This blog post was written by guest author Kevin of Getdegrees.com. Thank you Kevin!
I once heard a U.S. anti-counterfeiting expert speak about his craft: “My men don’t study counterfeit bills. I train them to know and love the real thing, so that the slightest flaw is obvious.” This is a romantic sentiment, and the phrase sounds like something Matt Damon would say in a film. The implication for performing well on the logical reasoning section of the LSAT is that you don’t need to identify all the different ways an argument can go wrong. Studying how valid arguments are structured could help make invalid arguments seem ludicrous, and there’s something to be said for this strategy. Unlike false bills, however, false arguments have catchy names you can toss around when accusing people of faulty logic.
Below are a few arguments that appear often enough on the LSAT, and in real life, to justify learning.
Ad Hominem
Is someone passing around bad arguments? Save the name-calling until after you’ve shamed him with good logic. If your only evidence for discrediting an opponent is his bad reputation, you’re engaging in an ad hominem attack. Just because someone is a hypocrite, a criminal or a general “so-and-so” does not guarantee that his statements are false.
On the LSAT (PrepTest 32)
Editorial: The premier’s economic advisor assures her that with the elimination of wasteful spending the goal of reducing taxes while not significantly decreasing government services can be met. But the premier should not listen to this advisor, who in his youth was convicted of embezzlement. Surely his economic advice is as untrustworthy as he is himself, and so the premier should discard any hope of reducing taxes without a significant decrease in government services.
Argumentum Ad Populum
“But everybody’s doing it,” you said, during that month in 2002 when all of your friends got perms. If only you had soberly listed the benefits of resiliently wavy hair, your parents might have set up the salon appointment. Instead, they were dubious of your appeal to the people, and you had to answer the same old question about peer pressure and jumping off a bridge.
On the LSAT (PrepTest 28):
Political commentators see recent policies of the government toward Country X as appeasement, pure and simple. This view is fundamentally mistaken, for polls show that most people disagree with the political commentators’ assessment of government policies toward Country X.
Straw Man
Imagine that the Revolutionary War took place between American colonists and heaps of straw stuffed into red uniforms. Despite the musket injuries to pounds and pounds of threshed grain, the real British army would have no reason to feel defeated. Likewise, disputing a misrepresented version of your opponent’s argument is a really cheap move. In the example below, the dean distorts the student representative’s argument by equating a failure to expel someone for a behavior with an endorsement of that behavior.
On the LSAT (PrepTest 7):
Student representative: Our university, in expelling a student who verbally harassed his roommate, has erred by penalizing the student for doing what he surely has a right to do: speak his mind!
Dean of students: But what you’re saying is that our university should endorse verbal harassment. Yet surely if we did that, we would threaten the free flow of ideas that is the essence of university life.
Begging the Question
A statement should never serve as both a premise and a conclusion, otherwise you’re arguing in a circle. “How do I know that my girlfriend never lies to me? Well, she told me that she always tells the truth.” Let neither the test nor two-faced significant others play you like a fool!
On the LSAT (PrepTest 49)
Commentator: Human behavior cannot be fully understood without inquiring into nonphysical aspects of persons. As evidence of this, I submit the following: suppose that we had a complete scientific account of the physical aspects of some particular human action—every neurological, physiological and environmental event involved. Even with all that we would obviously still not truly comprehend the action or know why it occurred.