#22 - The return of organic wastes to the soil is a good

[Administrator]

Complete Question Explanation

Parallel Flaw—SN. The correct answer choice is (C)

Here, the stimulus begins with a conditional rule, that if returning organic wastes to the soil is a good solution to waste disposal problems, then it must be the case that the wastes are non-toxic and not too much energy is expended in transporting them. We can diagram this rule as:

good solution = return of organic wastes is a good solution to waste disposal problems
toxic = the wastes are toxic
too much energy = too much energy is expended in transporting the wastes

• Sufficient Necessary
  
  toxic
  
  good idea +
  
  too much energy

Next, the author tells us that in the case of small-scale organic farming, the wastes are nontoxic (toxic) and that it is not the case that too much energy is expended in transporting the wastes (too much energy). In other words, the author tells us that in the case of small-scale organic farming, both of the rule’s necessary conditions are satisfied. Based on this evidence, the author concludes that, in the case of small-scale organic farming, returning the organic wastes to the soil is a good solution to waste disposal problems (good solution).

This conclusion is flawed because it is the Mistaken Reversal of the rule provided in the first sentence of the stimulus. The author treats the fact that both necessary conditions are satisfied as evidence that the sufficient condition must be true.

The question stem identifies this as a Parallel Flaw question. Our prephrase is that the argument in the stimulus was a flawed conditional argument in which the conclusion is derived by means of a Mistaken Reversal. Further, we can say that the argument consists of a conditional rule (in which there are two necessary conditions), a fact invoking the necessary conditions of the rule, and a conclusion stating that the sufficient condition of the rule must be the case.

Answer choice (A): This answer choice is incorrect because its conclusion is a valid application of the conditional rule to the facts. The rule describes three sufficient conditions for plants to thrive. We are told that if the plants have a lot of moisture, light, and nutrients then they will thrive. Then the answer tells us that greenhouses satisfy all three sufficient conditions, and the plants that you get from greenhouses are “so healthy,” meaning that they have thrived.

Answer choice (B): Here, the rule is that globalization of markets will enable each country to optimize its use of resources when every country has equal access to the markets. Then, we are told that every country will have equal access to markets in 20 years. Applying this fact to the rule, the conclusion is that globalization of markets will produce the optimal use of resources by each country 20 years from now. This conclusion is flawed, but not in the same way as the argument in the stimulus. Here, the conclusion is flawed because it treats the opportunity to optimize resource use with the optimization actually taking place. However, since the argument does not have the same logical structure as the argument in the stimulus, this answer choice is incorrect.

Answer choice (C): This is the correct answer choice, even though it has four rather than two necessary conditions. The rule in this answer is that if a business idea is viable, it must be clear, cost-effective, practical, and responsive to market demand. Based on evidence that a certain business idea satisfies each of the four necessary conditions, the argument concludes that the business idea is viable. Just like the conclusion in the stimulus, this conclusion results from the mistaken reversal of the rule.

Answer choice (D): This is a tricky incorrect answer choice because it contains a biconditional rule. The addition of the language “and only those” makes this rule biconditional, meaning that a mistaken reversal is impossible. We can diagram the rule as:

at least two years = have played the sport for at least the two years immediately preceding the competition

• Sufficient Necessary
  
  under 19 years of age
  
  +
  
  eligible for award be in secondary school
  
  +
  
  at least two years

The argument concludes that since the person has fulfilled each of the three necessary conditions, then the sufficient condition is true. Normally, this conclusion would be the invalid result of a mistaken reversal. However, because of the biconditional nature of the rule, in which the terms are both sufficient and necessary of each other, the conclusion is valid.

Answer choice (E): The conclusion in this answer choice is flawed, but for a different reason than the conclusion in the stimulus was flawed. Here, the rule is that for a meal to be nutritious, then it must include both carbohydrates and protein. The fact provided for the application of the rule is that nearly 80 percent of the calories in the person’s lunch were from fat. From this evidence, the argument concludes that the lunch was not nutritious. This conclusion is flawed, because the argument treats the evidence regarding the fat content of the food as meaning that the food did not contain both carbohydrates and protein. However, this is not necessarily the case. There are still 20 percent of the food’s calories unaccounted for, and those calories may have included both carbohydrates and protein.

[Cking14]

Hi,

I chose (D) for this question, but (C) is the correct answer. I don't really see a difference in the answer choices. Both list several attributes that must be present, and then end up concluding that, whatever the requirements are, since they have been met, then it must be true. What makes (C) better than (D) on this question?

Thanks,
Chris

[Robert Carroll]

Chris,

Note that the stimulus contains a Mistaken Reversal. Thus, you're looking for that in the correct answer choice.

Answer choice (C) contains that Mistaken Reversal - it says that a certain thing has the necessary conditions for a certain sufficient condition, then says the necessary conditions are fulfilled, and then goes on to conclude that the sufficient condition is fulfilled. Since I think you see that answer choice (C) contains the Mistaken Reversal it needs, I won't focus on it.

Instead, I'll explain what's wrong with answer choice (D). It does not contains a Mistaken Reversal. Instead, answer choice (D) says the following:

competitors meet the criteria eligible for the award

In other words, if we first ignore the phrase in the dashes, it says that anyone who meets the criteria is eligible. Thus:

competitors meet the criteria eligible for the award

The phrase in the dashes says that only those who meet the criteria are thus eligible. Thus:

eligible for the award competitors meet the criteria

The combination of these two conditionals is the double arrow that I gave at first. Thus, this argument does not contain a Mistaken Reversal.

Robert Carroll

[Cking14]

Thank you!

[LustingFor!L]

Can you diagram the Mistaken Negation for the stimulus?

[Kristina Moen]

Can you diagram the Mistaken Negation for the stimulus?

"The return of organic wastes to the soil is a good solution to waste disposal problems only if the wastes are nontoxic and not too much energy is expended in transporting them" can be diagrammed as:
Good solution Nontoxic and not too much energy expended in transporting them

A Mistaken Negation would be:
Not a good solution Toxic or too much energy expended in transporting them

A Mistaken Reversal would be:
Nontoxic and not too much energy expended in transporting them good solution.

Note that the Mistaken Negation and Mistaken Reversal mean the same thing. The Mistaken Reversal is the contrapositive of the Mistaken Negation.

[JulesC]

Hello,

I need some help on question 22 in the Section 2 (LR) of prep test 72, June 2014. I am confused on the conditional reasoning in this question and would appreciate an explanation.

Thanks,

Jules

[Rachael Wilkenfeld]

Hi Jules,

Let's take a look at this one. The first thing that jumps out at me is the "only if" language. It identifies a necessary condition, so I start with that relationship.

• wastes are non-toxic
  
  Returning organic waste materials to the soil is a good solution +
  
  not too much energy is expended in transport

The passage continues by small scale organic farm wastes are non-toxic, and don't take a lot of energy to transport. Therefore, the author concludes, returning organic waste to the soil is a good solution for those farms.

Immediately, we can recognize that the conclusion is them Mistaken Reversal of our original conditional statement. It just reversed the terms instead of reversing AND negating them.

Before we go into the answer choices, we know we are looking for that same error: Conditional reasoning, with a mistaken reversal or mistaken negation, as those two mistakes are logically equivalent. If an answer choice is not conditional, we don't even really have to draw it out at all.

Answer choice (A): This one involves causal reasoning, but talking about WHY something is occurring in the conclusion. That's a different reasoning type than we saw in the stimulus, so we can eliminate this answer choice.

Answer choice (B): We can eliminate this answer choice quickly, because the conclusion makes a logical leap apart from the conditional reasoning. We don't know what the desired results are here, so we can't draw any conclusion about if/when they will be reached.

Answer choice (C): This is the correct answer choice. Here, we see the same conditional structure and error.


Viable idea must be clear, cost-effective, practical and responsible.


Your idea is "all of those" which references the clear, cost-effective, practical and responsible condition, therefore, your idea is viable. The argument has the same flaw as our stimulus. Instead of reversing and negating the original conditional, they just reverse it.

Answer choice (D): This answer choice is actually a bi-conditional. "Those and only those" is logically equivalent to "if and only if." The arrow would go both directions, so there couldn't be a mistaken reversal here. We don't have to consider this any further.

Answer choice (E): This one looks like it might be possible, so we want to draw it out.


Nutritious contains carbohydrates + protein.


My meal was 80% fats, so it was not nutritious. The problem here is that we don't know that it didn't contain carbohydrates and protein. It very well might contain both carbohydrates and proteins in the other 20%. So this is not a mistaken reversal, but a different sort of error.

Notice that as soon as I hit a point in an answer choice where it didn't match the logical structure of the stimulus, I eliminated it. I didn't need to find all the reasons that an answer is wrong. As soon as it doesn't match, we eliminate it.

Hope that helps!
Rachael