LSAT Explanation PT 41, S3, Q7: In Western economies, more energy is

LSAT Question Stem

On which one of the following assumptions does the argument rely? 

Logical Reasoning Question Type

This is a Necessary Assumption question. 

Correct Answer

The correct answer to this question is A. 

LSAT Question Complete Explanation

Let's first analyze the argument in the passage. The passage states that in Western economies, more energy is used for buildings than transportation. It also mentions that since the oil crisis of 1973, there has been a decline in energy consumption due to more efficient use of energy in homes and offices. New building technologies have led to billions of dollars in energy savings. The conclusion of the argument is that 50 to 100 years from now, these energy savings will amount to more than $200 billion per year (in current dollars).

To better understand the passage, let's use a simple example. Imagine a city where the energy used for lighting, heating, and ventilation in buildings is more than the energy used for transportation. Over the years, the city has adopted energy-efficient technologies that have reduced energy consumption and saved money on energy bills. The argument claims that in the future, these savings will be even more significant.

An "Evaluate" question for this argument could be: "Will the cost of energy-efficient technologies remain affordable in the future?"

The question type of this problem is Necessary Assumption, which asks us to identify the assumption on which the argument relies. Let's discuss each answer choice:

a) Technology used to make buildings energy efficient will not become prohibitively expensive over the next century.

This is the correct answer. The argument assumes that energy-efficient technologies will continue to be affordable and accessible in the future, leading to increased savings. If these technologies were to become prohibitively expensive, it could undermine the conclusion that energy savings will increase in the future.

b) Another oil crisis will occur in the next 50 to 100 years.

This assumption is not necessary for the argument. The oil crisis of 1973 is mentioned as a historical event that contributed to the decline in energy consumption, but the argument does not rely on the occurrence of another oil crisis to support the conclusion.

c) Buildings will gradually become a less important consumer of energy than transportation.

This assumption is not necessary for the argument. The passage states that buildings currently use more energy than transportation, but the conclusion about future energy savings does not depend on buildings becoming a less important consumer of energy.

d) Energy bills in the West will be $200 billion lower in the next 50 to 100 years.

This answer choice is incorrect because it misrepresents the conclusion. The conclusion states that energy savings will amount to more than $200 billion per year, not that energy bills will be exactly $200 billion lower. Additionally, energy bills could still be higher in the future even with the energy savings, due to factors like inflation or increased energy consumption in other areas.

e) Energy-efficient technologies based on new scientific principles will be introduced in the next 50 to 100 years.

This assumption is not necessary for the argument. The argument is based on the current energy-efficient technologies and their impact on energy savings. While new technologies could potentially contribute to future savings, the argument does not rely on their introduction to support the conclusion.