The causation flaw
Correlation is not causation, and the LSAT tests this constantly.
Fallacy vs. flaw, on this site. Our fallacy page on correlation vs. causation teaches the general error. This page is about the LSAT version: in Flaw questions, the right answer is usually worded as "confuses correlation with causation" or "fails to consider alternative explanations." Learn to spot the shape, then match the wording.
Start with the general version: the fallacy page. Then come back here for the test-day version.
What it is
The causation flaw happens when an argument sees two things happen together and concludes that one caused the other. The evidence shows a correlation. The conclusion claims a cause. That jump is the flaw.
It also covers the reverse: assuming that because one thing did not cause an effect, nothing did. And the single-cause version: the argument names one cause and ignores every other possible cause.
An LSAT-style example
This example is original. It is not a real LSAT question.
Towns that installed traffic cameras saw speeding tickets rise 30 percent. Therefore, traffic cameras cause drivers to speed more.
The flaw: The rise in tickets could mean more speeding, or it could mean the cameras simply catch speeders who were already there. The argument treats a correlation as proof of causation.
How to spot it on test day
- Look for a conclusion with causal language: "causes," "leads to," "is responsible for," "is the reason."
- Check the evidence: is it just two things happening together, or a survey, or a before-and-after?
- Ask: what else could explain this? If you can name one alternative in five seconds, it is probably a causation flaw.
The right answer vs. the trap
The right answer
Usually "mistakes a correlation for a cause" or "overlooks the possibility that the effect has another cause." Abstract wording, no details from the argument.
The trap
"The argument assumes the survey sample was too small." Only pick a sampling answer if the argument actually relies on a survey or sample. Causation flaws get sampling traps because both involve weak evidence.
Find your weak flaws
The free diagnostic scores flaw questions separately and shows whether this pattern is costing you points.