Logical Reasoning

Below are five short arguments concerning the proposed Arcadia transit expansion. Each argument is logically incomplete because it commits a formal reasoning error or lacks a crucial premise. Match each incomplete argument to the specific sufficient assumption that perfectly bridges its logical gap.

Legal scholar: A judicial ruling cannot be considered legally definitive unless it relies upon settled case law or explicitly overturns prior interpretive frameworks. We know that any ruling explicitly overturning prior interpretive frameworks inevitably destabilizes market expectations. The recent appellate decision regarding digital asset property rights clearly did not destabilize market expectations. Therefore, the recent appellate decision cannot be considered legally definitive.

The conclusion drawn by the legal scholar follows logically if which one of the following is assumed?

Principle: An academic historian is professionally justified in publishing a controversial historical claim based on newly discovered, unauthenticated documents only if the claim challenges a prevailing consensus that was itself established without rigorous primary source documentation, and the historian explicitly acknowledges the unauthenticated status of these documents. Furthermore, even if the preceding conditions are satisfied, the historian is not justified unless the potential value of the new claim to historical discourse outweighs the risk of disseminating historical inaccuracies.

Which one of the following judgments conforms most closely to the principle stated above?

Marine Biologist: For decades, scientists assumed that the intense bioluminescence of phytoplankton in the Vespera Sea during the summer was simply a physiological byproduct of nutrient-rich deep-ocean upwellings. However, new data reveals that nutrient levels in the Vespera Sea are actually significantly lower in the summer than in the spring, a season when phytoplankton exhibit almost no bioluminescence. Therefore, the summer bioluminescence must be an evolved defensive adaptation against the predatory zooplankton that migrate into the sea during the summer, as these specific predators are known to avoid bright light.

Which of the following, if true, most strongly supports the marine biologist's argument?

Archaeologist: The sudden abandonment of the Xionian urban centers around 1200 BCE is traditionally attributed to a severe regional drought that devastated crop yields. However, recent excavations reveal that the cities' massive grain silos were entirely full when the population fled. Furthermore, isotopic analysis of skeletal remains from that period shows no evidence of nutritional stress. Since the population was clearly not starving, the civilization's collapse must have been precipitated by a sudden military invasion rather than by environmental factors.

Which one of the following, if true, most strongly supports the archaeologist's argument?

Consider the following argument:

Media Scholar: It is widely argued that the mass production of political pamphlets was the primary catalyst for the rapid spread of democratic ideals among the European working class during the 18th century. However, historical records confirm that the literacy rate among this demographic at the time remained firmly below 15 percent. Since the vast majority of these individuals could not read, the diffusion of these revolutionary ideals must have been driven almost entirely by traditional oral communication in public gathering places, functioning completely independent of the printed word.

The media scholar's argument is logically strengthened by newly uncovered historical accounts indicating that 18th-century political pamphlets were regularly read aloud by literate community members to large audiences of illiterate workers in local taverns.