Critical Reasoning

Every Critical Reasoning argument has three parts. Your first job on every question — before you even read the question stem — is to identify them:

Mental model. Every CR argument has three parts: evidence, conclusion, and the unstated gap that bridges them. The question is always about the gap — strengthening it, weakening it, naming it, evaluating it. Find the gap before you read the answer choices, and the right answer announces itself; read the choices first and you're solving by feel.

1. Conclusion. What the author wants you to believe. The main claim. Usually introduced with signal words: "therefore," "thus," "hence," "it follows that," "the chain's management concludes," "researchers hypothesize," "critics argue."

2. Evidence (or premises). The facts and reasons the author offers in support of the conclusion. Usually descriptive statements: data, studies, observations, historical facts. No "therefore" attached.

3. The gap. The unstated leap from evidence to conclusion. This is the single most important thing to identify on every CR question — because nearly every CR question (strengthen, weaken, assumption, flaw) is about this gap. The gap is whatever else would have to be true for the evidence to actually prove the conclusion.

Worked example. "A regional grocery chain launched a loyalty program three months ago. Since then, revenue is up 8%. The chain's management concludes the loyalty program is responsible."

• Conclusion: The loyalty program caused the revenue increase.
• Evidence: Program launched 3 months ago; revenue up 8% in that period.
• Gap: "No other explanation accounts for the revenue increase." The argument assumes that nothing else changed in those 3 months (no ad campaign, no competitor closing, no seasonal effect, no new products).

Notice how the gap is phrased as what the argument takes for granted. That's the template: look at the evidence, look at the conclusion, and ask "what else would have to be true to get from here to there?"

The three moves in order:

1. Find the conclusion. Underline or mentally tag the main claim. Signal words help, but sometimes the conclusion is at the beginning, sometimes the end, sometimes the middle.
2. Find the evidence. Everything else in the passage that's presented as fact.
3. Find the gap. What assumption bridges the two? What alternative explanation could exist?

Once you've done these three moves, then read the question stem. Not before. The structure is the same regardless of which of the nine question types you're asked — the gap is always what you're working with.

Conclusion vs. evidence — the "why" test. If you can insert "because" or "the reason is" between two statements, the second is evidence for the first. "The loyalty program caused the revenue rise (conclusion) because revenue went up 8% after launch (evidence)." Always read evidence as answering the question "why does the author believe the conclusion?"

Common conclusion signal phrases:

Note the last one: if the author describes what management believes, the author's own conclusion may be that management is wrong. Reading for who is making the claim matters.

Common evidence signal phrases: "Since…", "Because…", "Given that…", "After all…", "In fact…", "Studies show…", "Data indicate…"

Recall check. Close your eyes. State the three parts of every CR argument. Now recall: which part is almost always the subject of the question you'll be asked? (Answer: the gap — the assumption bridging evidence to conclusion.) Forced retrieval of the skeleton makes it available on the next 74 CR questions in this chapter; re-reading the paragraph doesn't.

Trap to watch. Don't confuse premises stated by the author with claims the author actually endorses. The author might describe critics' views only to refute them. Track whose argument you're evaluating — the narrator's, the critic's, or the researcher's. The conclusion you must evaluate is the one the question stem points you at.

Strengthen and weaken questions are mirror images. The same argument can be strengthened or weakened by opposite pieces of information, both of which bear on the same gap. Learn them together.

The template.

• Strengthen: find the answer choice that, if true, makes the argument's gap smaller — i.e., makes it more likely that the evidence supports the conclusion.
• Weaken: find the answer choice that makes the gap larger — i.e., suggests an alternative explanation or undermines a critical link.

The most powerful weakener: the alternative cause. If the argument claims X caused Y, a weakener points out that something other than X also changed, and could have caused Y.

"Loyalty program → revenue up" argument. A weakener: "The chain also launched a major advertising campaign during the same period." Now there's a second plausible cause. The argument doesn't prove loyalty was the driver.

The most powerful strengthener: the control case. If the argument claims X caused Y, a strengthener shows that without X, Y didn't happen elsewhere.

Same argument. A strengthener: "A competing chain in the same region without a loyalty program saw revenue decline by 2%." Now we've effectively run an experiment — same market, no program, different outcome. Makes it much more likely that the program caused the lift.

The question stem decoder:

The five types of weakeners. Memorizing these five patterns means you'll recognize the correct answer on sight.

1. Alternative cause. Something else could have caused the effect.
2. Reverse causation. The effect actually caused the "cause." (Example: sick kids move to green-space neighborhoods → doesn't mean green space prevents asthma.)
3. Confounding variable. A third factor correlates with both the "cause" and the effect. (Example: green-space neighborhoods are also higher-income.)
4. Flawed data. The evidence isn't representative (sample too small, biased selection, etc.).
5. Broken link. The mechanism doesn't actually work the way the argument assumes.

The five types of strengtheners. Exact mirrors:

1. Rule out alternative causes. Show nothing else changed.
2. Rule out reverse causation. Show the cause preceded the effect and not vice versa.
3. Rule out confounders. Show the correlation holds even when the third factor is controlled for.
4. Confirm the data is representative. Larger sample, unbiased selection, etc.
5. Establish the mechanism. Show how the cause produces the effect (e.g., "vegetation absorbs airborne particulates, a known asthma trigger").

Example (strengthen via mechanism). Argument: "More green space leads to lower asthma." The answer "vegetation absorbs airborne particulate matter, a known asthma trigger" is the mechanism. It turns a correlation into a plausible causal story.

Example (weaken via confounding variable). Same argument. The answer "green-space neighborhoods also have higher median incomes" introduces income as a third variable that could independently explain both the green space and the lower asthma rates. Weakens.

Elimination technique: the "irrelevant" trap. Most wrong answers on strengthen/weaken are irrelevant — they talk about something that's true but doesn't touch the gap. Read each answer and ask: "does this tell me something about how the evidence connects to the conclusion?" If no, eliminate.

The "opposite direction" trap. When tired under time pressure, students on strengthen questions pick a weakener and vice versa. Before finalizing, re-check the question stem: am I supposed to support or undermine this argument? A 2-second sanity check prevents a 30-second error.

Self-explanation prompt. Why are strengthen and weaken mirror images? If you can say "because both operate on the same gap between evidence and conclusion — strengtheners narrow it, weakeners widen it," you've internalized the unified structure and will solve both types with the same three-step process.

Trap to watch. "Partial strengtheners" and "partial weakeners." Sometimes an answer weakens one premise but strengthens a different one, or addresses only a minor aspect of the argument. The right answer addresses the central gap. Read all five before committing.