PrepTest 127

Incorrect. Lance lays out a rule, he doesn't make an argument, so he can't be making a circular argument.

Correct. Argument or Facts:
Facts/Argument

Valid or Flawed:
NA/Flawed

Question Type:
Methods of Reasoning

Stimulus Summary:
L: There's an exception to every rule.

F: But that's a general rule which must have an exception, so your rule is wrong.

Answer Anticipation:
Frank uses a common method of reasoning here to rebut Lance's argument—he uses Lance's own logic against him. By showing that Lance's rule applies to his own rule and invalidates it, Frank successfully undercuts that rule.

Answer Explanation:
Frank shows how Lance's rule invalidates itself. If every rule has an exception, then so does that rule—meaning there's a rule out there without an exception! That contradictory implication is used by Frank to invalidate Lance's rule.

Key Takeaway:
Using someone's own logic against them is a common method of reasoning on the LSAT. In fact, there are a few common methods of reasoning, and you should familiarize yourself with them as you practice so that you can get through these questions featuring the common methods more quickly.

Incorrect. Frank only addresses the general rule stated by Lance, so he doesn't show that "no" general rule has exceptions.

Incorrect. While Frank does demonstrate that we shouldn't accept Lance's rule, he doesn't then state that we should accept the opposite rule (that no general rules have exceptions).

Incorrect. Frank highlights the contradiction in Lance's rule, he doesn't invalidate it by showing that it doesn't apply to any real cases. The latter would involve showing that the rule is fine but doesn't apply to any cases; the actual rebuttal states that the rule isn't fine.