Summary
The stimulus can be diagrammed as follows:
Notable Valid Inferences
If a motor is sound-insulated, it can be used in institutional settings.
No motors manufactured by EM Industries are sound-insulated.
Some motors that can be used in institutional settings are not manufactured by EM Industries.
No motors manufactured by EM Industries are sound-insulated.
Some motors that can be used in institutional settings are not manufactured by EM Industries.
A
If a motor can be used in institutional settings, then it is sound-insulated.
Could be false. While we know that every sound-insulated motor can be used in institutional settings, we do not know whether every motor that can be used in institutional settings is sound-insulated. (A) confuses the necessary and sufficient conditions.
B
None of the motors manufactured by EM Industries are sound-insulated.
Must be true. As shown below, by chaining the conditional claims, we see that “not made by EM Industries” is a necessary condition of “sound-insulated”.
C
At least some of the motors manufactured by EM Industries can be used in institutional settings.
Could be false. We know that some of the motors manufactured by EM Industries can’t be used in institutional settings, and it’s quite possible that all of them can’t!
D
If a motor is quiet enough to use in home appliances, then it is sound-insulated.
Could be false. While we know that every sound-insulated motor is quiet enough to use in home appliances, we do not know whether every motor quiet enough for home appliances is sound-insulated. (D) confuses the necessary and sufficient conditions.
E
None of the motors manufactured by EM Industries can be used in institutional settings.
Could be false. We know that some of the motors manufactured by EM Industries can’t be used in institutional settings, but it’s possible that some can. There might be sufficient conditions for institutional use other than sound-insulation.
Summary
The stimulus can be diagrammed as follows:
Notable Valid Inferences
If it is acceptable to intentionally misrepresent one’s beliefs, then you must be doing so in their interest.
A
Ann told someone that Bruce thought the Apollo missions to the moon were elaborate hoaxes, even though she knew he did not think this; she did so merely to make him look ridiculous.
This must violate the principle. Ann is not acting in Bruce’s interest, but she does misrepresent his beliefs. The sufficient condition of the rule (/person’s interest) is met, but the necessary condition (/intentionally misrepresent) is not, so this violates the rule.
B
Claude told someone that Thelma believed in extraterrestrial beings, even though he knew she believed no such thing; he did so solely to keep this other person from bothering her.
This is consistent with the principle. Claude intentionally represented Thelma’s beliefs, and he did so in her interest.
C
In Maria’s absence John had told people that Maria believed that university education should be free of charge. He knew that Maria would not want him telling people this, but he wanted these people to think highly of Maria.
The rule does not apply. In this situation, we don’t know Maria’s true beliefs––we just know that Maria wouldn’t want John to tell people that she thought education should be free. Because of this, we don’t know if John misrepresented her beliefs, intentionally or not.
D
Harvey told Josephine that he thought Josephine would someday be famous. Harvey did not really think that Josephine would ever be famous, but he said she would because he thought she would like him as a result.
The rule does not apply. In this situation, Harvey is misrepresenting his own beliefs; the rule applies to situations about misrepresenting another person’s beliefs.
E
Wanda told people that George thought Egypt is in Asia. Wanda herself knew that Egypt is in Africa, but she told people that George thought it was in Asia because she wanted people to know that George knew little about geography.
The rule does not apply. We don’t know whether or not George actually thought Egypt is in Asia, so we don’t know if Wanda was misrepresenting George’s beliefs.
"Surprising" Phenomenon
Between 1840 and 1860, why did the family fail to enjoy an increase in prosperity that corresponded to their increase in wool-income, which derived from the family’s increase in amount of wool sold internationally?
Objective
The correct answer should tell us about something that changed over 1840 to 1860 that might have led the family to either make less money or have greater expenses.
A
At the end of the 1800s, prices in general in Australia rose more rapidly than did the wholesale price of wool sold domestically.
What happened at the “end of the 1800s” won’t explain what happened to the family between 1840 and 1860. And, the family’s wool-income increased from international sales, so general prices increasing faster than domestic wool prices increased has no impact.
B
The prices of wool sold to domestic markets by Australian sheep farmers decreased dramatically during the period in question.
The family’s wool-income increased due to greater international sales. Even if the family made less wool-income from domestic sales, we already know their overall wool-income increased because of international sales.
C
The international and domestic prices for mutton, sheepskins, and certain other products produced by all Australian sheep farmers fell sharply during the period in question.
If prices for these non-wool products sold by the family fell sharply, that could have offset the increased income from wool-sales. This shows why overall income for the family might not have increased, even if wool-income did.
D
Competition in wool sales increased during the period in question, leaving Australian wool producers in a less favorable position than previously.
Even if Australian wool producers in general were in a less favorable position than previously, we already know this family increased their wool-income. This answer doesn’t suggest why the family’s prosperity might not have increased along with their wool-income.
E
Among Australian sheep farmers, the percentage who made their living exclusively from international wool sales increased significantly during the period in question.
We already know this family increased its wool-income from international sales. Whether other farmers exclusively sold internationally doesn’t tell us why this particular family might not have seen an increase in prosperity along with its increase in wool-income.
Summarize Argument
The lawyer concludes that it was not wrong for Meyers to take the compost. She supports this by saying that if you take something that you have good reason to think is someone else’s property, then you are stealing, and stealing is wrong. But Meyers did not have good reason to think that the compost was someone else’s property.
Identify and Describe Flaw
This is the cookie-cutter flaw of confusing necessary and sufficient conditions. The lawyer treats “good reason” as necessary for “wrong,” but according to her premises “good reason” is merely sufficient. So negating “good reason” tell us nothing about “wrong.”
In other words, even though Meyers had no good reason to believe that the compost was someone else’s property, it might still have been wrong to take it. Having “good reason” is not necessary for making something stealing or for making something wrong.
In other words, even though Meyers had no good reason to believe that the compost was someone else’s property, it might still have been wrong to take it. Having “good reason” is not necessary for making something stealing or for making something wrong.
A
confuses a factual claim with a moral judgment
The lawyer discusses both a factual claim about Meyers having no reason to believe that the compost belonged to anyone and a moral judgment about Meyers’ action not being wrong. But she never confuses these two claims.
B
takes for granted that Meyers would not have taken the compost if he had good reason to believe that it was someone else’s property
The lawyer doesn’t consider or make any assumptions about what might have happened if Meyers had good reason to believe the compost was someone else’s. She only discusses the fact that Meyers did not have a good reason to believe this.
C
takes a condition that by itself is enough to make an action wrong to also be necessary in order for the action to be wrong
Having “good reason...” is sufficient to make an action stealing, and thus to make it wrong. But the lawyer treats “good reason” as necessary. Just because Meyers had no good reason to believe that the compost belonged to someone else doesn’t mean that taking it was not wrong.
D
fails to consider the possibility that the compost was Meyers’ property
If the compost was Meyers’ property, this would strengthen the lawyer’s conclusion that it wasn’t wrong for him to take it.
E
concludes that something is certainly someone else’s property when there is merely good, but not conclusive, reason to think that it is someone else’s property
The lawyer concludes that it wasn’t wrong for Meyers to take the compost because he had no good reason to believe it was someone else’s property. She doesn’t conclude that the compost is certainly someone else’s property, nor does she give reason to think that it is.
Summary
The author concludes that predatory pricing should be acceptable.
Why?
Because even after the competitors of a company that practices predatory pricing go out of business, the threat of renewed competition will prevent the company from raising prices to unreasonable levels.
Why?
Because even after the competitors of a company that practices predatory pricing go out of business, the threat of renewed competition will prevent the company from raising prices to unreasonable levels.
Notable Assumptions
The author assumes that if predatory pricing doesn’t lead a company to raise prices to unreasonable levels, then it should be acceptable.
The author assumes that there are no negative effects from predatory pricing that would justify not allowing it to occur.
The author assumes that there are no negative effects from predatory pricing that would justify not allowing it to occur.
A
Any company that is successful will inevitably induce competitors to enter the market.
The concept of a “successful” company has no place in this argument. Also, the premise refers to the “threat” of renewed competition preventing prices from rising to unreasonable levels. This doesn’t require that competition actually resume.
B
It is unlikely that several competing companies will engage in predatory pricing simultaneously.
Not necessary, because even if several companies engage in predatory pricing at the same time, it could still be that one of the companies ends up prevailing. That company won’t raise prices to unreasonable levels.
C
Only the largest and wealthiest companies can engage in predatory pricing for a sustained period of time.
The concept of “largest and wealthiest companies” has no place in the reasoning of this argument.
D
It is only competition or the threat of competition that keeps companies from raising prices.
Not necessary, because if there were other things that kept companies from raising prices besides just competition or the threat of competition, that wouldn’t undermine the argument. In fact, that would just be another reason prices won’t rise to unreasonable levels.
E
Any pricing practice that does not result in unreasonable prices should be acceptable.
Necessary, because if it were not true — if there were some pricing practices that don’t result in unreasonable prices that still should NOT be acceptable — then the fact predatory pricing does not lead to unreasonable prices would not be enough to call predatory pricing acceptable. (E) is the author’s assumed connection from the premise to the conclusion.
Pediatrician: Swollen tonsils give rise to breathing problems during sleep, and the surgical removal of children’s swollen tonsils has been shown to alleviate sleep disturbances. So removing children’s tonsils before swelling even occurs will ensure that the children do not experience any breathing problems during sleep.
Summarize Argument
The pediatrician concludes that removing children’s tonsils before they swell will prevent all breathing problems during sleep. She supports this by saying that swollen tonsils cause breathing problems during sleep, and removing them alleviates sleep disturbances.
Identify and Describe Flaw
The pediatrician assumes that swollen tonsils are the only cause of breathing problems during sleep, ignoring other possible causes like asthma or allergies. If these other issues are involved, removing tonsils might not ensure that children don’t experience any breathing problems during sleep.
A
relies on an inappropriate appeal to authority
The pediatrician doesn’t rely on an appeal to authority at all. She notes that removing tonsils “has been shown” to alleviate sleep issues, but we don’t know that this is an appeal to authority and we certainly can’t assume that it’s an inappropriate one.
B
relies on an assumption that is tantamount to assuming that the conclusion is true
This is the cookie-cutter flaw of circular reasoning, where the argument assumes what it sets out to prove. The pediatrician doesn't make this mistake. She provides distinct premises to support her conclusion.
C
infers from the fact that an action has a certain effect that the action is intended to produce that effect
The pediatrician states that tonsil removal alleviates breathing issues during sleep, but she doesn't conclude that tonsil removal is intended to alleviate these issues. Instead, she concludes that it will alleviate all breathing problems during sleep.
D
fails to consider the possibility that there may be other medical reasons for surgically removing a child’s tonsils
The pediatrician doesn’t assume that alleviating breathing issues during sleep is the only reason to remove children’s tonsils. Instead, she assumes that swollen tonsils are the only cause of these breathing issues.
E
fails to consider the possibility that some breathing problems during sleep may be caused by something other than swollen tonsils
The pediatrician assumes that swollen tonsils are the only cause of the breathing problems, without considering other potential causes like allergies or asthma. If there are other causes, tonsil removal might not ensure that children don’t experience any breathing problems.