The prior category of flaws dealt with personal insults irrelevant to the argument. Here we describe flaws in argumentation.

1. The Fallacy of Faulty Analogy

Reasoning by analogy functions by comparing two similar things. Faulty Analogy arguments draw similarities between the things that are not relevant to the characteristic in the conclusion.

Argument from Analogy

Premise 1: A and B share properties X and Y
Premise 2: A also has property Z
Conclusion: Therefore, B probably also has Z

Now, let’s look at an example question that revolves around this fallacy.

Mayor of town T decided to lower sales tax in order to boost sales volume. He believes that lowering the tax will increase the sales tax generated since there will be much more total sales volume. The mayor wants to follow the example of town J, where such an experiment helped increase the budget twice in a three-year term.

Which of the following statements is the best proof the opponents of the mayor’s proposal can use in order to persuade the population of town T not to support this decision?

  1. Town J is located very close to the borders of three other states. The sales taxes in those other states are higher than in Town J’s state. This causes residents of other states to shop in town J, to save money. Town T is located far from any state border.
  2. Town T receives only a small portion of its tax receipts from sales taxes. Most taxes come from property taxes and this policy would have no impact on property tax returns.
  3. Town J has many more industrial plants that purchase raw materials from the town’s mines.
  4. This kind of experiment did not work in any other of the six towns that lowered sales tax.
  5. The mayor is corrupted by several groups of residents of town T. These groups are highly interested in lowering the sales tax because it would make them much richer.

Explanation

This is a faulty comparison question where two towns are compared.

  1. This is a non sequitur trap choice. The issue of a city’s tax level has nothing to do with what state you are in. You could just travel from city to city (not state to state) since this is a city tax issue, not a state tax issue.
  2. Although the tax benefit may be small, this does not counter the Mayor’s argument that it would increase tax revenues.
  3. Out of scope.
  4. Correct. Six other examples where this idea didn’t work are a reasonable counterpoint.
  5. Out of scope.

Long-distance runners sometimes get shin splints from over training. Shin splints are also common among freestyle skiers. Therefore, Freestyle skiers must also be guilty of over training.

Which of the following, if true, most weakens the conclusion drawn above?

  1. Sprinters are also prone to getting shin splints.
  2. Freestyle skiers often exhibit other signs of over training such as dehydration
  3. Long-distance runners are less prone to long-term stress injuries
  4. Freestyle skiers get shin splints from landing jumps incorrectly.
  5. Freestyle skiers, on average, train fewer hours than do long distance runners.

Explanation

The passage tells us two facts, one about long-distance runners (they sometimes get shin splints from over training) and one about freestyle skiers (they also get shin splints). The conclusion, that freestyle skiers must also over train, depends on the faulty assumption that because runners’ shin splints are caused by over training, skiers’ must be as well. Choice A is irrelevant. Choice B strengthens the conclusion. Choice C is irrelevant.

Choice D attacks an assumption on which the conclusion depends. If skiers’ shin splints are not caused by over training, then it is not necessarily true that freestyle skiers are guilty of over training. This weakens the conclusion considerably. Choice E seems to weaken the conclusion by suggesting that freestyle skiers may be less likely to over train than runners, but it is, in fact, irrelevant. Choice D is the best answer.

Next LSAT: January 26

2. Straw Man

In a straw man argument, the speaker gives the impression that he or she is refuting an argument made by an opponent. However, the argument being refuted does not represent the opponent’s true position. The arguer is “attacking a straw man”. For instance, a political candidate might argue against “letting all prisoners go free”, attributing that position to his or her opponent, when in fact the opponent simply favors a highly limited furlough system.

The below video captures the essence of the Straw Man fallacy.

The Congressman wants to cut funding for the attack submarine program. I disagree entirely. I do not understand how he can be so irresponsible and leave us defenseless like that.

The congressman just argued for cutting the funding for a specific program. However, the other person is charging that the congressman is “leaving us defenseless”. Clearly, the other person is trying to refute an argument of a Straw Man, not a real person.

You can strengthen a Straw Man argument by showing that the understood argument is not an exaggerated version of the original argument.

The submarine program forms the foundation of our country’s defense system.

You can weaken a Straw Man argument by showing that the understood argument is really an exaggerated version of the original argument.

The assault on the Congressman’s character is far off base. The Congressman knows that the defense budget is finite and prefers spending scarce dollars on more effective defense systems that are unlike the already obsolete attack submarines.

3. Slippery Slope

This argument assumes that if one bad thing happens, then another much worse thing will necessarily happen.

The anti-terrorist laws that monitor international currency transfers, phone calls, and emails are the first step to turning our fragile democracy into a new Nazi regime.

Although infringements of civil liberties are troublesome, it is another argument to suggest infringements of civil liberties will lead to a fascist dictatorship.

The video below explains this fallacy in detail:

John: We should oppose any attempt to register firearms. Such regulation is the first step to confiscation of all weapons and the elimination of our constitutional right to bear arms.

Ted: This is preposterous. Many things in society are registered, such as cars, babies, boats, and lanes, yet these items have never been confiscated.

What are the flaws in the reasoning above?

Explanation

Analysis: Ted is making a faulty analogy between registration of guns and registration of cars and babies. But guns are frequently used as instruments of intentional violence and therefore may be more likely targets for confiscation.

John is making a slippery slope argument that registration of firearms must invariably lead to the elimination of a constitutional right.

4. Begging the Question

Also known as circular reasoning, this is presenting a circular argument in which the conclusion is a premise.

5. The Fallacy of Equivocation

The Fallacy of Equivocation occurs when a word or phrase that has more than one meaning is employed with different meanings throughout the argument.

“Every society is, of course, repressive to some extent – as Sigmund Freud pointed out, repression is the price we pay for civilization.”

-John P. Roche- political columnist

In this example, the word “repression” is used in two completely different contexts. “Repression” in Freud’s mind meant restricting sexual and psychological desires. “Repression” in the second context does not mean repression of individual desires but government restriction of individual liberties, such as that in a totalitarian state.

June 2001 LSAT, S3, Q12

6. The “All Things are Equal” Fallacy


Plus ça change, plus c’est la même chose

(The more things change, the more they remain the same.)

– Jean-Baptiste Alphonse Karr

This fallacy is committed when it is assumed, without justification, that background conditions have remained the same at different times/locations. In most instances, this is an unwarranted assumption for the simple reason that things rarely remain the same over extended periods of time, and things rarely remain the same from place to place.

These questions can be easily spotted because they talk about “last year”, or some past time, and try to create an analogy to predict future events. Over time, however, all sorts of dynamic factors change, so it is difficult to draw direct inferences from past events.

Ten years ago I got a 170 on the LSAT, so I expect to get the same score again.

The last Democrat winner of the New Hampshire primary won the general election. This year, the winner of the New Hampshire primary will win the general election.

The assumption operative in this argument is that nothing has changed since the last primary. No evidence or justification is offered for this assumption.

7. Either / Or Thinking

This is the so-called “black or white” fallacy. Essentially, it says, “Either you believe what I’m saying, or you must believe exactly the opposite.” Here is an example of the black or white fallacy:

Either you are with me or you are against me.

The argument above assumes that there are only two possible alternatives open to us. There is no room for a middle ground.

You can strengthen these arguments by showing that there, generally, is no middle ground. The problem is that most arguments do have a middle ground, meaning that this argument doesn’t work and is very often a fallacy.

October 2001 LSAT S4, Q13
October 2002 LSAT S1, Q1

Middle Ground
Is the opposite of the-claiming that a compromise, or middle point, between two extremes must be the truth.

8. Non Sequitur

This means “does not follow”, which indicates that the conclusion does not follow from the premise. To say, “The house is white; therefore it must be big” is an example. Just because a house is white doesn’t mean that the house must be big.

9. Special Pleading

This is moving the goalposts or making up an exception when a claim is shown to be false. This is similar to shifting the burden of proof.

October 2001 LSAT, S4, Q7

10. Part-to-Whole

This is assuming that one part of something has to be applied to all, or other, parts of it.

June 1996 LSAT, S4, Q3
June 2002 LSAT, S3, Q18
October 2001 LSAT, S4, S18

11. Fallacy of Fallacies

Just because there is a fallacy doesn’t mean it is wrong.

Next LSAT: January 26