A
offers in support of its conclusion pieces of evidence that are mutually contradictory
B
overlooks the possibility that a person can practice law without being a member of a law firm
C
concludes that someone is not a member of a group on the grounds that that person does not have a characteristic that the group as a whole has
D
takes a high rate of success among the members of a group to indicate that the successes are evenly spread among the members
E
states a generalization based on a selection that is not representative of the group about which the generalization is supposed to hold true
The author also assumes that vehicles’ safety is accurately represented by those vehicles’ traffic fatality rates alone, and not, for example, injury rates.
A
It takes two smaller semitrailers to haul as much weight as a single triple-trailer can.
B
Highways in the sparsely populated West are much less heavily traveled and consequently are far safer than highways in the national system as a whole.
C
Opponents of the triple-trailers also once opposed the shorter twin-trailers, which are now common on the nation’s highways.
D
In areas where the triple-trailers are permitted, drivers need a special license to operate them.
E
For triple-trailers the rate of road accident fatalities per mile of travel was higher last year than in the two previous years.
A
it exploits an ambiguity in the term “environment” by treating two different meanings of the word as though they were equivalent
B
it fails to distinguish between actions that are socially acceptable and actions that are socially unacceptable
C
the way it distinguishes criminals from crimes implicitly denies that someone becomes a criminal solely in virtue of having committed a crime
D
its conclusion is a generalization of statistical evidence drawn from only a small minority of the population
E
its conclusion contradicts an implicit principle on which an earlier part of the argument is based
Yolanda: Gaining access to computers without authorization and manipulating the data and programs they contain is comparable to joyriding in stolen cars; both involve breaking into private property and treating it recklessly. Joyriding, however, is the more dangerous crime because it physically endangers people, whereas only intellectual property is harmed in the case of computer crimes.
Arjun: I disagree! For example, unauthorized use of medical records systems in hospitals could damage data systems on which human lives depend, and therefore computer crimes also cause physical harm to people.
Summarize Argument: Counter-Position
Arjun concludes that computer crimes also cause physical harm to people. He supports this with an example: unauthorized use of hospital medical records could damage data systems that are critical to human lives.
Identify and Describe Flaw
Arjun concludes that computer crimes do cause physical harm based on the example that unauthorized use of hospital medical records could damage data systems that are critical to human lives. In other words, in order to draw his conclusion, he must assume that something that could happen actually will happen.
A
fails to maintain a distinction made in Yolanda’s argument
Yolanda makes a distinction between joyriding and computer crimes. Arjun counters this distinction by claiming that computer crimes also cause physical harm. He doesn’t ignore her distinction.
B
denies Yolanda’s conclusion without providing evidence against it
Arjun denies Yolanda’s conclusion, but he does provide evidence: the example of unauthorized use of hospital medical records. The flaw lies in the relationship between this evidence and his conclusion.
C
relies on the actuality of a phenomenon that he has only shown to be possible
Arjun’s premise states that unauthorized use of hospital medical records could damage certain data systems, while his conclusion states that computer crimes do cause physical harm. So his conclusion depends on the actuality of something that he’s only shown to be a possibility.
D
mistakes something that leads to his conclusion for something that is necessary for his conclusion
This is the cookie-cutter flaw of mistaking sufficiency for necessity. Arjun doesn’t do this; he just gives an example to support his conclusion.
E
uses as evidence a phenomenon that is inconsistent with his own conclusion
This is the cookie-cutter flaw of internal contradiction. Arjun’s evidence may not support his conclusion well, but it is consistent with his conclusion.
Premiums for automobile accident insurance are often higher for red cars than for cars of other colors. To justify these higher charges, insurance companies claim that, overall, a greater percentage of red cars are involved in accidents than are cars of any other color. If this claim is true, then lives could undoubtedly be saved by banning red cars from the roads altogether.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that banning red cars could save lives, based on the claim that a greater percentage of red cars are involved in accidents than are cars of any other color.
Identify and Describe Flaw
This is a cookie-cutter “correlation does not imply causation” flaw, where the author sees a positive correlation and then assumes that one thing causes the other, without ruling out alternative hypotheses. She assumes that red cars cause car accidents simply because more red cars are involved in accidents. She goes on to conclude that banning red cars could save lives.
She overlooks the possibility that some other, underlying factor could be causing the correlation— maybe there’s something that causes people to buy red cars and to be involved in car accidents.
A
accepts without question that insurance companies have the right to charge higher premiums for higher-risk clients
Irrelevant— even if she does accept this, it has nothing to do with her argument. Her argument is about the correlation between red cars and accidents; insurance company rates are just context.
B
fails to consider whether red cars cost the same to repair as cars of other colors
Irrelevant— she may not consider repair costs, but this isn’t the flaw because repair costs don’t affect her argument. She hypothesizes that banning red cars could save lives; it doesn’t matter how much they cost to repair.
C
ignores the possibility that drivers who drive recklessly have a preference for red cars
This describes an alternative hypothesis that the author ignores. She assumes red cars cause accidents, without considering that some other, underlying factor may be causing the correlation— maybe reckless drivers just like red cars and that’s why more red cars are in accidents.
D
does not specify precisely what percentage of red cars are involved in accidents
Irrelevant— the exact percentage of red cars doesn’t matter, since we already know that “a greater percentage of red cars are involved in accidents” than cars of other colors.
E
makes an unsupported assumption that every automobile accident results in some loss of life
The author never makes this assumption. She just assumes that some car accidents result in some loss of life. Based on this assumption and the assumption that red cars cause accidents, she concludes that banning red cars could save lives.