Causal reasoning on the LSAT: correlation, causation, and what breaks the link

Causal arguments are among the most common on the exam, and they nearly all share one shape: two things were observed together, and the author concludes one produced the other. Recognizing that shape is most of the work, because once you see it the attacks are standard.

Spot the causal claim

Look for verbs doing causal work — caused, produced, led to, resulted in, is responsible for, explains — and for the softer versions that are still causal: contributed to, drove, is behind. A conclusion recommending an action is usually causal too, since it assumes doing the thing produces the outcome.

The evidence underneath is almost always weaker than the claim: a correlation, a before-and-after comparison, or one group differing from another. That gap between what was observed and what is concluded is where every question on the type operates.

The four standard attacks

• Alternative cause. Something else produced the effect. A town credits its new streetlights for fewer night collisions; traffic volume halved over the same period.
• Reverse causation. The arrow points the other way. Productive teams are said to be productive because they meet often — or teams that are already productive have more to meet about.
• Common cause. A third factor produced both, so they move together and neither causes the other.
• Coincidence. With enough measurements, some things move together for no reason. Weakest of the four, and occasionally the credited answer.

On a Weaken question, the credited answer is usually one of those four. On a Strengthen question it is usually one of them being RULED OUT — which is why strengtheners so often read like they are about something irrelevant until you notice they are closing an alternative explanation.

What a strengthener actually looks like

Not more of the same correlation. Restating that the two things occurred together adds nothing, because that was already the evidence. What helps is eliminating a competing story, or showing the effect appears when the cause is introduced and disappears when it is removed.

This is also why Evaluate questions cluster on causal arguments. The useful question to ask is almost always one that probes an alternative explanation, because that is the assumption the argument is resting on.