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.


59 comments

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.


39 comments

Someone who gets sick from eating a meal will often develop a strong distaste for the one food in the meal that had the most distinctive flavor, whether or not that food caused the sickness. This phenomenon explains why children are especially likely to develop strong aversions to some foods.

Summarize Argument
The author concludes that children are especially likely to develop strong aversions to some foods. This is because people who get sick after eating a meal often develop an aversion to the strongest taste in the meal.

Notable Assumptions
In order for children to be especially likely to develop food aversions, the author assumes one of two things: that children are either especially likely to get sick after eating a meal, or that they’re especially likely to find certain tastes strong in a meal.

A
Children are more likely than adults to be given meals composed of foods lacking especially distinctive flavors.
This would weaken the author’s argument. Why would children be more likely to develop food aversions if their meals generally have less distinct flavors?
B
Children are less likely than adults to see a connection between their health and the foods they eat.
The author isn’t saying that people think the flavor will make them sick again. These aren’t voluntary aversions..
C
Children tend to have more acute taste and to become sick more often than adults do.
Children taste food stronger, and they become sick more often. Thus, the phenomenon the author describes applies more frequently to children than to adults. Hence why children are more likely to develop food aversions.
D
Children typically recover more slowly than adults do from sickness caused by food.
We don’t care how long recovery takes. We need to strengthen the connection between the hypothesis and the phenomenon.
E
Children are more likely than are adults to refuse to eat unfamiliar foods.
This is irrelevant. Any strong taste can factor into a food aversion.

31 comments

Besides laying eggs in her own nest, any female wood duck will lay an egg in the nest of another female wood duck if she sees the other duck leaving her nest. Under natural nesting conditions, this parasitic behavior is relatively rare because the ducks’ nests are well hidden. However, when people put up nesting boxes to help the ducks breed, they actually undercut the ducks’ reproductive efforts. These nesting boxes become so crowded with extra eggs that few, if any, of the eggs in those boxes hatch.

Summary
Any female wood duck will lay an egg in the nest of another female wood duck if she sees the other duck leave her nest. Under natural nesting conditions, this behavior is rare because wood duck nests are usually well hidden. However, nesting boxes put up by people undercut the wood duck’s reproductive efforts. Why? Because the nesting boxes become so crowded with eggs that few of them will ever hatch.

Strongly Supported Conclusions
If the nesting boxes put up by people were better hidden, then the boxes would be more successful in aiding the wood duck’s reproductive efforts.

A
Female wood ducks will establish nests in nest boxes only when natural nesting sites are not available.
We don’t know what causes a female wood duck to establish a nest in a nesting box. We only know that female wood ducks will lay eggs in another duck’s nest if she sees that duck leave the nest.
B
Nesting female wood ducks who often see other female wood ducks are the most successful in their breeding efforts.
We don’t know which female wood ducks reproduce most successfully.
C
The nesting boxes for wood ducks have less space for eggs than do natural nesting sites.
We don’t know whether the nesting boxes have less space. We only know that the nesting boxes tend to be overcrowded, but that does not imply that these nesting sights are smaller than natural nesting sites.
D
The nesting boxes would be more effective in helping wood ducks breed if they were less visible to other wood ducks than they currently are.
The argument concludes that the nesting boxes undercut the duck’s reproductive efforts because the boxes become overcrowded. If the cause for overcrowding the nests were reduced, then the effect of undermining reproductive efforts would also be reduced.
E
Nesting boxes are needed to supplement the natural nesting sites of wood ducks because of the destruction of much of the ducks’ habitat.
We don’t know whether the nesting boxes are needed, and we don’t know whether the wood ducks’ habitat is being destroyed.

82 comments