PrepTest 158

This is unrelated to the question of GMOs' capacity to cause harm. If they have few advantages but do not cause harm, the scientist's argument is not any weaker.

This answer choice says that even if GMOs were harmful, those harms are mitigated by other factors. Mitigating factors would only strengthen the scientist's claims GMOs' risk is minimal, so this is incorrect.

This answer choice may be tempting, since it makes it seem like scientists don't really understand the food they're genetically engineering. But really, it is so weak that it doesn't have an effect on the argument. Scientists don't know what all 750,000 genes do in just some plants and animals? Even if that were true, they could still only alter the genes they understand, and the risks of altering those genes could be minimal.

Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Weaken

Stimulus Summary:
Some consumer groups feel GMOs could be harmful to humans. A scientist counters that argument by telling us that most intentional gene modification in plants consists of changing only one gene. Such a slight change, the scientist claims, could not have harmful effects. Therefore, the risk of GMOs is minimal.

Strategy Overview:

1. Argument or facts? Always argument, so identify premises and conclusions of argument
2. Anticipate why the premises are not enough to show that the conclusion is true
   1. Causal argument? Look for answer choice that:
      1. Shows possible alternate cause
      2. Shows cause without effect
      3. Shows effect without cause
      4. Shows the cause and effect are reversed
   2. If not causal argument, anticipate ways to worsen problem with argument
3. Use anticipations to select the answer choice that, if true, would weaken argument

Answer Anticipation:
This is technically a causal argument, albeit in the direction of arguing AGAINST a causal relationship. The consumer groups think GMOs could cause harm, but the argument concludes they probably don't.

To weaken the scientist's anti-causal argument, we could strengthen the consumer group's argument. So, reverse the usual causal anticipations for a weaken, and now we're looking for an answer choice that presents something that would strengthen this causal relationship:

• Same cause/same effect
• No cause/no effect
• Ruling out an alternate cause
• Ruling out that cause and effect are reversed

Of these, same cause/same effect seems like the most possible for the situation. But we've got to be careful here: we need to weaken the scientist's specific argument. The scientist pointed out that most GMOs involve altering a single gene and claimed that such a minor alteration could not cause harm.

So, an answer choice talking about harm caused by many simultaneously altered genes would not be correct. We need something specific to the situation the scientist brings up — a single altered plant gene.

Correct answer:

(D)

Answer Choice Explanation:
Yes! This answer choice presents the same cause (alteration of a single gene) and the same effect (changing the toxicity of the plant). So this answer choice strengthens the claim that altering a single gene might cause harm, which weakens the scientist's claim that changing a single gene is too insignificant to increase the risk of harm.

There are a few things that might give us pause about this answer choice. First, it's about plants we know to be toxic, while the passage focused on "foodstuffs," which are generally not toxic. Second, it discusses the toxicity to animals, not necessarily humans. Finally, it just says that the "toxicity is known to be affected" — it doesn't say that the toxicity is increased. However, these doubts should be erased when we remember how strong the scientists' assertion was. The scientist depends entirely on the claim that changing a single gene is just too minor a change to affect a plant's capacity to cause harm when eaten. This answer choice shows an instance when changing a single gene can affect a plant's ability to cause harm. Even if those plants are not ones we eat or genetically modify, even if the change would only affect nonhuman animals, and even if the change actually makes the plan less toxic, the answer choice still weakens the scientist's argument. It undercuts the scientist's claim that altering a single gene "cannot have effects significant enough" to increase the risk of harm. This answer choice shows it's possible alter a single gene and produce significant effects, so it is correct.

Key Takeaway:
Strengthen and Weaken questions are far from the "opposites" their names may imply. In fact, the strategies used for each overlap significantly. When an author claims that a cause-and-effect relationship doesn't exist on a Weaken question, we can look for an answer choice that strengthens that cause-and-effect relationship. Likewise, when an author claims that a cause-and-effect relationship doesn't exist on a Strengthen question, we can look for an answer choice that weakens that cause-and-effect relationship.

This is irrelevant. People can be ill-informed about a topic generally but correct about one specific fact (or even about the topic in general). Pointing out that someone is ill-informed may make one's argument less convincing, but it doesn't make their beliefs necessarily false. Even if did, this would only strengthen the scientists' argument.