Summarize Argument
The author concludes that a disease that would have had minor impacts on food supply in the past would be devastating today. This prediction is based on the observation that today’s crops lack diversity compared to crops in the past because farmers today only plant a few strains of a given crop.
Notable Assumptions
The author assumes that farmers today don’t have any way besides diversity to protect against diseases.
A
In the past, crop diseases would often devastate food supplies throughout entire regions.
The conclusion discusses specifically the diseases that would have had only minor impacts on the food supply in the past; the diseases referenced in (A) are outside of the scope of the argument.
B
Affected crops can quickly be replaced from seed banks that store many strains of those crops.
This weakens the argument. It gives a reason that a disease that would have had a minor impact on the food supply in the past would not be devastating today: today’s farmers have another way to protect against the disease other than crop diversity.
C
Some of the less popular seed strains that were used in the past were more resistant to many diseases than are the strains popular today.
This compares the less popular strains of the past with the popular modern strains; this comparison isn’t relevant. (C) also tells us that some old strains were more robust than the popular modern strains, which is consistent with the claim that today’s crops are more vulnerable.
D
Humans today have more variety in their diets than in the past, but still rely heavily on cereal crops like rice and wheat.
The argument is about the crops that make up the food supply, not specifically human diets as a whole, so this is not relevant to the argument.
E
Today’s crops are much less vulnerable to damage from insects or encroachment by weeds than were crops of a few generations ago.
The argument is specifically about the damage caused by diseases; it could be the case that today’s crops are safer from insects and weeds, but that diseases are still able to devastate today’s food supply.
Summarize Argument: Counter-Position
The local citizen claims that the measure to ban spectators from the courtroom was inconsistent with the stated reasoning for taking the measure. Since the court stirred up public interest with requests for help, the citizen claims that it’s hypocritical for public interest to be invoked as the reason for restricting courtroom attendance.
Identify and Describe Flaw
This is an “equivocation fallacy”, meaning that the local citizen uses different meanings of a word interchangeably in an invalid way. In the argument’s premises, the term “public interest” refers to the fact that the public cared about the case. Later, however, the term refers to what would be good for the public. There’s no contradiction because those two concepts are very different.
A
generalizes from an atypical case
The citizen never generalized. The argument was only concerned with this one particular turn of events.
B
trades on an ambiguity with respect to the term “public interest”
This describes the way the term “public interest” was treated as though it referred to the same concept even though the term’s meaning shifted throughout the argument.
C
overlooks the fact that the judge might not be the one who made the plea to the public for help
The central flaw with the argument was the inconsistent use of a term. No matter who specifically made the plea for help, the supposed contraction could still stand.
D
attempts to support its conclusion by making sensationalistic appeals
The citizen refers to events that actually happened, so the premises weren’t merely sensationalistic appeals. Employing rhetoric isn’t a logical flaw in and of itself.
E
presumes that the public’s right to know is obviously more important than the defendant’s right to a fair trial
This is irrelevant. Actions could still be inconsistent regardless of what the defendant’s rights are. Also, there’s no reason to believe that allowing spectators would infringe on the defendant's rights.
Summary
If one effect of a genetic mutation contributes substantially to survival of a species, that mutation will be favored in natural selection. In addition, if a mutation is favored in natural selection, that means at least one effect of that mutation contributes substantially to survival of a species.
The rules above are subject to one exception — when the effect of traits that are carried along with the genetic mutation are so negative that they cancel out the benefits of a mutation, the mutation won’t be favored.
The rules above are subject to one exception — when the effect of traits that are carried along with the genetic mutation are so negative that they cancel out the benefits of a mutation, the mutation won’t be favored.
Notable Valid Inferences
There’s no clear inference to draw. We just need to understand the complicated rules in the stimulus accurately.
A
A species possesses a trait whose effects are all neutral for the survival of that species.
Could be true. A species can have a trait with only neutral effects. This just implies the trait won’t be favored by natural selection.
B
All the effects of some genetic mutations contribute substantially to the survival of a species.
Could be true. There could be some mutations that only do very helpful things for survival. These mutations will be favored.
C
A species possesses a trait that reduces the species’ survival potential.
Could be true. A species can have a trait that reduces survival potential. This trait won’t be favored.
D
A genetic mutation that carries along several negative traits is favored in natural selection.
Could be true. A genetic mutation can carry several negative traits. And that mutation can still be favored as long as the negative traits aren’t so negative as to outweigh the benefits of the mutation.
E
A genetic mutation whose effects are all neutral to a species is favored in natural selection.
Must be false. If the effects are all neutral, then the mutation won’t be favored. One requirement to be favored is that one effect contributes substantially to survival.
Kendrick: Governments that try to prevent cigarettes from being advertised are justified in doing so, since such advertisements encourage people to engage in an unhealthy practice. But cigarette advertisements should remain legal since advertisements for fatty foods are legal, even though those advertisements also encourage people to engage in unhealthy practices.
"Surprising" Phenomenon
How can governments that try to prevent cigarettes from being advertised be justified in these attempts, even though cigarette advertisements should remain legal?
Objective
The correct answer should show how governments might be justified in trying to stop cigarette advertisements even if these advertisements should still be legal. Perhaps there’s a method to prevent cigarette advertisements that doesn’t involve trying to ban them or make them illegal.
A
Any advertisement that encourages people to engage in an unhealthy practice should be made illegal, even though the legality of some such advertisements is currently uncontroversial.
One part of the discrepancy is the fact that the advertisements should be legal. (A) contradicts this fact by saying these advertisements shouldn’t be legal. Denying one of the facts doesn’t help resolve the discrepancy.
B
The advertisement of fattening foods, unlike that of cigarettes, should not be prevented, because fattening foods, unlike cigarettes, are not addictive.
What the government should do with fattening foods doesn’t impact what the government should do with cigarettes.
C
Most advertisements should be legal, although advertisers are always morally responsible for ensuring that their advertisements do not encourage people to engage in unhealthy practices.
But how can the government still be justified in attempting to prevent cigarette advertisements from being shown? This answer doesn’t provide a potential answer.
D
Governments should try to prevent the advertisement of cigarettes by means of financial disincentives rather than by legal prohibition.
Even though cigarette advertisements should be legal, the government can be justified in preventing cigarette advertisements through financial disincentives. For example, maybe taxing the ads could get cigarette companies to refrain from showing ads.
E
Governments should place restrictions on cigarette advertisements so as to keep them from encouraging people to engage in unhealthy practices, but should not try to prevent such advertisements.
Part of the discrepancy is that the government is justified in trying to prevent cigarette advertisements. (E) contradicts this part of the discrepancy by saying the government should not try to prevent the ads. Contradicting one part of the discrepancy doesn’t help explain it.
Summary
Failure to rotate crops depletes the soil’s nutrients gradually unless other preventative measures are taken. If the soil’s nutrients are completely depleted, then additional crops can be grown only if fertilizer is applied to the soil. If vegetables are grown in soil that has had fertilizer rather than being grown in non-fertilized soil, they are more vulnerable to pests. Consequently, these vegetables must be treated with larger amounts of pesticides. The more pesticides used on vegetables, the greater the health risks to humans from eating those vegetables.
Notable Valid Inferences
The vegetables were grown in soil not completely depleted of nutrients.
A
The soil in which the vegetables were grown may have been completely depleted of nutrients because of an earlier failure to rotate crops.
Must be false. As shown in our diagram, soil that is completely depleted and growing crops requires the use of fertilizer.
B
It is not possible that the vegetables were grown in soil in which crops had been rotated.
Could be false. We have no information in the question stem that would trigger the first set of conditionals in our diagram. We are only given the condition that fertilizer has never been used, which triggers our second set of conditionals.
C
The vegetables were grown in soil that had not been completely depleted of nutrients but not necessarily soil in which crops had been rotated.
Must be true. As shown below, if fertilizer has never been used it is impossible that the soil is completely depleted of nutrients. 
D
Whatever the health risks to humans from eating the vegetables, these risks would not be attributable to the use of pesticides on them.
Could be false. We only know that the vegetables were grown in soil that has never had fertilizer applied. We do not know whether pesticides were also used.
E
The health risks to humans from eating the vegetables were no less than the health risks to humans from eating the same kinds of vegetables treated with pesticides.
Could be false. We only know that the more pesticides used on crops, the greater the health risks to humans. We do not know whether pesticides were used on the vegetables, we only know that they were grown in soil that has never had fertilizer.