#19 - The recent concert was probably not properly promoted

[Administrator]

Complete Question Explanation

Parallel Reasoning. The correct answer choice is (C).

There are a number of elements to consider when you attack a Parallel Reasoning question. Are the conclusions the same? Are the premises the same? Does the answer use the same type of reasoning as the stimulus did, and did it follow the same structure? If the stimulus is a valid argument, then is the answer choice also valid? If the stimulus is flawed, does the answer choice contain that same flaw?

Tracking those elements here, we have clear conditional reasoning, indicated by the use of the word "unless." The conclusion is about probability, not certainty or mere possibility. The author relies on the opinion of a trusted expert as part of the premises. Diagramming this argument's conditional elements would look like this:

Premise (expert says): Sell Out Poorly Promoted

Premise: Sell out

Conclusion: Probably Poorly Promoted

This looks valid, if we trust the expert. It would have been flawed if the conclusion was absolutely certain that it was poorly promoted, because that would involve too much reliance on the expert, a flawed Appeal to Authority.

So, we need an answer that uses a conditional relationship, that is based on the opinion of a trusted expert or authority, which includes probability in the conclusion, and which appears to be valid (so it will be based either on a restatement form - the sufficient occurs and so the necessary probably does - or else on a contrapositive).

Answer choice (A): A close call, this answer has most of the elements we need. Where it goes wrong is in shifting from a highly skilled surgeon performing it properly to a claim that it was probably not performed properly. This would have been a match if the answer had said "probably not performed properly by a highly skilled surgeon."

Answer choice (B): The conclusion here is not based on a conditional relationship provided by a trusted expert. Instead, the conditional relationship is provided by the author, and the expert only provided a fact.

Answer choice (C): This is the correct answer choice. A trusted expert provides a conditional relationship with an element of probability to it, and the contrapositive occurs, with that element of probability in the conclusion. This matches all the key elements of the stimulus and is therefore the credited response.

Answer choice (D): A few problems here, most notably that the conclusion is about the expert being wrong, rather than trusting that they are probably right. Also, we are given no reason to trust this particular expert.

Answer choice (E): This answer is based on a Mistaken Reversal of the conditional relationship provided by the trusted expert. That is, the necessary condition (find lead in the soil) did occur, and the author concludes that the sufficient condition (properly conducted) probably occurred. The presence of the necessary condition is not proof that the sufficient condition occurred, and this flawed answer cannot be parallel to the valid one in the stimulus.

[carnegie49]

I'm really struggling with quickly and accurately doing the conditional diagramming for the pattern of reasoning questions (I have reviewed the Logical Reasoning Bible).

1. Could someone please explain how to approach this question/what the conditional logic is for the stimulus.

2. For answer choice C, how do I recognize that the "since one can still notice the damage" is the sufficient part of the conditional reasoning and the phrase 'repair to the wall probably was not properly done" is the necessary part? Is "since" always used to begin a sufficient phrase, or can it also be used on the necessary side?

Example: Since Jane lifts weights, she is stronger now. Since is part of sufficient clause

I can't think of an example that would put a phrase beginnign with "since" in the necessary side.

Many thanks!!

[David Boyle]

I'm really struggling with quickly and accurately doing the conditional diagramming for the pattern of reasoning questions (I have reviewed the Logical Reasoning Bible).

1. Could someone please explain how to approach this question/what the conditional logic is for the stimulus.

2. For answer choice C, how do I recognize that the "since one can still notice the damage" is the sufficient part of the conditional reasoning and the phrase 'repair to the wall probably was not properly done" is the necessary part? Is "since" always used to begin a sufficient phrase, or can it also be used on the necessary side?

Example: Since Jane lifts weights, she is stronger now. Since is part of sufficient clause

I can't think of an example that would put a phrase beginnign with "since" in the necessary side.

Many thanks!!

Hello,

There is a sort of repeat form going on here:

slash sell out poorly promoted
slash sell out not properly promoted

Answer C does a similar thing, though in a contrapositive way. (Properly repaired slash noticeable; noticeable: slash properly repaired)
"Since..." is seemingly not the sufficient part of the equation, then, in answer C, where it seems to be more the necessary part. (And with the Jane example you give, "since" may introduce causal reasoning more than conditional.)

Hope this helps,
David

[carnegie49]

I have a follow-up in response to the below posting by a Powerscore staffer:

Answer C does a similar thing, though in a contrapositive way. (Properly repaired slash noticeable; noticeable: slash properly repaired)
"Since..." is seemingly not the sufficient part of the equation, then, in answer C, where it seems to be more the necessary part.


--Contrary to the above statement, It seems to me that the phrase "since one can still notice the damage" functions as the sufficient, and not necessary, part of the conditional reasoning. That is, "since one can still notice the damage" is the sufficent phrase and the 'repair was not properly done' part is the necessary. This is the only way I can see to make the contrapositive be logically sound/match the 'properly repaird --> not noticeable logic. If the 'since' phrase is the necessary part, this would be a mistaken reversal, I believe.

Can you please clarify the sufficient and necessary components here AND how to recognize them in this case. I'm very confused.

Thanks.

[Emily Haney-Caron]

Hi carnegie,

I think starting from the beginning might help here. This is how I approached this question:
poorly promoted sell out
(and contrapositive: sell out poorly promoted)

We could also make this more abstract: Expert says A B
B
Therefore, probably A

We then want to match this reasoning to the answer choices.

A: expert says performed by skilled surgeon patient survives
(contrapositive: patient survives performed by skilled surgeon)
The logic here is: expert says A B
Therefore, B C
Instead of seeing a repeat of A, we get a new term. This one is out.

B: expert says probably organic compounds
Therefore, probably labeled correctly
Because labeled correctly organic compounds
The logic is: experts says A
Therefore, B
A B
This doesn't match at all. We have an expert who isn't giving us the conditional reasoning. It just doesn't match.

C: Expert says properly repaired noticeable
Therefore, probably properly repaired
Because: noticeable
The logic is: experts says A B
B
Therefore, probably A
This matches. This seems like the right answer, but I'm still going to check the other two.

D: expert says: damaged in storm require repairs
Require repairs (implied by roof leaking)
No storm expert wrong
This logic is very clearly not correct; it concludes the expert is wrong, rather than concluding something based on what the expert says.

E: tests proper find lead
find lead tests proper
Logic: A B
B A
Whoops; that is an incorrectly done contrapositive! We can cross this one out.

Hopefully this gives you a clearer sense of the diagramming for this question, and the role of "since." Let us know if you have additional questions!

[carnegie49]

Many thanks! I wasn't considering turning the logic into its contrapositive. Before rewriting my logic statement in the contrapositive, C did not some to parallel the logic sentence I wrote out for the simulus.

For the premise I wrote:

Not Sell Out --> Poorly Promoted not A --> B
Not Sell Out not A
Probably Poorly Promoted probably B

which did not seem to match what I wrote out for letter C:

Properly repaired --> Not noticeable A --> not B
Noticeable B
Probably not properly repaired not A

These statements did not seem logically parallel to me, but when I translated the logic from the stimulus into its contrapositive I could see how the pattern of reasoning is consistent. I'm just concerned about recognizing this under the time pressure/having to spend time writing out the logic sentence 2 different ways to account for my inability to recognize the contrapositive off the bat.

Thanks again.

[Clay Cooper]

Hi carnegie,

I understand your concern about quickly diagramming both versions of a conditional rule - it can be tough, especially before we become comfortable with the technique.

I would suggest that you try to establish a habit of routinely diagramming both versions of every rule you diagram at all. I encourage my students to 'turn your brain off' when diagramming the contrapositive version - I think that will help you save time. In other words, if we have:

A B,

we should automatically follow it up with its contrapositive. But, specifically, don't try to think your way through to the contrapositive; just make an almost mechanical habit of taking the term on the left, negating it without thinking about what that means, and placing it on the right, and taking the term on the right, negating it without thinking about what that means, and putting it on the left. What you will end up with is the contrapositive, every time. This method is quicker than trying to actually derive two versions of the same rule, and I think it will relieve some of the pressure you feel.

I hope that helps.

[lilmissunshine]

Hello,

I got the question right but was very confused when I tried to diagram the stimulus.

Premise: Sell out Poorly promoted
Condition: Sell out
Conclusion: Poorly promoted

Is this correct? Many thanks!

[Adam Tyson]

Looks perfect, lilmissunshine! You may be wondering, though, whether that is a problem, since your diagram is what we call a restatement (the sufficient happened, so the necessary happened) and the correct answer is a contrapositive (the necessary did not happen, so the sufficient did not happen). That's actually not a problem, though, because restatements and contrapositives are logically equivalent statements. We could just as easily have diagrammed the premise the other way around, like this:

Poorly Promoted Sell Out

If we had done it that way (which means exactly the same thing as your diagram, which followed our Unless Equation perfectly), then we would view the argument as being based on a contrapositive, just like the correct answer.

[alexisjay26]

The reasoning why C is correct is confusing to me.

I diagrammed 19 this way:
Premise: -SO —> PP
Premise: -SO
Conclusion: PP

This is valid inference.

I diagrammed answer C as:
Premise: PR —> -N
Premise: N
Conclusion: -PR

This is also a valid inference the only difference is this conclusion is based on the contrapositive of premise 1, with the contrapositive being:
N —> -PR

My issue is that the conclusion in the question stem is not based off the contrapositive of premise 1; it’s basically a restatement of the premise. I know that Dave above said if we had originally diagrammed the stem as
-PP —> SO (with the contrapositive being
-SO —> PP) then the conclusion in that scenario would be based off the contrapositive as well. However, given the unless equation that is not the way that I would originally diagram the stem. The unless equation tells me to diagram the conditional statement the way I originally did (-SO —> PP) How then would I be able to confidently say that C is the correct answer if answer C is technically based off of the contrapositive of premise 1 in that scenario and the scenario in the question stem is not.