Assumptions in Causal Arguments

An anthropologist studied several isolated farming communities in the Andean highlands. The study revealed that communities primarily cultivating a specific heirloom variety of quinoa have significantly lower rates of cardiovascular disease than neighboring communities that cultivate standard commercial crops. Based on this observation, the anthropologist concluded that consuming this heirloom variety of quinoa provides unique protective benefits for cardiovascular health.

Which of the following are necessary assumptions required by the anthropologist's argument? (Select all that apply.)

Linguists analyzing the evolution of indigenous languages in the isolated Solenoid Archipelago observed that languages spoken by coastal fishing communities have an unusually high rate of phonetic simplification (the dropping of complex consonant clusters) compared to the languages of inland agricultural communities. The linguists also noted that when a massive seismic event forced several coastal communities to relocate inland a century ago, their languages quickly ceased undergoing phonetic simplification. The linguists hypothesize that the constant ambient noise of crashing ocean waves inherently degrades the oral transmission of complex phonetic structures, thereby causing these languages to simplify over time.

Which of the following are necessary assumptions upon which the linguists' hypothesis depends? Select all that apply.

A ten-year ecological study of the Silver-tufted Macaque found that troops living in regions with high concentrations of naturally occurring lithium in the water supply exhibit significantly lower rates of aggressive intra-troop conflicts compared to troops living in lithium-poor regions. Based on this observation, the researchers concluded that the consumption of lithium-rich water reduces aggressive behavior among these macaques.

Which one of the following is an assumption on which the researchers' argument depends?

Last year, the city government installed a 'smart' traffic light system designed to prioritize pedestrian crossings on its primary downtown commercial avenues. In the twelve months since the installation, retail businesses located along these avenues have reported a 30 percent increase in pedestrian foot traffic and a correspondingly significant rise in sales. A city planner concludes that the new traffic light system directly caused this increase in downtown commercial activity by making the avenues substantially more pedestrian-friendly.

Which of the following are necessary assumptions upon which the city planner's argument depends? Select all that apply.

Researchers analyzing sediment cores from Lake Voltonia have identified a precipitous drop in the concentration of pollen from domesticated cereal crops dating precisely to the early 14th century. Historical archives from the surrounding region indicate that a severe, prolonged economic depression began during the exact same period. Based on this correlation, the researchers conclude that the economic depression must have triggered a mass abandonment of agricultural lands, which in turn caused the observed reduction in cereal crop pollen.

Which of the following is an assumption on which the researchers' argument depends?

A recent study of adult diets revealed that individuals who drink at least one cup of green tea daily have a significantly lower incidence of heart disease compared to those who do not drink green tea. The researchers concluded that consuming green tea actively protects against the development of heart disease.

Which of the following are necessary assumptions upon which the researchers' causal argument depends? (Select all that apply)

Researchers recently observed that office workers who regularly consume green tea report experiencing significantly lower levels of daily stress than those who do not. Furthermore, among the workers observed, those who consume the greatest amount of green tea report the lowest stress levels. The researchers conclude that the antioxidants present in green tea act directly on the nervous system to reduce stress.

Which one of the following is an assumption on which the researchers' argument depends?

Match each causal argument below to the specific category of necessary assumption it fundamentally relies upon.

Match each of the following causal arguments (Left) with the specific unstated assumption upon which its conclusion most heavily relies (Right).

In a recent study of elementary school students, researchers found that children who play a musical instrument score significantly higher on math tests than children who do not. Based on this finding, the researchers concluded that learning to play a musical instrument improves a child's mathematical ability.

Which one of the following is an assumption required by the researchers' argument?

Paleontologists have excavated a dense concentration of Bactrosaurus fossils in a single geological stratum dating to a period immediately following a colossal volcanic eruption. Volcanic ash contains extremely high levels of fluorine, and ingesting large quantities of fluorine causes acute, fatal bone toxicity in large herbivores. Based on this evidence, the paleontologists concluded that these dinosaurs perished from fluorine poisoning contracted by grazing on vegetation blanketed by the volcanic ash.

Which one of the following is an assumption on which the paleontologists' argument depends?

Historians analyzing ancient Mesopotamian city-states have noted that eras of significant architectural expansion consistently coincide with periods when a city-state's primary currency—a standardized grain measure—was widely circulated. Based on this correlation, the historians conclude that the implementation of a standardized currency directly stimulated the economic prosperity necessary to fund such massive architectural endeavors.

Which one of the following is an assumption on which the historians' argument depends?

A multi-decade study of the Silver-tufted Macaque, a primate species inhabiting both dense rainforests and newly established agricultural plantations, revealed a striking trend: macaques living in the plantation zones exhibit significantly lower levels of the stress hormone cortisol than their rainforest counterparts. The researchers noted that plantation environments lack the large arboreal predators common in the rainforest. Therefore, the reduced presence of these natural predators in the plantations has caused the lower cortisol levels observed in the plantation macaques.

Which one of the following is an assumption upon which the argument depends?

Below are four distinct arguments that conclude a causal relationship based on observed evidence. For each argument, identify the specific logical gap it leaves open by matching it to the core assumption necessary to bridge that gap.

Agronomists observing wild varieties of the montane scrub-oak have discovered that trees growing on the northern slopes of the Oakhaven range produce acorns with significantly thicker shells than those growing on the southern slopes. Over the last century, the northern slopes have experienced a steady increase in the population of the red-crested woodpecker, a bird that occasionally bores into acorns to extract nutrients. Since the red-crested woodpecker population has remained negligible on the southern slopes, the agronomists conclude that the increased presence of these woodpeckers has driven the evolutionary adaptation of thicker acorn shells in the northern scrub-oaks.

Which of the following are assumptions upon which the agronomists' argument depends? (Select all that apply)

Ten years ago, the government of Valoria eliminated all tariffs on imported industrial machinery. In the decade since this policy change, Valoria's domestic manufacturing output has grown by 50 percent, and the average age of the industrial machinery used in Valorian factories has decreased by exactly five years. Economists have concluded that the tariff elimination caused the surge in manufacturing output by enabling factories to affordably replace outdated equipment with newer, more efficient imported machinery. Which one of the following is an assumption required by the economists' argument?

Match each causal argument with the specific category of assumption required for its conclusion to logically follow.

Marine biologist: In the coastal waters of the Vespian Sea, significant increases in the ghost jellyfish population consistently occur shortly after periods of unusually heavy rainfall. Heavy rainfall washes large quantities of agricultural runoff into the sea, resulting in massive blooms of phytoplankton. Because phytoplankton is the primary food source for ghost jellyfish, we can conclude that these phytoplankton blooms are the cause of the periodic surges in the jellyfish population.

Which one of the following is an assumption on which the marine biologist's argument depends?

A recent study of manufacturing firms revealed that those adopting AI-driven predictive maintenance on their assembly lines experienced a 30 percent reduction in unexpected equipment failures over two years, compared to firms relying on traditional scheduled maintenance. The analysts conducting the study concluded that the AI software directly causes this reduction by detecting microscopic wear and tear before it leads to critical breakdowns.

The analysts' argument depends on assuming which one of the following?

Identify the specific logical gap present in each scenario by pairing the causal argument with the unstated premise required for its conclusion to hold true.