LSAT 123 | Section 2 | Logical Reasoning: Q5

LR Question 5 Explanation

QUESTION TEXT: Scientist: Earth’s average annual temperature has increased…

QUESTION TYPE: Weaken

CONCLUSION: The 0.5 degree celsius warming was caused by larger amounts of minor gases in the atmosphere.

REASONING: Minor gases prevent heat from leaving the planet.

ANALYSIS: This argument seems plausible. There would be two ways to weaken it:

• Showing that minor gases aren’t significant enough to account for 0.5 degrees of warming.
• Showing that some other factor is a more likely cause of the 0.5 degrees of warming.
• Showing that the minor gases can’t have been the cause, for some other reason.

___________

1. The scientist didn’t mention pollution. The source of the gases is irrelevant to her argument.
    
   This answer is trying to trick you by making you think of outside facts involving pollution and global warming. But the gas could be released by nature, for example.
2. CORRECT. This works. It shows that the proposed cause and the effect occurred at different times. So it’s likely something else caused the warming.
3. This is irrelevant. 0.5 degrees warming is a lot. It’s unlikely that “slightly” more solar radiation could be the cause. And the argument is referring to the average annual temperature over time – an average can go up or down in some years while still rising overall. (This answer just says certain years received more radiation. It didn’t say every year did.)
4. The argument is about a change in the atmosphere and a change in temperature. This answer doesn’t say that volcanic dust and particles have increased or decreased during the past century.
5. This supports the argument somewhat. If there was an unusually large increase in minor gases then that increases their potential warming effect.