Logical reasoning PrepTest 154 · Section 4 · Question 23

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Talking on your phone while driving is more dangerous than talking to someone who's actually in the car with you, says a safety expert. The person in your phone can't tell when your driving situation suddenly becomes difficult. The person in your car, on the other hand, would stop talking in such a situation or might provide helpful warnings.

Answer Anticipation:
What's missing here is a tie from the described behaviors to "more dangerous." Is it actually more dangerous to have the person you're talking to fail to respond to a difficult driving situation? According to this argument, we don't really know. If a conversational partner's response (or lack thereof) to difficult driving situations doesn't change the level of danger, this argument fails.

Answer Explanation:
Right up front! Negate this and you get " . . . does not significantly increase the risk," which, if true, would destroy the entire argument. If continuing to speak to the driver doesn't make an accident more likely, then the continued speaking of a person on a cell phone during a difficult driving situation could not by itself make using a cell phone more dangerous than talking to a passenger in the vehicle.

Key Takeaway:
Specificity is key. When comparing two things, in this case the relative danger level of cell phone conversations and passenger conversations, avoid answer choices that bring in unrelated phenomena, like drivers' perceptions of what's safe when driving. Strengthen with Necessary Premise will be meaningfully related to the phenomena being compared in the stimulus.

Incorrect. We're not comparing talking on a cell phone to not talking at all in this argument. This is only about talking on the phone vs. talking to a passenger.

Incorrect. It doesn't matter what the drivers believe! The safety expert is talking about an objective observation, how dangerous an activity is. Unless a rule tells us "driving is only as dangerous as the driver perceives it to be," their perception doesn't matter.

Incorrect. If this were true it would hurt the argument, so negating it actually helps the argument. That's the opposite of the criteria for a Strengthen with Necessary Premise (i.e., Necessary Assumption). This is more like an Unnecessary Assumption (that's not a thing).

Incorrect. This would be an interesting follow-up test to get more information on how dangerous cell phones are, but it's not a necessary assumption. Negate it and it's still too weak to affect the argument, because, in practice, we already know that passengers do not tend to continue talking during a difficult driving situation.