LSAT Explanation PT 27, S1, Q11: A local chemical plant produces pesticides

LSAT Question Stem

Which one of the following arguments contains a flaw in reasoning that is similar to one in the argument above? 

Logical Reasoning Question Type

This is a Parallel question. 

Correct Answer

The correct answer to this question is B. 

LSAT Question Complete Explanation

First, let's analyze the argument in the passage. The passage states that a chemical plant produces pesticides that can cause sterility in small mammals like otters. It then notes that after the plant began operating, the incidence of sterility among otters in a nearby river increased dramatically. From this information, the passage concludes that pesticides are definitely contaminating the river. The structure of the argument can be summarized as follows:

Premise 1: Pesticides (X) can cause sterility (Y) in otters.

Premise 2: The plant began operating (Z) and sterility in otters increased.

Conclusion: Pesticides are contaminating the river.

The major flaw in this argument is that it assumes a causal relationship between the two events (the plant operating and otters becoming sterile) based on a correlation (the increase in sterility after the plant began operating). This is known as the "correlation does not imply causation" fallacy.

Now, let's examine the answer choices to identify which one contains a similar flaw in reasoning.

a) This answer choice discusses the relationship between bacteria, tetanus, and horses. However, it does not establish a correlation between two events and then assume a causal relationship, as the original argument does. Instead, it simply states that horses contract tetanus more frequently than other animals due to the presence of bacteria in their digestive tracts.

b) This answer choice parallels the original argument. It states that a low-calcium diet (X) can cause a drop in egg production (Y) in poultry. When chickens on a local farm were let out to forage for food (Z), their egg production dropped. The conclusion is that the food found and eaten by the chickens is undeniably low in calcium. Like the original argument, this answer choice assumes a causal relationship between two events (chickens foraging for food and a drop in egg production) based on a correlation (the drop in egg production after the chickens were let out to forage). Therefore, this is the correct answer.

c) This answer choice discusses the relationship between undernourishment, susceptibility to infection, and animals in metropolitan zoos. However, it does not establish a correlation between two events and then assume a causal relationship. Instead, it negates the conditional statement "undernourished animals are susceptible to infection" to conclude that well-nourished animals are not susceptible to infection. This is a different flaw in reasoning than the original argument.

d) This answer choice discusses the characteristics of apes and the discovery of a fossil with opposable thumbs. It concludes that the fossil must be an ape based on one characteristic (opposable thumbs). This flaw in reasoning is different from the original argument, as it does not assume a causal relationship based on a correlation.

e) This answer choice discusses animal tracks and the presence of bears in a certain area. It concludes that the animal track is fake because there are no bears in the area. This answer choice does not establish a correlation between two events and then assume a causal relationship, as the original argument does. Instead, it presents a conditional relationship (if there are no bears, then the track is fake).

In conclusion, answer choice B contains a flaw in reasoning similar to the one in the original argument, as both assume a causal relationship between two events based on a correlation.