about productivity?

Explanation:
Argument: Plan (fire last-hired) ➔ Goal (won't hurt productivity).
Assumption: "Experienced" (long-tenured) workers are *more* productive than "last-hired" workers.
Test (B): This directly tests that assumption.
"YES": Last-hired are most productive. Impact: Weakens (the plan *will* hurt productivity).
"NO": Last-hired are least productive. Impact: Strengthens (the plan *won't* hurt productivity).
Result: It swings!

Passage 6: "A high-end electronics store saw its sales decline. To boost them, the store moved from its suburban location to a downtown mall. The store's manager claims this move will be successful because the mall attracts a much larger volume of foot traffic."

An answer to which of the following would be most useful in evaluating the manager's claim?

Explanation:
Argument: Plan (move to mall) ➔ Goal (boost sales).
Premise: Mall has more foot traffic.
Assumption: More foot traffic = More *relevant* foot traffic.
Test (A):
"YES": Mall-goers are the target clientele. Impact: Strengthens (the move will likely work).
"NO": Mall-goers are just teenagers at the food court. Impact: Weakens (the move will fail).
Result: It swings! (B) is a "One-Way Street." High rent ("Yes") weakens, but low rent ("No") is irrelevant to *sales*.

Final Interactive Quiz

Test your mastery. Find the "Swing Vote"!

1. (4 options) Argument: "To improve its residents' health, the city of Springfield plans to ban the sale of large sugary sodas. This plan will undoubtedly be successful, as similar bans have proven effective in other cities."

The answer to which of the following questions would be most useful in evaluating the argument's conclusion?

2. (5 options) Argument: "The local fishing industry is collapsing. To save it, the government proposes to give a $1 million subsidy to every fishing boat in the fleet. This will provide the boat owners with the income they need to continue operating."

Which of the following would be most helpful to know in assessing the plan's prospects for success?

3. (5 options) Argument: "A company's profits are falling. The CEO claims this is due to a new, aggressive competitor. As proof, the CEO points out that the competitor's market share has tripled in the last year."

The answer to which of the following would be most useful in evaluating the CEO's explanation?

4. (4 options) Argument: "A new study found that 90% of millionaires own a luxury car. This clearly shows that owning a luxury car is a significant factor in wealth accumulation."

An answer to which question would be most useful in evaluating the argument?

Summary & Next Steps

Key Takeaways

  • Use the Variance Test. Always. It's the only tool you need.
  • Look for the "Swing": The correct answer *must* Strengthen on one side and Weaken on the other.
  • The correct answer is a question that tests the argument's unstated assumption.
  • Watch for the "One-Way Street" trap: it strengthens/weakens on one side but is irrelevant on the other.

Practice Plan

  • Isolate the Assumption: For every CR argument you read, practice identifying the *one* thing the author is *assuming*.
  • Drill the Test: Get fast at the Variance Test. For each answer choice, mentally say "Yes..." (impact?) and "No..." (impact?).
  • Review Your Errors: When you miss one, it's almost *always* because you fell for a "One-Way Street" trap. Analyze *why* one side was irrelevant.

Variance Test: Step 1 (Detailed)

Isolate the Argument. Before looking at the choices, find the *conclusion*. This is your anchor. Everything is judged by how it affects this one statement.

Conclusion: "The town council *should approve* the system."
Premise: "The system's proponents claim it will *reduce speeding* and *make the town safer*."
Assumption: The proponents' claim is true AND relevantly leads to the conclusion.

Variance Test: Step 2 (Detailed)

Test Answer "YES". Take the question from the answer choice and give it a strong "Yes" answer.

Question (B): "Do drivers... start speeding again *after* passing it?"
"YES" Answer: "Yes, drivers hit the brakes for the camera and speed right back up 500 feet later."

Impact on Conclusion: This *weakens* the argument. If drivers only slow down for a moment, the system isn't "making the town safer," it's just creating a "speed trap."

Variance Test: Step 3 (Detailed)

Test Answer "NO". Take the same question and give it a strong "No" answer.

Question (B): "Do drivers... start speeding again *after* passing it?"
"NO" Answer: "No, the presence of cameras makes drivers stay cautious and reduce their speed for their entire trip through town."

Impact on Conclusion: This *strengthens* the argument. It confirms the system works as intended ("reduce speeding" and "make the town safer").

Variance Test: Step 4 (Detailed)

Check for a "Swing". Look at your two impacts side-by-side.

Answer "NO"
➔ STRENGTHENS
Answer "YES"
➔ WEAKENS

Verdict: Because the impacts are opposite, the question is a valid test. It is the "fulcrum" of the argument. This is the correct answer.

Trap Deep Dive: The "One-Way Street"

This is the most dangerous trap. Let's re-examine Trap (A) from the speed-camera question.

Question (A): "How much will the new camera system cost the town?"

Test 1: "YES" (Cost is high): "It will cost $50 million."
Impact: This *weakens* the conclusion ("The council should approve").

Test 2: "NO" (Cost is low): "It is free."
Impact: This is *irrelevant*. It removes an objection, but it does *not* strengthen the claim that the system will *make the town safer*. It just makes it *easier to approve*. It doesn't test the argument's *effectiveness*.
Verdict: NO SWING. Only one side had a relevant impact. This is a trap.

Trap Deep Dive: The "Irrelevant" (C)

Let's test Trap (C) from the speed-camera question.

Question (C): "What is the margin of error for the... radar?"

Test 1: "YES" (Error is high): "The radar is wrong 30% of the time."
Impact: This might be *unfair*, but it doesn't mean the system won't *reduce speeding*. Drivers will still slow down to avoid the (unfair) ticket. Irrelevant to the goal of "making the town safer."

Test 2: "NO" (Error is low): "The radar is 100% accurate."
Impact: This makes the system *fairer*, but doesn't tell us if it *makes the town safer*. It's irrelevant to the conclusion.
Verdict: NO SWING. Both answers are irrelevant to the core claim.

Quiz 2: Deep Dive (Plan vs. Cause)

Let's analyze Quiz Q2: "The fishing industry is collapsing. To save it, the government proposes a subsidy... This will provide the income they need to continue operating."

Plan: Give money. Goal: "Continue operating."
Assumption: The *reason* they are failing is a *lack of money* (high operating costs).
Evaluate Question (B): "Is the collapse caused by a *shortage of fish*, or by *high operating costs*?"Test 1 (Shortage of Fish): Impact: WEAKENS. Giving them money is useless if there are no fish to catch. The plan will fail.
Test 2 (High Costs): Impact: STRENGTHENS. The plan directly solves the problem.
Result: A perfect swing.

Quiz 3: Deep Dive (Causal)

Let's analyze Quiz Q3: "Profits are falling. CEO claims this is *due to a new, aggressive competitor*. As proof, the CEO points out the competitor's market share has tripled..."

Argument: Competitor (X) ➔ Falling Profits (Y).
Assumption: There is no *other cause* (Z) for falling profits.
Evaluate Question (E): "Whether the *overall* market... has shrunk significantly." (This proposes an alternate cause, Z).
Test 1 (YES, market shrunk): Impact: WEAKENS. The shrinking market (Z) is the real cause, not the competitor (X).
Test 2 (NO, market is fine): Impact: STRENGTHENS. This rules out Z, making it more likely X is the cause.
Result: A perfect swing.

Quiz 4: Deep Dive (Causal Direction)

Let's analyze Quiz Q4: "90% of millionaires own a luxury car. This clearly shows that owning a luxury car is a significant factor in wealth accumulation."

Argument: Luxury Car (X) ➔ Wealth (Y).
Assumption: The causal direction isn't reversed (i.e., Wealth (Y) ➔ Luxury Car (X)).
Evaluate Question (C): "What percentage... owned a luxury car *before* they became wealthy?" (This tests the *timing* and *direction* of causality).
Test 1 (High %, e.g., 80%): Impact: STRENGTHENS. This shows X came *before* Y.
Test 2 (Low %, e.g., 2%): Impact: WEAKENS. This shows Y came *before* X (they got rich, *then* bought the car).
Result: A perfect swing.

Final Takeaway

The "Evaluate" question is the ultimate test of your understanding of an argument's core assumption. Every other CR question type is built on this foundation. Master the Variance Test, and you will master all of Critical Reasoning.