Historian: The sudden abandonment of the ancient city of Kaelen was triggered by either a prolonged drought, a severe plague, or a military invasion. Geological records demonstrate that the region experienced above-average rainfall during that century, ruling out drought. Furthermore, excavations have revealed no mass graves or biological indicators of disease typical of a plague. Consequently, a military invasion must have been the cause of the city's abandonment.
Which of the following arguments is most similar in its pattern of reasoning to the historian's argument?
- Astronomer: The anomaly in the star's light curve is due to an exoplanet transit, a massive sunspot, or a dust cloud. The star's spectral lines show no magnetic disturbances typical of sunspots, and infrared observations definitively rule out a dust cloud. Thus, an exoplanet must be transiting the star.Answer
- BDetective: Most successful bank robberies are inside jobs, require sophisticated hacking, or involve heavily armed teams. The recent robbery was not carried out by an armed team, nor was there any sign of hacking. Therefore, it is highly likely that the robbery was an inside job.
- CArchaeologist: The destruction of the Kaelen artifact was due to deliberate vandalism, accidental dropping, or natural weathering. The artifact was found shattered near the entrance, a location heavily frequented by looters. Given this evidence, deliberate vandalism is the definitive cause of its destruction.
- DPolitician: If a public policy is successful, it must have bipartisan support, adequate funding, or strong public approval. The new education policy has adequate funding and strong public approval. Therefore, it will undoubtedly be a successful policy.
- EBiologist: The decline in the local amphibian population is the result of chemical runoff, habitat destruction, or an invasive predator. The population decline coincided exactly with the introduction of a non-native snake species. Therefore, an invasive predator must be the cause of the decline.
Answer
The argument concerning the astronomer, which concludes an exoplanet is transiting the star after ruling out a sunspot and a dust cloud.
The stimulus presents a flawless argument by elimination. It first establishes that exactly one of three possible causes (drought, plague, or military invasion) must be responsible for a phenomenon (the abandonment of the city). It then provides evidence to systematically rule out two of those possibilities (drought and plague). Finally, it concludes with absolute certainty that the remaining possibility (military invasion) must be the cause. The correct choice perfectly mirrors this logical structure: it lists three possible causes for an anomaly, rules out two of them using specific evidence, and concludes that the third must be the true cause.
Step-by-Step Solution
Key Concept
Argument by Elimination (Disjunctive Syllogism)