Cause-effect reasoning appears across Weaken, Strengthen, and Assumption question types. Many GMAT arguments make causal claims that can be attacked or defended in predictable, systematic ways.

A) The Basic Causal Structure

An argument with causal reasoning states (or implies): A causes B. The evidence cited is typically a correlation (A and B tend to occur together). But correlation ≠ causation, and the GMAT exploits this gap extensively.

B) Four Ways to Attack a Causal Claim

• Alternative cause: some other factor C (not A) is the real cause of B. The correlation between A and B exists, but A is not driving it.
• Reversed causation: B actually causes A, not the other way around. The causal arrow is backwards.
• Mere coincidence: A and B happen together by chance — no causal relationship at all.
• Confounding variable: a third factor C causes both A and B, creating a spurious correlation between A and B without any direct causal link.

C) Four Ways to Strengthen a Causal Claim

• Eliminate alternative causes: show that no other factor could explain B. Directly defends the causal claim.
• Confirm the causal direction: show that A preceded B in time, or that when A is removed, B disappears.
• Dose-response relationship: more A → more B. A gradient relationship strongly supports causation.
• Mechanism: explain how A causes B through an intermediate step (provides the missing causal link).

D) Assumption in Causal Arguments

When an argument moves from correlation to causation, the core assumption is: "No alternative cause explains the correlation." Correct assumption answers are often phrased: "A factor other than [A] did not cause [B]."

E) Causal Language to Recognize

causes, leads to, results in, produces, is responsible for, contributes to, brings about, triggers, is due to, because of, owing to, explains why.

F) Classic GMAT Causal Pattern

Structure: "Researchers observed that people who do X have higher rates of Y. Therefore X causes Y."

Correct weakener: "People who do X also tend to do Z, and Z is a known cause of Y." — introduces alternative cause (confound).

Correct strengthener: "When X was removed from a control group's routine, rates of Y dropped significantly." — confirms causal direction.

G) Strategy: What to Pre-Think

After identifying a causal claim:

1. Name the cause (A) and the effect (B) precisely.
2. For weaken: pre-think "What alternative causes could explain B without A?"
3. For strengthen: pre-think "What would rule out alternative causes or confirm the direction?"
4. For assumption: pre-think "What must be true to rule out reversed causation or alternative causes?"