Logical reasoning PrepTest 137 · Section 4 · Question 2

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
The "Clean City" campaign was implemented, and the streets are cleaner, so the campaign must have worked!

Answer Anticipation:
Whenever an argument claims that something worked, it's drawing a causal conclusion that will frequently be based on a correlation. And that's what happened here—the campaign was implemented, and the streets are cleaner now, so the campaign must have worked.

As with any correlation/causation jump, the argument is assuming a few things:
(1) No other cause can explain the effect (e.g., an increase in government spending on clean-up programs)
(2) This wasn't a coincidence (rarely correct on the LSAT)
(3) The relationship isn't reversed (this doesn't make sense here because of the timeline)

The correct answer will likely eliminate at least one other cause/explanation for the decrease in the amount of trash on the streets.

Answer Explanation:
While this answer doesn't speak to a specific alternative cause, it does suggest that there wasn't one by highlighting that the effect wasn't present without the supposed cause. If the trend was towards more cleanliness on the city streets before the campaign was started, then whatever was driving that change could explain the increased cleanliness after the campaign, killing the argument.

Key Takeaway:
When a Strengthen with Necessary Premise question has an argument with a correlation/causation flaw, the most likely correct answer is one that eliminates an alternative cause. Sometimes, however, it'll do so indirectly, as it did here, and one method to do that is to highlight that the effect wasn't present before the effect. If that sounds like a common correct answer in a baseline Strengthen question, great catch!

Incorrect. The argument doesn't require the opposing point to believe anything since the conclusion is about whether the campaign worked, not what other people think.

Incorrect. The campaign doesn't need to be more effective to be a rousing success. This comparative answer would only be necessary if it were established that other campaigns weren't a rousing success.

Incorrect. The funding of the campaign is out of scope.

Incorrect. The argument doesn't require a steady decline in trash—if there was an initial burst followed by a slower decline, or a slow ramp-up, the argument could still hold true.