#8 - A person who does not have both a high school diploma and a demonstrated competence in

[Administrator]

Complete Question Explanation

Parallel Flaw. The correct answer choice is (B).

The argument in this stimulus contains conditional reasoning. In order to be utterly clear about what the structure of the argument is, we should definitely diagram it.

The first sentence contains a premise, and it says that a person who does not have both of two things will not be licensed. We have to understand that not having both of two things means lacking one or the other. In other words, the sufficient condition of this conditional is an "or" statement. Diagrammed, we have:

(HS diploma OR competence in CPR) licensed

This is consistent with the first sentence - anyone lacking even one of those things will not be licensed as an EMT.

Continuing, the next premise gives us info about Marie - she has both a HS diploma and competence in CPR. So:

(HS diploma AND competence in CPR)Marie

That's the opposite of the sufficient condition of the first premise - in general, "A OR B" is the negation of "A AND B". When negating a statement involving the word "OR", the "OR" becomes "AND" and the individual components get negated. Thus, this premise indeed says that the sufficient condition of the first sentence is false, at least when it comes to Marie.

The conclusion now says that Marie will be licensed:

licensedMarie

Putting that together with the second premise:

(HS diploma AND competence in CPR)Marie licensedMarie

Because that connection negates both conditions of the first sentence, but doesn't change their order, it's a textbook case of Mistaken Negation. That's the problem with the argument! And since this is a Parallel Flaw question, we want an answer choice that also exhibits a Mistaken Negation.

Answer choice (A): The word "without" allows us to use the Unless Equation - whatever "without" modifies is the necessary condition of the conditional, and the rest of the statement should be negated to form the sufficient condition. When diagrammed:

can play piano well (excellent ear OR exceptional dexterity)

can play piano wellPaul (excellent ear AND exceptional dexterity)Paul

The shift from "OR" to "AND" is a problem with this argument, but we're trying to find a Mistaken Negation, and this is nothing like that, so it's out.

Answer choice (B): This is the correct answer choice. Again we can use the Unless Equation on the word "without":

effective foreign language teacher fluent in at least two languages

Now we have:

fluent in at least two languagesYessios effective foreign language teacherYessios

This is a Mistaken Reversal, which is equivalent to a Mistaken Negation (each is the contrapositive of the other).

Answer choice (C): As with the two previous answer, we can use the Unless Equation:

licensed apprenticeship

licensedMartin apprenticeshipMartin

This is not even a flaw, but instead a good argument, so it's out.

Answer choice (D): As before, the Unless Equation is applicable:

effective mayor (knowledge of national AND knowledge of international)

effective mayorLeroux (knowledge of national AND knowledge of international)Leroux

This is another good argument and therefore a bad answer.

Answer choice (E): The phrase "the only" can be confusing. "Only" is always a necessary condition indicator. But what is "only" applying to in this answer choice? It's "fresh vegetables". After all, what is the "only way" to make delicious vegetable soup? Fresh vegetables. Therefore, "fresh vegetables" is the necessary condition. Diagramming:

delicious soup fresh veggies

delicious soupthis fresh veggiesthis

There's no Mistaken Negation or Mistaken Reversal here, so this answer choice cannot be correct.

[sarahof@berkeley.edu]

I got this one right during my practice test, but now upon reviewing I am a bit confused.

I believe the following is how the stimulus should be mapped out:

Stimulus: if a person does not have a high school diploma AND does not have a demonstrated competence in the techniques of cardiopulmonary resuscitation ---> that person will not be licensed as an emergency medical technician
Marie has high school diploma AND demonstrated competence --> she will be licensed

This appears to be a mistaken negation where the not is removed from the above mapped stimulus

But now I cannot see how this lines up with the correct answer choice B. Can someone help me figure out why B is the correct answer?

[atierney]

Hi Sarah,

I agree with your analysis of the stimulus. Turning to answer choice B, we have if not fluent in at least two languages ---> then not effective foreign language teacher. This, in turn, is negated to conclude if fluent in at least two languages ---> then effective foreign language teacher. Because this has the same mistaken negation error, it is the correct answer.

Let me know if you have further questions on this.

[sarahof@berkeley.edu]

Hi atierney,

Thank you for replying back. So, just to double check now, for answer B I mapped it as:

if possible to be effective --> fluent in at least 2 languages [using the unless rule]

So the contra-positive of that would be: if not fluent in at least 2 languages --> not possible to be effective

which is then where we see the negation is that correct? So we use the contrapositive?

[Adam Tyson]

Hey Sarah, let me start with a clarification of one thing from your original diagram, and that is that the sufficient conditions of "diploma" and "competence" should be connected with an OR rather than an AND. That is, if you don't have a diploma, that is enough to prove you cannot get licensed as an EMT, and if you aren't competent then you also cannot get licensed. Being licensed requires that you have both of those things, so missing just one or the other will disqualify you.

That didn't matter in this case, because the argument was still flawed due to a Mistaken Negation, as you described. A Mistaken Negation occurs whenever the argument says that because the Sufficient Condition did not occur, the Necessary Condition must also not occur.

A Mistaken Reversal occurs whenever the argument says that the Necessary Condition occurred and therefore the Sufficient Condition must occur. If you diagram out a Mistaken Negation and a Mistaken Reversal you will see that those two flaws are the contrapositive of each other, which means the two flaws are logically identical! That means you can generally treat them as interchangeable! So if we view the stimulus as having a Mistaken Negation, and we see the answer as having a Mistaken Reversal, those two are still the same flaw. Neat, huh?

Good work!

[emilyjmyer]

How is choice E not a mistake reversal?

I thought it would be diagrammed like use fresh vegetables--> delicious soup and then delicious soup--> use fresh vegetables?

Thanks!

[emilyjmyer]

How is choice E not a mistake reversal?

I thought it would be diagrammed like use fresh vegetables--> delicious soup and then delicious soup--> use fresh vegetables?

Thanks!

I thought that because of the presence of the word "only"

[Adam Tyson]

Answer E uses the tricky phrase "the only," emilyjmyer, and while that phrase does indicate a necessary condition, it does so somewhat indirectly. The necessary condition will not immediately follow that indicator phrase, which can cause some confusion.

To see what is necessary in this answer choice, answer this question: what is the only way? Here, "the only way" is to use fresh vegetables. That means fresh vegetables are what's necessary, and the sufficient condition is making a delicious vegetable soup. This answer is therefore not based on a mistaken negation; it's what we call a restatement, which is a claim that a sufficient condition happened and that therefore a necessary one must also happen. Restatements are valid, not flaws, and so this cannot be parallel to the flawed argument in the stimulus!