#10 - Principle: People should buy an expensive antique

[Administrator]

Complete Question Explanation

Strengthen-Principle. The correct answer choice is (E).

We are presented with a conditional Principle (note the use of the phrase "only if" in the rule), and an application of that rule. The principle can be diagrammed as follows:

BEA (Buy Expensive Antique) CA (Confident of Authenticity) AND FPDIQ (Find Piece Desirable for Intrinsic Qualities)

In the application of the principle, we are told that Matilde should NOT buy the expensive antique, or:

BEAMatilde

In order to strengthen the application of the principle (and be aware that this is a Strengthen, not a Justify question, because the word "justify" in the stem is preceded by the qualifying phrase "most helps"), where the author has concluded that the Sufficient Condition should not occur, we want an answer that shows that a Necessary Condition may not have occurred. In this case, since there are two necessary conditions (CA AND FPDIQ), we need only show that one of those two may not have occurred. It will suffice to show that either Matilde cannot be confident in the authenticity of the piece, or that she does not find it desirable for its intrinsic qualities.

Answer choice (A): This answer indicates that Matilde might be confident about the authenticity of the piece due to her expertise. That's the opposite of what we were looking for, and is therefore a loser.

Answer choice (B): This answer suggests that Matilde is interested in the piece at least partially due to its value as an investment, but that does not mean that she does not also find it desirable for its intrinsic qualities. There is also nothing in this answer to suggest that she cannot be confident in its authenticity. The necessary conditions have not been questioned, so this does nothing to support the conclusion.

Answer choice (C): This answer indicates that Matilde does find the piece desirable for its intrinsic qualities, and it tells us nothing about her confidence in its authenticity, but only that the seller is willing to provide some evidence of that.

Answer choice (D): Don't read too much into this answer! Just because Matilde thinks the piece is under-priced does NOT mean that she is unsure about its authenticity. She might be confident, and very excited about the bargain she is about to get on something she finds desirable for its intrinsic qualities!

Answer choice (E): This is the correct answer choice. This answer indicates that although Matilde does find the piece desirable for its intrinsic qualities, she cannot be confident in its authenticity. That triggers the contrapositive and strengthens (and does so enough to justify) the conclusion that she should not buy the piece.

[fersian]

Hello. I noticed that this question hasn't been posted, but it is leaving me stumped.

CA - confident of its authenticity
FPDIQ - find the piece desirable for its intrinsic qualities
VI - value as an investment

I diagrammed the principle as: CA & FPDIQ & ~VI --> BEA
Contrapositive: ~BEA --> ~CA or ~FPDIQ or VI

Essentially, in order for the sufficient to work, we need one of the necessary conditions to trigger.
In answer choice 'C', which was what I selected, "suspects that it will be highly desirable to other collectors in the future" triggers the last necessary condition (VI).

Can someone help me as to where I went wrong? I did keep the credited response 'E' as my other contender.

Thank you.

[Adam Tyson]

You've made a mistaken reversal in your diagram, fersian - the key is the phrase "only if" in the stimulus, which indicates a necessary condition rather than a sufficient one. You spoke about the necessary conditions triggering the sufficient, but it's the other way around - a necessary condition doesn't trigger anything, but is itself triggered by (required by) the sufficient condition. The correct diagram should be:

BEA CA & FPDIQ

(the bit about value as an investment is not part of the conditional relationship, as the author is saying that the buyer should want it for more than just that. It's okay if they want it for its value as an investment, but they have to also find it intrinsically desirable.)

The author has concluded that Matilde should NOT buy the antique. That means we need to prove that the sufficient condition does not occur, and to prove that we use the contrapositive and look for an answer where at least some part of the necessary condition fails to occur. Answer E tells us that the authenticity cannot be confirmed (CA), and that's all we need!

As to answer C, it makes no difference whether Matilde is interested in the value of the antique as an investment. What matters is whether that is the ONLY thing she cares about, or if she also desires it for its intrinsic qualities. That answer tells us that she admires its shape and color, so that condition is met, and the contrapositive is NOT triggered by this information.

Use that "only if" as your guide to set up the diagram, and you'll be good to go!

[fersian]

Hi Adam,
Thank you very much for your explanation. It was very helpful!

[jupiterlaw]

Hi!

I am curious about how and when to know you can be confident about something applying to the "rule", I think I am missing something here.

I incorrectly chose B. I assumed that by saying she's not sure the value will appreciate in the future, that this = she ONLY desires the vase for the investment value, I understand now that this is NOT enough evidence of failing the condition that she desires the vase for its intrinsic qualities.

I understand that I can't assume that "Matilde is not sure that the vase will appreciate much in value in the future" means that she only desires the vase for its value as an investment.

However, following that same rule of making a false assumption, why can I assume in E that because "…its particular style has frequently been reproduced for the mass market, and the vase cannot be examined closely or authenticated over the Internet" that this means Matilde would not be confident in its authenticity? Maybe she is an expert at this and doesn't need to use the Internet to be confident in the authenticity of something.

Overall, and I've found this with previous stimuli, I'm having trouble understanding when we can/can't accept what appears to me to be assumptions.

Thanks!

[Amber Thomas]

Hi jupiterlaw!

Let's outline our principle:

Buy Expensive Antique --> Confident of Authenticity + Desirable for Intrinsic Qualities

~Desirable for Intrinsic Qualities OR ~Confident of Authenticity --> ~Buy Expensive Antique

Now, we have to apply this to the following: Matilde should not buy the expensive antique vase offered for sale on the internet.

So, to pre-phrase our answer, we can say that the vase either ~Desirable for Intrinsic Qualities, or Matilde is ~Confident of Authenticity, or both.

The reason Answer Choice E works is as follows: in order to buy an expensive antique, you must BOTH be confident of it's authenticity, AND like it for some intrinsic quality. While Matilde does like the vase for its color and features, she cannot be confident of its authenticity. Therefore, we haven't met both of our criteria for Buy Expensive Antique. This works for the contrapositive as well-- only one of our sufficient conditions needs to be met for the necessary condition to follow. We have ~Confident of Authenticity, therefore, we can guarantee ~Buy Expensive Antique.

Answer Choice B tells us that Matilde is confident in its authenticity, however, we are unsure as to whether or not she likes it for some intrinsic quality. Therefore, we cannot definitively say whether or not both of our necessary conditions have been met.

I hope this helps!

[jupiterlaw]

Hi Amber,

I understand what you are explaining but this isn't what I am confused about, it doesn't answer my question exactly.

I understand that in order to buy an expensive antique, you must both be confident of it's authenticity, and like it for some intrinsic quality, and I understand your explanation of how E does not satisfy both.

My question is, just because E states that "...the vase cannot be examined closely or authenticated over the Internet" how come we can assume that this means MATILDE won't be able to be confident in its authenticity on her own?

In other words, I am confused about how we can assume that if the vase can't be authenticated over the internet this means the buyer CANNOT be confident in its authenticity. This is where the disconnect lies for me. Nowhere in the stim does it say for someone to be confident in authenticity it must be able to be verified over the internet. I feel like an assumption is being made in E, that the vase is not able to be authenticated online = Matilde can't be confident in its authenticity, and we need to accept this assumption for E to be the right answer but based on what I've learned thus far this doesn't feel like a valid assumption to me.