PrepTest 76, Section 2, Question 1
In the bodies of reptiles, some industrial by-products cause elevated hormonal activity. Hormones govern the development of certain body parts, and in reptiles abnormal development of these parts occurs only with elevated hormonal activity. Recently, several alligators with the telltale developmental abnormalities were discovered in a swamp. So, apparently, industrial by-products have entered the swamp's ecosystem.
In the bodies of reptiles, some industrial by-products cause elevated hormonal activity. Hormones govern the development of certain body parts, and in reptiles abnormal development of these parts occurs only with elevated hormonal activity. Recently, several alligators with the telltale developmental abnormalities were discovered in a swamp. So, apparently, industrial by-products have entered the swamp's ecosystem.
In the bodies of reptiles, some industrial by-products cause elevated hormonal activity. Hormones govern the development of certain body parts, and in reptiles abnormal development of these parts occurs only with elevated hormonal activity. Recently, several alligators with the telltale developmental abnormalities were discovered in a swamp. So, apparently, industrial by-products have entered the swamp's ecosystem.
In the bodies of reptiles, some industrial by-products cause elevated hormonal activity. Hormones govern the development of certain body parts, and in reptiles abnormal development of these parts occurs only with elevated hormonal activity. Recently, several alligators with the telltale developmental abnormalities were discovered in a swamp. So, apparently, industrial by-products have entered the swamp's ecosystem.
The reasoning in the argument is most vulnerable to criticism on the grounds that the argument
provides no explanation for developmental abnormalities that do not result from elevated hormonal activity
fails to consider whether elevated hormonal activity can result from factors other than the presence of industrial by-products
fails to address the possibility that industrial by-products were contained in food the alligators ate
fails to say whether reptiles other than alligators were examined for the same developmental abnormalities that were discovered in the alligators
uses evidence drawn from a sample of alligators that is unlikely to be representative of alligators in general
Explanations
The argument concludes that industrial by-products have entered a particular swamp's ecosystem. Let's pick apart their evidence.
First, they say some industrial by-products cause elevated hormonal activity.
Next, they tell us hormones govern the growth of certain body parts.
They continue by noting that, in reptiles, elevated hormonal activity is necessary for the abnormal development of certain body parts.
Then, we're told that several alligators (i.e., reptiles), are showing the telltale signs of such abnormalities.
See the mistake now? This is a classic case of confusing sufficient and necessary. The author's conclusion assumes that industrial by-products hitting the swamp is the only way these gators could have ended up with elevated hormonal activity. It's possible it could be many other things leading to those circumstances.
Turns out it's a flaw question, so the correct answer should stick out like a sore thumb.
Let's take a look.
No, this isn't it. These abnormalities were "telltale," meaning they track closely with what we might expect from industrial by-product contamination, but that still doesn't mean it's definitely from such contamination.
Bingo. This is a more literal phrasing of it, but this is what the author did, and did wrong. Their conclusion would require them to believe that the only way these gators got their extra toes was from industrial by-product contamination, and nothing else.
No, the author doesn't overlook this possibility. This could totally be a possibility the author considers. It's still not our flaw.
Nope. The author does fail to say this, but it's ultimately irrelevant to the argument being made.
Nah. We have no evidence about the sample size of the alligators. Moreover, it wouldn't necessarily matter if we did. The argument is concerned with the causal relationship between industrial by-products, hormonal elevation, and abnormalities in reptiles—namely alligators in this swamp—, which isn't proven by the facts provided.
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