#25 - Advertisement: The dental profession knows that

[Administrator]

Complete Question Explanation

Parallel Reasoning—Flaw. The correct answer choice is (D)

The advertisement in this stimulus describes a survey of five dentists. Each agreed that the tartar control formula found in Blizzard is the most effective cavity fighting formula available in a toothpaste. From this evidence, the advertisement concludes that the dental profession knows that brushing with Blizzard toothpaste is the best way to fight cavities.

This argument has more than one flaw. The conclusion is expansive, expressing the knowledge of the dental profession as a whole concerning the best way to fight cavities. Yet the only support for this conclusion is a survey of only five dentists whose opinion concerned only the most effective cavity fighting formula available in a toothpaste. So, the argument commits a survey error, by basing its very broad conclusion on a very small sample. It also commits an error in the use of evidence, by exaggerating the actual response given by the dentists.

This is a Parallel Reasoning—Flaw question. Your prephrase is that the correct answer choice will contain both the survey error and the error in the use of evidence.

Answer choice (A): Although the conclusion in this choice infers the opinion of the “nation’s voters” from a survey of only ten voters, the statement concerning their opinion does not match the flaw in the stimulus. While the conclusion in the stimulus concerning the “best way to fight cavities” was exaggerated, it at least was tied closely to the opinion offered by the five dentists. Here, the conclusion that Gomez’s policies would be best for the nation is not properly related to the opinion expressed by the ten voters that Gomez would be a very popular leader.

Answer choice (B): This choice is incorrect because it does not commit the survey error. Here, the argument concludes that “some of the nation’s voters believe.” Since “some” means at least one, but possibly all, the reference to “some” in the conclusion is appropriate.

Answer choice (C): The argument in this choice is distinct from the stimulus in that the number of people surveyed is more appropriate to the breadth of the conclusion. As opposed to “five dentists” in the stimulus, here “thousands of voters” were polled.

Answer choice (D): This is the correct answer choice. This choice has both the flaws identified in the stimulus. First, it draws a conclusion regarding the knowledge of the electorate from a survey of only ten voters. Next, the argument concludes from a statement regarding Gomez’s policies that electing Gomez would be the “best” way to help the nation.

Answer choice (E): The argument in this choice does not ascribe knowledge to a group whose size is not supported by evidence. Here, the argument concludes that “we know” something based on the responses of ten voters “we surveyed.”

[moshei24]

The flaw in this question is that the sample is too small to be representative of the whole?

Thanks!

[Steve Stein]

Hi Moshe,

That's right, one flaw is that the samples seem quite small. Another is that the author draws a conclusion that is too broad. And another is that knowledge is ascribed to a pretty big group (the dental profession) without any basis. Here's how the stimulus does it:

Premise: Blizzard is the most effective way to fight cavities with a toothpaste.
Conclusion:The Dental profession knows that Brushing with Blizzard is the best way to fight cavities.

Similarly, the correct answer choice uses a small sample and draws an overly broad conclusion:

Premise: The policies Gomez likes are the most helpful policies.
Conclusion: The nation's voters know that electing Gomez is the best way to help the nation.

I hope that's helpful--let me know--thanks!

~Steve

[moshei24]

Right, isn't that what I'm saying?

It takes what a few people said to be representative of the whole.

Five dentists to speak for the whole dental profession and ten voters to speak for the entire nation. Isn't that what the issue is?

[Steve Stein]

Hi Moshe,

Yes, that's one of the issues. Beyond the issue of representativeness, though, can you see how the author leaps from a premise about the best toothpaste to an overly broad conclusion about the best way to fight cavities?

The author of the correct answer choice makes the same unjustified leap from a premise about the best policies to a conclusion about electing Gomez' being the best way to help the nation.

Please let me know whether that's clear--thanks!

~Steve

[moshei24]

I see, I see. Thanks! That stimulus has lots of issues, lol.

[ylikate]

My thoughts were that there are 2 flaws in this question (1) too small sample - from "5 dentists" to "dental profession" and (2) subj change "most effective formula to "best toothpaste"
(A) seems to commits both flaws. Can someone help me understand why A is incorrect and D is superior? Thanks.

[KelseyWoods]

Hi ylikate,

Thanks for your question! You're very close in the way you prephrased those flaws. One flaw is definitely the small sample size which both A and D exhibit--moving from "ten voters" to "the nation's voters" just like the stimulus moves from "five dentists" to "the dental profession."

But the second flaw is not quite the shift from "most effective formula" to "best toothpaste." The real shift present is from "most effective cavity-fighting formula in a toothpaste" to "best way to fight cavities." Having the most effective cavity-fighting formula probably would make it the best toothpaste for fighting cavities. But being the best cavity toothpaste wouldn't necessarily make it the best WAY to fight cavities. The best way to fight cavities might be to refrain from eating sugar, or to get dental sealants, or to have all your teeth pulled and just go with dentures--none of which have anything to do with toothpaste. So what we really need in the correct answer is an argument that says just because something is the best in its category, that means it is the best of all the categories.

A is missing this flaw. A shifts from "popular" to having the "best policies," which is certainly a flaw, but it isn't quite the same as saying that something is the best in its category so therefore it's the best overall.

D exhibits this flaw more apparently. D says that Gomez essentially has the "best policies for helping the nation" so therefore Gomez is the "best WAY to help the nation." Again, just because he has the best policies, doesn't actually mean that his policies are the best way to help the nation. Maybe the best way to help the nation would be to completely overthrow the government.

Does that help?

Kelsey

[ylikate]

Thanks Kelsey. I appreciate the detailed explanation.

[Leela]

While I had correctly prephrased the flaws in the stimulus, my instinct was that I also needed to match absolutes in the conclusion ("best way to fight cavities") and premises ("most effective cavity-fighting formula"). I chose B, because it used "best for the nation" and " best policies for the nation to adopt." In parallel flaw questions, do you only have to parallel the method of reasoning, ignoring the conclusion, premises, and validity?