LR Sufficient & Necessary Flashcards
When are sufficient and necessary combined? *This is rare
When they use the phrase “if and only if” (ex: if and only if you win the race you’ll get $500)
Sufficient rules
1) If I have it, I’m GUARANTEED to get the result If I’m in New York, I’m guaranteed to be in the USA
2) If I don’t have it, the result COULD happen If I’m not in New York I could be in the USA
Necessary rules
1) If I have it, the result COULD happen If I’m in the USA, I could be in New York
2) If I don’t have it, the result WON’T happen If I’m not in the USA, I won’t be in New York
What does the sufficient assumption do?
Adds an unstated premise (evidence) to prove the conclusion
What does the necessary assumption do?
Adds an unstated premise (evidence) that the argument needs to be true, or else it falls apart (does the author HAVE TO AGREE with my answer?)
Sufficient question examples
1) Which one of the following if assumed, would justify the conclusion?
2) Which one of the following, if assumed, enables the argument’s conclusion to be properly drawn?
3) The argument’s conclusion can be properly inferred if which one of the following is true?
4) The speaker’s main conclusion logically follows if which one of the following is assumed?
watch out for strong words: some & many in answers
Necessary question examples
1) Which one of the following is an assumption on which the argument depends?
2) The conclusion relies on which one of the following assumptions?
3) The argument presupposes which one of the following?
4) The conclusion doesn’t follow unless…
watch out for strong words: any, each, every, only, most in answers
Sufficient assumption question I missed on 12/3/24
In order to cut costs and thereby maximize his profit, Mr. Kapp used inferior materials in constructing the library. Whether legal or not, it was clearly wrong for him to do so. For, as an experienced and knowledgeable builder, he must have realized that his action would put people at serious risk.
The argumentʼs conclusion is properly drawn if which one of the following is assumed?
A) Any knowledgeable and experienced builder would realize that using the inferior construction materials that Mr. Kapp used would put people at serious risk.
B) An action can be wrong from a moral standpoint without necessarily being illegal.
C) Mr. Kapp made a large profit from the construction and sale of the building.
D) It is wrong to knowingly put people at serious risk for the sake of profit.
E) Mr. Kapp either knew or ought to have known that using the inferior materials he used to build the library would put people at serious risk.
Conclusion: it was clearly wrong for him to do so (1st sentence)
Rule: putting people at risk for profit is wrong
Consequence: putting people at risk
Test 153, Section 3, Question 18
Necessary assumption question I missed on 12/6/24
A recent study showed that the immune system blood cells of the study’s participants who drank tea but no coffee took half as long to respond to germs as did the blood cells of participants who drank coffee but no tea. Thus, drinking tea boosted the participants’ immune system defenses.
Level 5
Which one of the following is an assumption on which the argument depends?
A) All of the participants in the study drank either tea or coffee, and none drank both.
B) Coffee has no health benefits that are as valuable as the boost that tea purportedly gives to the body’s immune system.
C) In the study, drinking coffee did not cause the blood cell response time to double.
D) Coffee drinkers in general are no more likely to exercise and eat healthily than are tea drinkers.
E) Coffee and tea do not have in common any chemicals that fight disease in the human body.
Conclusion: Thus, drinking tea boosted the participants’ immune system defenses.
Test 143, Section 3, Question 19
Necessary assumption question I missed on 12/6/24
The populations of certain species of amphibians have declined dramatically in recent years, an effect many scientists attribute to industrial pollution. However, most amphibian species’ populations vary greatly from year to year because of natural variations in the weather. It is therefore impossible to be sure that the recent decline in those amphibian populations is due to industrial pollution.
Level 5
The argument depends on assuming which one of the following?
A) The amphibian species whose population declines have been attributed by many scientists to industrial pollution are not known to be among those species whose populations do not vary greatly as a result of natural variations in the weather. (pay attention to the double negatives, that’s why you missed this one)
B) The variations in amphibian species’ populations that result from natural variations in the weather are not always as large as the amphibian population declines that scientists have attributed to industrial pollution.
C) Either industrial pollution or natural variations in the weather, but not both, caused the amphibian population declines that scientists have attributed to industrial pollution.
D) If industrial pollution were reduced, the decline in certain amphibian populations would be reversed, and if industrial pollution increases, the decline in certain amphibian populations will be exacerbated.
E) If industrial pollution is severe, it can create more variations in the weather than would occur naturally.
Read carefully!
Conclusion: It is therefore impossible to be sure that the recent decline in those amphibian populations is due to industrial pollution.
Test 143, Section 3, Question 25
Sufficient assumption question I missed on 12/7/24
Ms. Sandstrom’s newspaper column describing a strange natural phenonmenon on the Mendels farm led many people to trespass on and extensively damage their property. Thus, Ms Sandstrom should pay for this damage if, as the Mendels claim, she could have reasonably expected that the column would lead people to damage the Mendel’s farm.
Level 3
The argument’s conclusion can be properly inferred if which one of the following is assumed?
A) One should pay for any damage that one’s action leads other people to cause if one could have reasonably expected that the action would lead other peope to cause damage
B) One should pay for damage that one’s action leads other people to cause only if (makes this a necessary condition & this would work if they were saying that Ms. Sandstrom doesn’t have to pay which is irrelevant to our conclusion), prior to the action, one expected that the action would lead other people to cause that damage
C) It is unlikely that the people who trespassed on and caused the damage to the Mendels’ property would themselves pay for the damage they caused
D) Ms. Sandstrom knew that her column would incite trespassing that could result in damage to the Mendels’ farm (this is missing the consequence of having to pay, you picked this because of your own bias not because of what the prompt was asking)
E) The Mendels believe that Ms. Sandstrom is able to form reasonable expectations about the consequences of her actions
The answer can reiterate what the passage says
Thought the real answer was saying the same thing as the passage & that’s okay!
Rule: expected that their actions would lead to damage
Consequence: she should pay
Test 133, Section 1, Question 10
Sufficient assumption question I missed on 12/7/24
Principle: When none of the fully qualified candidates for a new position at Arvue Corporation currently works for that company, it should hire the candidate who would be most productive in that position.
Application: Arvue should not hire Krall for the new position, because Delacruz is a candidate and is fully qualified
Level 4
Which one of the following, if true, justifies the above application of the principle
A) All of the candidates are fully qualified for the new position, but none already works for Arvue
B) Of all (imples there are qualified candidates at Arvue) the candidates who do not already work for Arvue, Delacruz would be the most productive in the new position
C) Krall works for Arvue, but Delacruz is the candidate who would be most productive in the new position (I initially read the principle wrong and understood it as saying that when there aren’t any qualified candidates at the company then we should find the person that would be most productive in the company. That’s why I initially chose this answer)
D) Several candidates currently work for Arvue, but Krall and Delacruz do not
E) None of the candidates already works for Arvue, and Delacruz is the candidate who would be most productive in the new position (rule & consequene: no fully qualified candidates working at Arvue, hire an outside candidate who would be most productive)
Read the principle wrong; break it down so simply next time
Test 143, Section 4, Question 19
Sufficient assumption question I missed on 12/12/24
Rocket engines are most effective when exhaust gases escape from their nozzles at the same pressure as the surrounding atmosphere. At low altitudes, where atmospheric pressure is high, this effect is best produced by a short nozzle, but when the rocket passes through the thin upper atmosphere, a long nozzle becomes more effective. Thus, to work most effectively throughout their ascents, all rockets must have both short nozzles and long nozzles on their engines.
Level 4
Which one of the following is an assumption the argument requires?
A) Equipping a rocket’s engines with both short and long nozzles is not significantly more difficult than equipping them with nozzles of equal lengths.
B) At some point during their ascents, all rockets will pass through the thin upper atmosphere.
C) A rocket with only short nozzles on its engines cannot reach high altitudes.
D) For a rocket to work effectively, its engines’ exhaust gases must leave the nozzles at the same pressure as the surrounding atmosphere throughout the rocket’s ascent.
E) For a rocket to work most effectively at both low and high atmospheric pressures, it must have at least one engine that has both a short nozzle and a long nozzle.
Test 143, Section 3, Question 17
Sufficient assumption question I missed on 12/18/24
An art critic, by ridiculing an artwork, can undermine the pleasure one takes in it; conversely, by lavishing praise upon an artwork, an art critic can render the experience of viewing the artwork more pleasurable. So an artwork’s artistic merit can depend not only on the person who creates it (this doesn’t need to be viewed as part of the conclusion because it’s not mentioned in the argument; only look at the following line) but also on those who critically evaluate it.
Level 3
The conclusion can be properly drawn if which one of the following is assumed?
(A) The merit of an artistic work is determined by the amount of pleasure it elicits. *the amount of pleasure art elicits determines the merit of that artwork; this connects the premise & conclusion
(B) Most people lack the confidence necessary for making their own evaluations of art.
(C) Art critics understand what gives an artwork artistic merit better than artists do.
(D) Most people seek out critical reviews of particular artworks before viewing those works.
(E) The pleasure people take in something is typically influenced by what they think others feel about it. *what I picked originally, this supports the argument not the conclusion. If they asked for a general principle then yea
Didn’t know I could overlook: depend not only on the person who creates
*Premise: Art critic can affect the pleasure the viewer gets
Conclusion: artwork’s artistic merit depends on those who critically evaluate it
Test 143, Section 4, Question 13
Sufficient assumption question I missed on 12/18/24
Critic: Photographers, by deciding which subjects to depict and how to depict them, express their own worldviews in their photographs, however realistically those photographs may represent reality. *Thus, photographs are interpretations of reality.
Level 3
The argument’s conclusion is properly drawn if which one of the following is assumed?
(A) Even representing a subject realistically can
involve interpreting that subject.
(B) To express a worldview is to interpret reality.
(C) All visual art expresses the artist’s worldview.
(D) Any interpretation of reality involves the
expression of a worldview. Initially picked this answer, was between this and B. This answer flipped what the answer should be. To be correct this would need to say, “the expression of a world view is an interpretation of reality.”
(E) Nonrealistic photographs, like realistic photographs, express the worldviews of the
photographers who take them.
P: photographs are expressions of photographers wouldviews
C: photographs are interpretations of reality
Test 142, Section 2, Question 13
