Passage

After the town installed new streetlights, reported thefts fell. Therefore, the streetlights caused the reduction in theft.

Question

Which fact most weakens the conclusion?

Answer

The town also began nightly police patrols during the same period.

Solution

1. The argument treats the timing of two events as proof of causation.
2. Nightly patrols provide another plausible cause for the fall in theft.
3. That alternative explanation weakens the claim about streetlights.