Question

Difficulty: MediumIdentifying Unstated Assumptions

In an effort to reduce carbon emissions from corporate travel, management at Veloce Strategy announced a policy requiring all employees traveling distances under 300 miles to take passenger trains instead of commercial flights. Company executives project that this policy will reduce the firm's total annual travel-related carbon footprint by at least 15 percent, noting that short-haul flights currently account for 20 percent of Veloce's travel emissions and that electric passenger rail produces negligible direct emissions.

Which of the following is an assumption on which the executive's projection depends?

  1. A
    Passenger rail travel for journeys under 300 miles is consistently less expensive per employee than booking short-haul commercial flights.
  2. Employees subject to the new policy will not choose to drive personal gasoline-powered automobiles for a significant portion of their business trips under 300 miles.Answer
  3. C
    Short-haul flights of under 300 miles produce more carbon emissions per passenger-mile than long-haul international flights.
  4. D
    The passenger rail network connecting cities under 300 miles apart will experience major service delays over the coming year.
  5. E
    Veloce Strategy will completely offset its remaining travel-related carbon emissions by purchasing environmental credits within five years.

Answer

The correct option is the statement that employees subject to the new policy will not choose to drive personal gasoline-powered automobiles for a significant portion of their business trips under 300 miles.
The argument relies on the premise that eliminating short-haul flights (which constitute 20% of emissions) by mandating electric rail will yield a net reduction of at least 15%. For this projection to hold, employees must not replace flights with another carbon-intensive transport method, such as driving gasoline-powered vehicles. If employees were to drive instead, the resulting auto emissions would offset the savings from avoiding short-haul flights, causing the conclusion to collapse.

Step-by-Step Solution

1
Identify the premises and conclusion of the argument
Premises: Short-haul flights account for 20% of emissions; electric rail produces negligible emissions. Conclusion: Replacing short-haul flights with train travel will reduce total travel emissions by at least 15%.
Deconstructing the argument reveals the gap between shifting away from short-haul flights and achieving the net 15% reduction.
2
Identify the potential logical gap
The author assumes that employees banned from flying under 300 miles will actually take the train rather than substituting flights with another high-emission transport mode (such as gasoline cars).
If employees substitute flights with driving cars, new emissions from driving could negate the expected savings.
3
Apply the Negation Test to confirm the necessary assumption
Negated statement: 'Employees WILL choose to drive personal gasoline-powered automobiles for a significant portion of these trips.' If true, emissions from driving would rise, destroying the claim that emissions will drop by at least 15%.
Since the negated choice shatters the main conclusion, it is a required unstated assumption.

Key Concept

Identifying Unstated Assumptions via the Negation Test
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