LSAT 91 - Section 2 - Question 24

This is a Weaken question.

The argument starts with a report of what some people believe. They believe that the economic benefits of genetically engineered foods may be offset by the hidden health risks. That's the context, that's other people's position. The author, who is a scientist, signals the transition to argument with the word “however.” She hits us with her conclusion that the risk, referring to the risk to human health, is minimal. Why should we believe this conclusion? The rest of the stimulus provides reasons.

The first premise is that in most cases of deliberate alteration of a plant's genetic structure, only a single gene out of 750,000 is changed. She then says that since the change is so slight, it cannot have effects significant enough to be worrisome.

There are many assumptions in this argument but perhaps the most crucial assumption is whether a single gene change can cause effects significant enough to be worrisome. If it's true that the alteration of a single gene cannot have effects significant enough to be worrisome, then her conclusion follows pretty strongly. It does seem like the risk, from plant foods anyway, is minimal. However, if it's not true, if even a single genetic alteration is capable of producing significant effects to be worrisome, then her argument is severely weakened.

This is what Correct Answer Choice (D) reveals. It says that there are plants that are known to be toxic to some animals and whose toxicity is known to be affected by the alteration of a single gene. (D) reveals that indeed it is possible for the alteration of a single gene to have effects significant enough to be worrisome. This suggests that the crucial assumption in the argument is false. Note that this answer does not overshoot the requirement of Weaken questions. If you object to this answer on the grounds that we don't know if these plants in (D) are analogously similar to the plants that we're talking about in the stimulus, then you are trying to do too much. You're trying to prove the opposite of the conclusion. In other words, you're trying to prove that there is a significant risk to human health from the alteration of a single gene in, say, the corn that we grow. Indeed, to do that, we do need to show that the alteration of a single gene in corn results in toxicity. But that's not what we're trying to do. We're just trying to weaken the argument. (D) easily crosses that threshold.

Granted we didn't talk about the other assumptions that the argument made. Another big one is that the premises only talk about altering a plant's genetic code. The conclusion is more broadly stating that the risk of foodstuffs in general is minimal. That includes meat and other animal products as well.

Answer Choice (A) says the genetically engineered plants that have been developed so far have few advantages over plants that are not genetically engineered. If the argument above worked on a cost-benefit logic, then (A) might be relevant. Even so, (A) only explicitly confirms that there are advantages, just not that many of them. But the affirmation of the advantages that do exist, few as they are, has no bearing on any of the assumptions made in the actual argument.

Answer Choice (B) says whatever health risks there are in foods from genetically altered plants may be somewhat reduced by other factors. And then it goes on to state what those factors are. This being true does not weaken the argument. Notice that (B) doesn't take a position on whether health risks exist. It just says that if those health risks exist, they may be reduced. So in the world in which health risks exist, (B) provides ways to mitigate that risk. But that's not what we're talking about. We're trying to figure out if we are in a world where the risk is significant or if we are in a world where the risk is minimal.

Answer Choice (C) says scientists have yet to determine for each characteristic of some plants and animals used for food the precise location of the genes that determine a characteristic. If we are able to parse this statement, I think we'll see that it has no bearing on the argument. What the statement is saying is that we don't have a complete mapping of the observable characteristics (phenotype) of plants and animals onto the genes that are responsible for those characteristics. So, for example, we might observe that a particular variety of corn happens to be highly resistant to heat, or that it may be very fragrant, or that it grows really well regardless of the time of year. Those are all observable characteristics (phenotypes) that are controlled by genes. (C) is saying that we just don't know which genes control those characteristics. That's totally fine. The argument doesn't require a complete mapping of genes to observable characteristics. It just requires the assumption that a small change in a single gene can't have significant negative effects that we should worry about.

Answer Choice (E) says the research has shown that those consumers who are most strongly opposed to genetically altered foods tend to be the most ill-informed on the issue. Again this has no bearing on the argument. The argument is about whether a single genetic alteration can produce effects that warrant concern. How consumers feel about this is utterly irrelevant. (E) tells us that the consumers who are most strongly opposed are most ill-informed and the consumers that are least opposed are best-informed. That makes sense but it has nothing to do with the argument.