PrepTest 107

Incorrect. Charles' argument is about the people who were employed but now aren't due to the increase in unemployment, so those who never had a job are out of scope. Even if this group drives a bit more frequently, the decrease from those who had jobs could more than offset it.

Incorrect. First, this answer is about the majority of air pollution, not the majority of air pollution due to automobiles—a subtle shift that means it's not directly speaking to the conclusion. Regardless, even if those driving to work make up a significant minority of automobile air pollution, that total could still go down if there are fewer people driving to work.

Incorrect. Similar to (B), even if most people do use public transportation to work, the individuals who drive could see their air pollution contribution go down when they lose their jobs.

Correct. Argument or Facts:
Argument/Argument

Valid or Flawed:
Flawed/Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
C: In a recession, unemployment goes up, so fewer people are driving to work, and so pollution due to car exhaust goes down.

D: People can't afford new cars, and old cars pollute more, so there's no reason to think pollution will go down.

Answer Anticipation:
This question asks about Charles' argument, so we should focus there to find any gap in the argument.

Charles' argument has a lot of causality in it, and it attempts to use that to predict the outcome of a given change. If a recession happens, unemployment will generally go up. If fewer people have jobs, then fewer people will be driving to their jobs. From this, Charles concludes that fewer polluting cars will be on the road, and thus pollution should go down.

Whenever a conclusion talks about the overall balance of something—here, both cars on the road and pollution in the air—it's important to see if the premises speak to all contributing factors. And here, they don't, on either front.

First, driving to work isn't the only place people drive to. Just because fewer people are driving to work doesn't mean there are fewer cars on the road. Maybe those people fill up their days by driving even more, bouncing job interviews or errands. Charles assumes that if people aren't driving to work, they aren't driving.

Second, as highlighted by Darla, fewer cars on the road doesn't necessarily mean less pollution. It could be, as Darla states, that the cars on the road pollute more. Charles is assuming that the number of cars on the road determines the pollution rate, not something specific about those cars.

Either of these answers can be correct, but let's also be wary of one potential incorrect answer—that people who aren't driving might be polluting through other means, such as consuming more electricity (TV, PS5, etc . . . ). The conclusion of Charles' argument is about pollution "due to automobile exhaust," so other sources of pollution are out of scope.

Answer Explanation:
This answer highlights the first assumption that we pointed out. Charles assumes that if people aren't driving to work, they aren't driving. However, they could be driving to other places—interviews, errands, the park. If the reduction of people driving to work is offset by increased use for other reasons, then the argument falls apart.

Key Takeaway:
Whenever an argument shows that one factor in a broad category decreases and concludes that the category overall decreases, it's assuming that none of the other factors increase to "make up" for the decrease. However, that's always possible—as we saw here, people who aren't driving to work might be driving elsewhere.

Incorrect. Similar to (B) and (C), even if the commuters are in the minority (of whatever subset, no matter how you slice it), that group driving less could contribute to a significant reduction in air pollution due to car use.