V33-06

Official Solution:


In the nature-versus-nurture debate, when it comes to general intelligence, as measured by IQ scores, nurture wins out. Otherwise, there would be no need for expectant mothers to take prenatal vitamins with added folate to aid with brain development in the growing fetus, and early-learning advancement products such as the Baby Genius series of musical toys would find no market, not to mention that parents would have no need to read to their children or encourage their children to read to develop language skills ahead of their peers.

Which of the following, if true, casts the most doubt on the argument presented in the passage?


A. Some of the most profound thinkers in history with the highest IQs have begun to speak at a later age than most of their peers.
B. Since a link between folate and brain development was established several decades ago, general human intelligence, as measured by IQ scores, has not risen by any significant amount.
C. The Baby Genius series of products has been heavily criticized by a number of leading researchers in cognitive development research.
D. In cases in which identical twins have been adopted at birth by different families, the twins have always had IQ scores that fell within 5 points of each other, when one standard deviation on the IQ scale is 15 points.
E. Studies show that a developing fetus can recognize its parents’ voices and the intonations of their spoken language even if those parents never read to the child once it is born.


This is a straight-up weaken the argument question:





In any strengthen/weaken question, be sure to stick to the exact argument put forth. Associative thoughts will often lead you down an incorrect path, and answer choices are carefully designed to play into such reasoning.





First off, on a side note, I know the GMAT™ would not touch a topic as controversial as IQ scores with a ten-foot pole. But this is just for fun, just for us, an exercise for us to practice CR-style passages and questions to better prepare for the real thing. Sentence one is the argument. A claim is put forth that, based on IQ score information regarding general intelligence, nurture wins out [in the nature-versus-nurture debate. Sometimes this happens in passages. The argument or conclusion comes first, with premises, the why behind the what, to follow.

Sentence two is lengthy, but it merely lists reasons to support the argument of the previous sentence, relying on negation to make the point: 1) mothers-to-be take prenatal vitamins; 2) there is a market for early-learning advancement products; 3) parents read to their children; and 4) parents encourage their children to read.

There are plenty of holes to spot here, but remember, do not lose sight of the argument itself, just as it is presented in the first sentence. We need to find a flaw with the argument, not with any of the premises.





A nod to Einstein, anyone? I caution people about vague, non-committal language such as some in many of my CR posts. It is a common trap that plays on associative reasoning. (There are exceptions in which you want a some answer, but most of the time, you should tread carefully.) Here, if some profound thinkers have been late talkers, what about other profound thinkers? Some could refer to just two, and those two might be exceptions to a general trend. Most importantly, ask yourself whether this information compellingly works against the notion that nurture wins out, regarding intelligence. To be honest, you should not be able, with this information, to make any headway on either side of the debate. I call this a red light answer.





The problem here is that just because such a link was found, we cannot say that expectant mothers have been taking prenatal vitamins with added folate. The passage does not provide any information to that effect. (Be careful not to read between the lines.) The argument could still hold that nurture would be more important than nature, particularly if the mothers who took prenatal vitamins ended up producing children with higher intelligence, on average, than that of the general population. Red light.





This appeal to authority has no bearing on the argument. It latches onto a premise about early-learning advancement products and creates an issue out of nothing more than a detail. If leading researchers go against a product for a particular reason, then that product might be substandard for that reason, but we could not then extrapolate anything about the larger concern at hand. Red light.





Notice the absolute language in always. This type of language is either overreaching or used to almost over-qualify an answer choice. (Significantly works in a similar capacity and often appears in correct answers, as though GMAC™ wants to make the correct answer less debatable.) The idea here is that no matter what, identical twins end up roughly the same in terms of intelligence, using the very metric that the argument, flawed or not, is based upon. Sure, we have no idea how these twins may have been raised, but the very fact that they have been separated and raised in whichever way, yet still come out with roughly the same intelligence, makes a strong case for a natural (non-nurtured) or innate intelligence. This is just what we are looking for to weaken the argument that nurture wins out. Green light.





Studies is another iteration of some. How many studies? Three? Five? And what does this natural linguistic capability have to do with the argument presented, one that leans on IQ scores to make a point? Because the answer is long-winded, it may be harder to follow. If that proves to be the case for you with any answer choice, then just yellow light that option in the first pass and move on. Work from a place of comfort and get rid of what you either know is incorrect or have a very strong feeling about to that end. You can reassess if you need to on a second pass. In this case, though, once we break it down, we should realize that it does not affect the argument at all, so it cannot be the answer to the question being asked. Red light.

I hope that helps. Again, do not be afraid to look back at the passage and reread that argument or conclusion as often as is necessary to make heads or tails of a given answer choice. Lose track of that exact argument, and CR will never prove to be anything more than a guessing game.


Answer: D