LSAT Explanation PT 23, S2, Q19: Even in ancient times, specialized farms

LSAT Question Stem

Which one of the following is an error of reasoning in the argument? 

Logical Reasoning Question Type

This is a Flaw 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 presents the following premises and conclusion:

Premise 1: Specialized farms existed only where there were large commercial markets for farm products, which presuppose urban populations.

Premise 2: The land in the region of Kadshim could only have supported mixed farms.

Conclusion: The extensive ruins at Kadshim are probably the remains of a largely uninhabited ceremonial structure rather than a densely populated city.

The argument's structure involves a mistaken negation of the relationship between specialized farms and urban populations. It assumes that because there were no specialized farms in Kadshim, there must not have been a densely populated city. This is a flaw in the reasoning.

The question type for this problem is a Flaw question, asking us to identify the error of reasoning in the argument.

Now, let's discuss each answer choice:

a) The argument does not generalize from an observed sample to a larger population. The flaw is not about improper generalization, but rather the mistaken negation of the relationship between specialized farms and urban populations.

b) This is the correct answer choice. The argument takes the nonexistence of specialized farms as evidence that a necessary precondition for them (urban populations) also did not exist. This is a mistaken negation of the relationship between specialized farms and urban populations.

c) The argument does not involve interpreting an ambiguous claim in different ways in different parts of the argument. The flaw is about the mistaken negation of the relationship between specialized farms and urban populations, not about equivocation.

d) The argument does not make a causal claim based on evidence of correlation. It does not state that urban populations cause specialized farms or vice versa, only that the former is necessary for the existence of the latter. The flaw is in the mistaken negation of this relationship.

e) The argument does not make a circular argument. Its conclusion is not simply a restatement of its premises. The flaw is in the mistaken negation of the relationship between specialized farms and urban populations, not in circular reasoning.

In conclusion, the correct answer choice is (b) because it identifies the flaw in the argument as taking the nonexistence of specialized farms as evidence that a necessary precondition for them (urban populations) also did not exist. This is a mistaken negation of the relationship between specialized farms and urban populations.