LSAT Explanation PT 45, S4, Q19: According to some astronomers, Earth is

LSAT Question Stem

The reasoning in the argument is most subject to criticism on the grounds that the argument 

Logical Reasoning Question Type

This is a Flaw question. 

Correct Answer

The correct answer to this question is C. 

LSAT Question Complete Explanation

The question type for this problem is a Flaw question, which asks us to identify the flaw in the argument's reasoning.

Let's first break down the argument and label each part as either a premise or a conclusion:

1. Premise: According to some astronomers, Earth is struck by a meteorite large enough to cause an ice age on an average of once every 100 million years.

2. Premise: The last such incident occurred nearly 100 million years ago.

3. Sub-conclusion: So, we can expect that Earth will be struck by such a meteorite in the near future.

4. Main Conclusion: This clearly warrants funding to determine whether there is a means to protect our planet from such meteorite strikes.

The problem with this argument is that it uses an average frequency of an event (meteorite strikes) to make a specific prediction about when the next event will occur. To illustrate this flaw, imagine a person who flips a coin and gets heads five times in a row. Just because the average outcome is 50% heads and 50% tails, it doesn't mean that the next flip will definitely be tails. The past flips do not affect the probability of future flips.

Now, let's evaluate the answer choices:

a) This answer choice is incorrect because the argument does not establish a high probability for a disastrous event. It only provides information about the average frequency of meteorite strikes.

b) This answer choice is also incorrect because the argument actually assumes that the probability of a meteorite strike is affected by the time since the last strike, not that it is unaffected.

c) This answer choice is correct because it identifies the flaw in the argument: moving from evidence about the average frequency of an event to a specific prediction about when the next such event will occur.

d) This answer choice is incorrect because the likelihood of a meteorite causing an ice age is not the main flaw in the argument. Even if the likelihood is low, there could be other consequences of a meteorite strike that warrant funding for protection measures.

e) This answer choice is incorrect because the argument does not presume that a feasible means to deter large meteorite strikes can be found. It only suggests that we should investigate the possibility of protecting Earth from such strikes.