Summarize Argument: Phenomenon-Hypothesis
The microbiologist hypothesizes that the bacteria’s exposure to heavy metals in sewage sludge caused them to develop antibiotic resistance. He supports this by saying that since heavy metals are concentrated in the sludge, bacteria that survive there have evolved to resist heavy-metal poisoning, and these same bacteria are resistant to antibiotics.
Notable Assumptions
The microbiologist assumes that heavy metal exposure can promote antibiotic resistance in certain bacteria. He also assumes that there are no alternative hypotheses to explain the observed correlation— that is, he assumes that there is not a third factor that causes both antibiotic resistance and heavy-metal poisoning resistance. He also assumes that the causal relationship is not reversed— that is, that antibiotic resistance does not cause heavy-metal poisoning resistance.
A
Most bacteria that are not resistant to antibiotics are not resistant to heavy-metal poisoning either.
The microbiologist is only addressing those bacteria that are resistant to both heavy-metal poisoning and antibiotics. Even if (A) is true, it wouldn’t impact his conclusion that heavy-metal exposure causes antibiotic resistance in certain bacteria.
B
Bacteria that live in sewage sludge that is free of heavy metals, but is in other respects similar to normal sewage, are generally resistant to neither heavy-metal poisoning nor antibiotics.
This strengthens the hypothesis by providing a control group. If bacteria in sludge without heavy metals aren’t resistant to heavy-metal poisoning or antibiotics, it’s more likely that the heavy-metal exposure did cause antibiotic resistance in the bacteria in the other sludge.
C
Antibiotic resistance of bacteria that survive in sewage sludge in which heavy metals are concentrated contributes to their resistance to heavy-metal poisoning.
This weakens the microbiologist’s hypothesis by suggesting that the causal relationship is reversed. That is, (C) suggests that antibiotic resistance causes heavy-metal poisoning resistance, rather than the other way around.
D
Sewage sludge that contains high concentrations of heavy metals almost always contains significant concentrations of antibiotics.
This weakens the hypothesis by providing a plausible alternative explanation. If sludge that contains heavy metals also contains significant amounts of antibiotics, it’s likely that the antibiotics cause antibiotic resistance in the bacteria, not the heavy-metal exposure.
E
Many kinds of bacteria that do not live in sewage sludge are resistant to both heavy-metal poisoning and antibiotics.
This doesn’t strengthen the hypothesis that heavy-metal exposure caused antibiotic resistance in the bacteria. We don’t know if the bacteria described in (E) were exposed to heavy metals or not.
Summary
Marital vows often contain a certain promise that uses the word “love.” The author concludes that “love” in this context should not be interpreted as referring to feelings. This is because the promise would make no sense if “love” referred to feelings.
Missing Connection
The conclusion asserts that we should not interpret the word “love” as referring to feelings in the context of a certain promise. But the premises do not establish when one should not interpret a word in a particular way. The premises only establish that interpreting “love” as referring to feelings makes no sense. So to get from the premise to the conclusion, what’s missing is the principle that if an interretation makes no sense, one should not use that interpretation.
A
None of our feelings are within our control.
(A) doesn’t tell us when we should not interpret a word in a particular way. So it cannot establish that we should not interpret “love” as referring to feelings in the context of the promise.
B
People should not make promises to do something that is not within their control.
(B) concerns whether a promise should be made. But the argument concerns whether a certain word in a promise should be interpreted in a particular way. How a word should be interpreted has nothing to do with whether a promise should be made.
C
“Love” can legitimately be taken to refer to something other than feelings.
(C) establishes that “love” can refer to other things besides feelings. But it doesn’t guarantee that we SHOULD NOT interpret “love” as referring to something else besides feelings in the context of the promise.
D
Promises should not be interpreted in such a way that they make no sense.
We know from the premises that interpreting “love” as referring to feelings in the context of the promise makes no sense. (D) establishes that if an interpretation of a promise makes no sense, then we should not use that interpretation. So (D), combined with the premises, proves we should not interpret “love” as referring to feelings in the context of the promise.
E
Promises that cannot be kept do not make any sense.
(E) doesn’t tell us when we should not interpret a word in a particular way. So it cannot establish that we should not interpret “love” as referring to feelings in the context of the promise.
Application: Crackly Crisps need not be labeled as containing genetically engineered ingredients, since most consumers of Crackly Crisps would not care if they discovered that fact.
Summarize Argument
The argument concludes that Crackly Crisps do not need to be labeled as containing genetically engineered ingredients. This is based on a principle: food products should be labeled as containing ingredients that would upset most consumers of that product. We also know that genetically engineered ingredients would upset most consumers of Crackly Crisps.
Identify and Describe Flaw
The argument is flawed because it confuses necessary and sufficient conditions. According to the principle, an ingredient upsetting consumers of a product is a sufficient condition to label the product as containing that ingredient. However, the application treats upsetting consumers as a necessary condition.
The genetically engineered ingredients in Crackly Crisps may not upset the consumers, but that doesn’t guarantee that they need not be labeled.
The genetically engineered ingredients in Crackly Crisps may not upset the consumers, but that doesn’t guarantee that they need not be labeled.
A
fails to address the possibility that consumers of a specific food may not be representative of consumers of food in general
Only the consumers of a specific food product are relevant for the principle given in the argument. The argument just doesn’t make any claims about consumers of food in general, only the consumers of Crackly Crisps.
B
fails to address the possibility that the genetically engineered ingredients in Crackly Crisps may have been proven safe for human consumption
It’s irrelevant to the argument whether a product’s ingredients are safe for human consumption, only whether most consumers of the product would be upset to learn that those ingredients are included in the product.
C
implicitly makes use of a value judgment that is incompatible with the principle being applied
The argument doesn’t make any value judgments about genetically engineered ingredients, product labeling, or anything else relevant.
D
takes for granted that if most consumers of a product would buy it even if they knew several of the ingredients in it, then they would buy the product even if they knew all the ingredients in it
The argument doesn’t make this claim. It also never implies that this is the case.
E
confuses a claim that under certain conditions a certain action should be taken with a claim that the action need not be taken in the absence of those conditions
The argument treats a sufficient condition—an ingredient upsetting most consumers of a product—as if it were a necessary condition for labeling a product as containing that ingredient. The absence of a sufficient condition doesn’t guarantee that the product need not be labeled.
Summarize Argument
The editorialist concludes that the voluntary garbage-sorting system should be retained. This is because the alternative, a mandatory garbage-sorting system, would foster resentment. In turn, many people would refuse to sort their garbage at all.
Identify Argument Part
The referenced text is a concession the editorialist makes about an alternative to the practice she recommends. It’s true that the town would spend less under a mandatory sorting system, but the editorialist suggests there are other things to consider.
A
It is a claim that the editorial is trying to show is false.
The editorialist concedes that the town wouldn’t have to spend as much under a mandatory system. He simply believes there are reasons to retain the current system.
B
It is a fact granted by the editorial that lends some support to an alternative to the practice that the editorial defends as preferable.
The editorialist agrees that the town wouldn’t have to spend as much under a mandatory system, which certainly supports installing such a system. Still, the editorialist defends the current system as a better option.
C
It is an example of a difficulty facing the claim that the editorial is attempting to refute.
The editorialist isn’t refuting a claim. Instead, he’s recommending one of two options.
D
It is a premise that the editorial’s argument relies on in reaching its conclusion.
The fact that a mandatory system would be less expensive doesn’t support the editorialist’s argument. It’s a fact he concedes about one option while arguing for the other.
E
It is the conclusion that the editorial’s argument purports to establish.
The editorialist doesn’t try to support the claim that a mandatory system would cost less. He argues instead for retaining a voluntary system.
Summary
Hot spots are places with the highest concentrations of endemic species. Habitats at many hot spots are threatened by commercial development. This threatens the endemic species in these hot spots. Most extinctions involve loss of endemic species.
Strongly Supported Conclusions
We’re looking to fill in a blank concerning what would be reasonable to do for organizations dedicated to preserving species, given that these organization can’t fight for every environmental cause. The evidence suggests it’s reasonable for these organizations to try to protect hot spots from commercial development.
A
try to help only those species who are threatened with extinction because of habitat loss
Unsupported. The stimulus gives us evidence about hot spots and the threats to species in hot spots. This conclusion isn’t focused on hot spots. Species threatened because of habitat loss includes more than just species threatened in a hot spot. So this conclusion is too broad.
B
concentrate their resources on protecting hot spot habitats
Strongly supported. The evidence concerned endemic species in hot spots, and a significant proportion of extinctions involve endemic species. So there’s strong reason to focus on protecting hot spots, which are defined as the places with the most endemic species.
C
treat all endemic species as equally valuable and equally in need of preservation
Unsupported. The stimulus may support that idea that endemic species are more in need of protection than non-endemic species. But we don’t have enough to draw conclusions about individual endemic species compared to other endemic species. Some may be more important than others.
D
accept that most endemic species will become extinct
Unsupported. The stimulus doesn’t support giving up. It supports directing efforts to hot spots. We don’t have any basis to say these effort are likely to fail or that organizations should just accept species loss. Maybe there efforts can succeed and save most endemic species.
E
expand the definition of “hot spot” to include vulnerable habitats that are not currently home to many endangered species
Unsupported. The stimulus supports a conclusion about where organizations should focus their efforts concerning species protection. Expanding the definition of hot spot wouldn’t help protect more species, because we don’t know if anyone is trying to protect hot spots yet.
Application: Wilton sold a used bicycle to Harris, knowing very little about its condition. Wilton told Harris that the bicycle was in good working condition, but Harris soon learned that the brakes were defective. Wilton was therefore guilty of fraud.
Summarize Argument
The author concludes that Wilton was guilty of fraud. This is based on the following:
If one sells an item that they know is defective, but tells the buyer that the item is not defective, that constitutes fraud.
Wilton sold a bicycle to Harris, without knowing whether it was defective.
Wilton told Harris the bicycle was not defective, but it turned out to be defective.
Identify and Describe Flaw
The author assumes that Wilton knew the bicycle was defective. But all we know is that Wilton didn’t know about the bicycle’s condition. He might not have known that it was defetive.
A
the application fails to establish whether Wilton was given the opportunity to repair the brakes
Whether one has the opportunity to fix an item has nothing to do with the principle.
B
the application fails to indicate how much money Wilton received for the bicycle
The amount of money received for an item has nothing to do with the principle.
C
the application uses the word “defective” in a sense that is crucially different from how it is used in the statement of the principle
The word “defective” is not used in two different ways.
D
Harris might not have believed Wilton’s statement about the bicycle’s condition
Whether the buyer believes what the seller says has nothing to do with the principle.
E
asserting something without justification is not the same as asserting something one knows to be false
Wilton asserted that the bicycle was not defective, even though he didn’t have justification for that claim. But this is not the same as saying that an item is not defective while knowing that it is. Wilton did not know it was defective.