Match each of the following arguments with the underlying unstated assumption that is strictly required for its conclusion to be logically justified.
- Cognitive Scientist: Monolingual infants lose sensitivity to non-native phonetic contrasts by their first birthday, whereas bilingual infants maintain sensitivity to contrasts in both languages beyond twelve months. Therefore, early multilingual speech exposure directly prevents the neural pruning of auditory discrimination pathways.The prolonged phonetic discrimination exhibited by bilingual infants does not reflect a generalized developmental delay in auditory neural maturation.
- Agronomist: Coffee farms transitioning from open-field monocultures to canopy-shaded agroforestry systems decreased synthetic nitrogen fertilizer applications by forty percent over five years with no drop in crop yield. Thus, the shade trees' fallen foliage and root systems supply the nitrogen needed to replace the synthetic fertilizer.The reduced requirement for synthetic fertilizer in shaded plots was not primarily caused by increased soil moisture retention improving the absorption efficiency of residual nutrients.
- Dendrochronologist: Subpolar larch tree rings from the mid-sixth century exhibit three consecutive years of exceptionally narrow, low-density wood cells—a structural deformity observed in living larches exclusively during severe summer temperature drops. Hence, a major climate-cooling event occurred during those three years.The low-density cellular anomalies found in the mid-sixth-century larch rings were not the result of non-climatic biological disturbances such as severe defoliating insect infestations.
Answer
The cognitive scientist's argument matches the assumption regarding the absence of generalized auditory developmental delays; the agronomist's argument matches the assumption regarding soil moisture and nutrient absorption efficiency; and the dendrochronologist's argument matches the assumption ruling out non-climatic insect defoliation disturbances.
Each correct pairing links an argument to a defender assumption that eliminates an unaddressed alternative explanation. For the cognitive science argument, ruling out a developmental maturation lag ensures the retained sensitivity is an effect of language exposure. For the agricultural argument, ruling out moisture-enhanced uptake of residual nutrients ensures the trees themselves are providing the nutrient substitute. For the dendrochronology argument, ruling out insect infestations ensures that ring deformities can be uniquely attributed to low temperatures.
Step-by-Step Solution
Key Concept
Necessary Assumption (Defender Assumption & Negation Test)
Estimated Time:1m 30s