Self-study
People who receive unsolicited advice from someone whose advantage would be served if that advice is taken should regard the proffered advice with skepticism unless there is good reason to think that their interests substantially coincide with those of the advice giver in the circumstance in question.
Analysis of Principle
Something that makes this stimulus tricky is how wordy it is, which is often a sign that we need to kick a condition up to the domain. A good way to recognize which conditions to "kick up" is to ask which ones leave us unable to conclude anything if they aren't fulfilled.
So in this case, the condition we want to kick up to the domain is "receiving unsolicited advice from someone whose advantage would be served if that advantage is taken." If any answer choice starts talking about someone receiving solicited advice, or receiving advice from someone whose advantage would not be served if that advice is taken, then we can get rid of it right away, because we don't know anything about what happens in those situations. Those situations are outside the domain of this principle.
Now that we've established the domain where this principle applies, we have a much simpler conditional on our hands. Someone receives unsolicited advice from someone whose advantage would be served if that advice is taken (the domain). Such a person should view the advice with skepticism unless they have a good reason to think their interests coincide with the advice giver's interests. If we diagram this (remember how to diagram "unless"), we get:
/good reason to think interests coincide → skepticism
By the contrapositive: /skepticism → good reason to think interests coincide
This is the structure we expect to see in a valid application of the principle in the stimulus. So our thought process for each answer choice should be:
1. Does this answer choice fit the domain of the principle (i.e., is someone receiving unsolicited advice from someone who would benefit from that advice being taken)?
2. If yes, does the answer choice follow the structure of the principle? (i.e., if the person does not view the advice with skepticism, do they have a good reason to think their interests coincide with the advice-giver's? Or, if they don't have such a reason, do they view the advice with skepticism?)
If we can answer "yes" to both questions, we've found the correct answer choice.
19.
This principle, if accepted, would ███████ █████ ███ ██ ███ █████████ ██████████
a
After learning by ██████ ████ ███████ ██ ███████ ███ █ ██████ ██████████ ███ ███ ██████████ ████████ █████ ██████ ██ ███ ████████████ ███ ███ ███████ ██ ██ ██████████ ██████ ███████████ ███ █████ █████ ██ ███ ████ █████ ██ ████ ███████ ██████ ██████ ███ ██████ ███ ██ ████ ███ ██████ ███ ███████ ██████████
Incorrect. This situation fits the domain of the principle: Floyd is offering Harriet unsolicited advice, and he would benefit from her taking the advice. But the conclusion that Harriet should therefore simply reject Floyd's advice "out of hand," without telling us anything about whether Harriet has good reasons to believe her and Floyd's interests overlap, doesn't fit the principle. Notice that even if we knew Harriet did not have any reason to believe her and Floyd's interests coincided, the principle would only let us conclude that Harriet should be skeptical of Floyd's advice, not that she should definitely reject it.
b
While shopping for █ █████████████ ██████ ██ ██████████ ██ █ ███████████ ████ ██ ███ █████ ██ ███ ████████ ███████████ █████ ███ ███████ ███ █████ █████████ ██████ ████████ ███ ███████████████ ██████████ █████████ ████ ███ █████ ██ ███ ████████████ █████ ██ ██████ ██████ ███ ██████ ███ █████ █████████ █████ ██ ███ ███████████████ ██████ ██████
Correct. This situation fits the domain of the principle: Ramón has received unsolicited advice from someone who would benefit from his taking that advice. The answer choice concludes that Ramón should not take action "on the salesperson's advice alone": i.e., without additional information beyond the salesperson's advice, including whether his interests might also be served by following this advice, Ramón should be skeptical of this advice. So (B) fits the structure of the principle we diagrammed:
/reason to think interests coincide → skeptical
c
Mario wants to █████ ██████ ██ ██████████ ██████ ███ ████ ██ ████████ ███ ██████ ████████ ████ ██ █████ ███ ████████ █████████ █████ ████████ ████ ███ █████ ███████ ████████ █████ ██████ ████ ███████ █████ ████████ ██ ███ █████ ███████ █████ █████ ██ ████ ██ █████ ████ ██████ ██████ █████████ ███ ███████████████
Incorrect. We can reject (C) right away, because it doesn't fit the domain of our principle. Mario has asked Yvette for advice, meaning this advice is solicited. The principle in the stimulus is only about unsolicited advice.
d
Sara overhears Ron ███████ █████ █ ██████ ██ ████ ██ ████████ ███ ██████████ ██ █████████ █ ████████ ███ ███ ███████ ████████ ████ ██████ ████ ███ ███ ████ █████ █ ███████ ██ ████ █████████ █████ ███ ████████ ██████ ██ █ ████████ ██████ ██ █████████ ███ ██████ ███████████ ███████ ██████ ████████ ███████ ██ ██ ███ ████ ████████ ███ ███ ███████
Incorrect. This is a tricky answer choice because it tracks well with the questions we raised in our analysis. This situation fits the domain of the principle: Sara is offering unsolicited advice about which textbook to use, and she would probably benefit from Ron following that advice, since she wrote a chapter in the textbook and the book's editor is a friend of hers.
But the difficulty is that Ron's interests overlap with Sara's: he also wrote a chapter of the textbook. The stimulus never defines what it means for interests to coincide "substantially," but it seems like Ron stands to benefit about as much as Sara from this textbook being used, since they both wrote a chapter.
It's also not clear whether Sara's friend benefiting counts as Sara also benefiting, and how that benefit compares to the benefit coming from having written a chapter in the textbook. So in this case, the possibility that Ron's and Sara's interests overlap substantially, which Ron would likely be aware of, means we can't conclude for sure that Ron should be skeptical of Sara's advice.
(As a contrast, look at (B), where the conclusion is based on the hypothetical situation of Ramón relying only on the salesperson's advice, and so definitely not having additional information about whether their interests coincide.)
e
Mei is buying ████ ███ █████ █████ ███ ████ ███ ████ ██████ █████ ███ ██ █ ███████ ███ ██████ █████████ ████████ █ ████ ████ █████████ ████ ████ ███ ████ ███ ███████ ████████ █████ ██ ███ ███████ ████████ ███████ ████ ████ ████ ████ ██████ ██ ███ ████ ████ ██ █████ ████ ██████████ ███ ██████ ██████ ███ ███████████████
Incorrect. Like (C), this doesn't fit the domain of our principle. The stimulus only tells us about situations where someone offers unsolicited advice and would benefit from that advice being followed. In this case, while Joel offers unsolicited advice, it seems that he would not benefit from that advice being followed. So the principle doesn't apply to this situation.