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Zorluk: OrtaNecessary Assumption

Economist: A municipal transit authority recently introduced dynamic fare pricing on its subway lines, increasing ticket prices during morning peak hours while substantially discounting fares immediately before and after the rush period. Over the following six months, train overcrowding during the morning peak period fell by 18 percent. Because total daily subway ridership remained unchanged across the system over this six-month period, transit officials concluded that the pricing differential successfully caused a substantial portion of peak-hour commuters to shift their travel to off-peak hours.

Which of the following are assumptions on which the transit officials' argument depends? (Select all that apply.)

  1. The reduction in morning rush-hour overcrowding was not primarily achieved by increasing train capacity or service frequency during peak periods.Cevap
  2. B
    Discounting off-peak fares is a more potent incentive for altering commuter behavior than increasing peak-hour fares.
  3. The stable daily ridership figures were not produced by peak commuters abandoning the subway entirely while an equivalent number of new passengers adopted off-peak travel.Cevap
  4. D
    Most commuters who regularly ride the subway during peak hours possess flexible employment schedules that permit shifting their work hours.
  5. E
    Prior to the pricing change, none of the morning peak-hour commuters were wealthy enough to remain completely unaffected by fare increases.

Cevap

The argument depends on assuming that the drop in peak overcrowding was not caused by increased train capacity or frequency, and that total ridership stability was not caused by peak riders exiting the subway system while new off-peak riders replaced them.
The conclusion asserts that the fare structure caused commuters to change their travel times, relying on two pieces of evidence: reduced peak overcrowding and unchanged overall ridership. For this conclusion to be valid, the argument must assume that peak overcrowding was not simply alleviated by expanding train service capacity (which would mean rider schedules never changed), and that the unchanged total ridership was not an artifact of peak commuters leaving the subway system while new passengers took off-peak trains (which would mean existing riders did not shift schedules). Negating either requirement directly refutes the claim that peak-hour commuters shifted to off-peak travel.

Adım Adım Çözüm

1
Analyze the premises and the conclusion of the stimulus.
Premises: Dynamic pricing was implemented (peak surcharges, off-peak discounts); peak overcrowding dropped by 18 percent; total daily ridership remained constant. Conclusion: The fare differential shifted a substantial portion of peak commuters to off-peak travel times.
Identifying the core inferential leap is essential for locating unstated assumptions that must hold true for the conclusion to follow from the premises.
2
Evaluate potential Defender assumptions that rule out competing explanations for the observed data.
Two rival explanations must be blocked: (1) an operational increase in train frequency/capacity causing the 18 percent crowding reduction, and (2) commuter turnover where peak riders quit the subway and new off-peak riders joined.
A necessary assumption must protect the causal link from plausible confounding factors that would otherwise explain the evidence without supporting the conclusion.
3
Apply the Negation Test to identify which statements fatally undermine the conclusion when negated.
Negating the statement regarding train capacity shows that overcrowding dropped without any commuter shifts. Negating the statement regarding commuter turnover shows that peak riders did not move to off-peak slots. Both negations destroy the conclusion.
Any statement whose logical negation invalidates the argument is strictly necessary to the logic.

Anahtar Kavram

Necessary Assumption in Causal and Explanatory Arguments
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Konular

Necessary Assumption

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