Feedback: there is no link to the lecture from Prof. Dan Epps at the end of the lesson. Fix this please, we'd like to hear it!

if you were confused about the explanations for (D), here's Gemini's version, which makes more sense:

Option (D) tries to make you think, "Ah! The counselor is confused because harsh criticism actually gives someone a motive to avoid the critic, not a motive to do the self-improvement/change!"

The stimulus mentions that harsh criticism is unpleasant, which naturally makes a reader think about avoidance behaviors. Psychologically, humans are motivated to avoid pain (unpleasant criticism) and do things that bring pleasure.

if you chose (E) like I did and wander why it turned out to be wrong, here's my take with a benefit of hindsight;

conclusion descriptor:

(1) arguing that a type of human cognition is unreliable

actual conclusion:

any history book gives only a distorted view

the conclusion is about the product of perception, not perception itself; just like the major premise (accurate conception of one’s physical environment);

(2) in one instance

the product of perception is unreliable not because of the instance as is, but because the perception was too brief (a single momentary perception); i.e. you didn't see the gas leak (upon a single momentary perception), but you could have smelled it/heard the hissing if you had more time to examine the pipe;

(3) because it has been shown to be unreliable

the major premise (One cannot frame an accurate conception of) technically did not show anything, it simply asserted unreliability; my gas leak example above, on the contrary, somewhat showed it;

(4) under similar circumstances

the circumstances (writing a history book/looking in the past) are technically not similar to one’s physical environment; what is similar though is the process or reasoning about the environment/history;

Completely out of nowhere: a super insightful deep dive into negation of quantifiers. Thank you, I loved this session.

using set framework to eliminate (C):

the argument reasons about a specific subset of "exceptionally long hours"

(C) reasons about the entire superset of hours, "exceptionally long" and normal/"short" hours as well

we can eliminate (C) on the grounds of being too strong and hence unncecessary

humbly offer my feedback on the explanations: set framework seems to be really going against the grain applied to this question;

conclusion:

/preserved -> /developed

prediction:

undiscovered substances are unique

(A) undiscovered substances are unique in relation to the substances that have already been discovered;

(A) is interesting because it cuts so deeply into the set that we've outlined as our prediction, but that doesn't seem to do much with the framework of sets;

J.Y.'s explanations on (E) when it's an NA question:

"If we were to swap out the question stem for a Strengthen or PSA then (E) and not (B) would be correct."

J.Y.'s explanations on (E) if it were indeed a PSA question:

"I mean WHO CARES, RIGHT? (E) is UTTERLY irrelevant. Okay, Colette had this noble purpose to explore moral questions. Grated! Too bad that her novels doesn't show this. I mean WHAT DOES (E) HAVE TO DO WITH ANYTHING? The conclusion doesn't care about Colette's intentions. The conclusion is concerned with the fairness of the claims about her novels. (E) built a bridge between Colette's intentions and some important moral questions. SO WHAT? What do I do with this?! Does this mean that the novels CARE about those important questions? We don't know. (E) is ABSOLUTELY irrelevant."

if you chose (E) like I did, note that it builds a bridge over the existing premise ("Such emotional crises almost invariably raise important moral questions."), i.e. between crises and questions, not over the assumption gap (the gap between questions and /indifference); even if you have (E), in order to get to the conclusion you will still have to further assume (albeit with more confidence) that raising moral questions somehow rule out indifference; furthermore, the premise ("Such emotional crises almost invariably raise important moral questions.") is stronger than (E) (Colette's purpose), because it confirms the outcome (Colette's intention does not guarantee the outcome); so (E) is redundant;

(B) builds the bridge over the assumption gap (between moral questions and indifference); if (E) is true and (B) is false, the argument IS invalid (indeed Colette had this purpose, and indeed the important moral questions were raised, too bad that the novels can still be indifferent to those questions);

well, if there is the ultimate promo of the upgrade, it's this free video; I absolutely loved it: it's insightful, it's to the point, and the selection of questions is just brilliant. You can't wait to compare your line of thinking with Eric's or the participants. Thank you, color me tempted to upgrade.

JY's explanation may have its merits for a blind review, but not as a valid approach to this question. For me personally "recap the stimulus in your own words" worked wonders.

tl;dr: try to pindown the idea in the stimulus in your own words right after you've finished reading and before starting to diagram.

What's the idea of the argument? The more one knows about history, the more morally blunt one becomes. Causal relationship is intuitively central here, not probabilistic (likely/unlikely).

So what causes the disenchantment of someone who starts off with "unambiguous moral beliefs"? [we plug in our real-world examples here] History is essentially an endless string of bloody wars, and betrayals, murders, assassinations, and injustices. Think Rome, think Shakespeare. The more you know, the more you understand historic figures, their motives and their circumstances, the less you judge them. It's a simple idea wrapped up in lsatspeak.

Once you take hold of the idea, these abstract components are pigeonholed:

p1: higher [moral] standards -c (enables)-> see more [moral aspects]

p2: read more -c-> judge less

c: read more -c-> see less

expectation: judgement must be necessary for something that enables us to see moral aspects (less judgement causes us to see less), so:

judge less -c-> something (judgement causes something) OR

something -> judgement (judgement is necessary for something)

Approaching it from the other end is a recipe for disaster. It's hard to grasp the meaning of the abstract components in the stimulus, let alone abstract probabilistic connections between them (likely/unlikely, more/less). But once you have the big picture, you can slap the labels on them more confidently (e.g. knowledge of history increases = read more), and you won't lose track, because you know what you're looking for (judgement causes comething that's necessary, judgement is necessary for something; you'll see that there is only one AC that directly links judgement to something else).

note on the text version of the lesson:

Answer choice D

"The conclusion makes a claim about the set of consumers who don't bother acquiring such information. That they are behaving irrationally."

that's not what the conclusion claims:

"Therefore, consumers who do not bother to acquire such information are thereby behaving rationally."

some food for thought for those who chose (B) like I did: kick "promise of love" (marital vow) into the domain, and things will start to make sense

sub-premises:

sp1: feeling --> /control

sp2: /control --> /sense

sub-conclusion:

feeling --> /sense

main conclusion:

feeling -?-> shouldn't

(D) /sense --> shouldn't

(B) promise and /control --> shouldn't

Think of a couple that has already made a vow. Now let's assume they do interpret love as a feeling. In this case the argument + (B) allows them to conclude: 1) they shouldn't have made this promise to each other (B); 2) that their promises make no sense (the argument). The argument + (D) on the other hand allows them to conclude that they shouldn't interpret the vow like a promise of a feeling, thanks to the missing piece supplied by (D): /sense --> /feeling.

H/T to J.Y. for selecting this question for our core curriculum. It turned out to be rather thought-provoking.

did someone get through the text explanations? any idea what this peace supposed to mean?

Answer Choice (C) ...

"This is the same bait laid out in (B). (C) is also baiting to commit the sufficiency necessity error. To conclude that Penn should not receive the award because Franklin failed one of the conditions in Rule 2."

very motivating indeed, thank you!

@jyoti_sh_n

You seem to be conflicted between (A) and (B) because you reason about what you are reading into the form, not about the form/structure itself.

(B)

the stimulus says hiccups --> ebola; (B) says ebola <--some--> /hiccups. (B) wants to pass as a contradiction to hiccups --> ebola, but it's not. If you simply add ebola <--some--> /hiccups to the stimulus, nothing will change. (B) targets those, who confuse necessity for sufficiency; those will see (B) as a counterexample.

(A)

the stimulus says other Ebola symptoms are mentioned, but it never clarifies how many; we reasonably assume that enough to be relevant and mentioned by the author; (A) blocks that reasonable assumption. Without this assumption the information about the accounts gives far less support for the conclusion.

Hope that helps.

tl;dr: If you chose (B) (like I did), you've failed to adhere to the framework (premise to conclusion bridging);

domain: level, straight stretches of roadways [within govt purview!]

P1: (speed limit = average speed) --> fewer accidents

P2: average speed = 75 km/h

P --> C? (the missing bridge)

C: speed limit = 75 km/h

(B) baits you to see unjustified scope shift in the conclusion (unwarranted generalization to i) "uniform national speed limit" ii) "all such roadways"; but if you look closely, the conclusion just spells out reasonable assumptions about the scope:

"A government study [OF [ALL?] NATIONAL ROADWAYS] indicates that raising speed limits to reflect the actual average speeds of traffic [i.e. UNIFORMLY, NO EXCEPTIONS] on level, straight stretches of high-speed roadways [i.e. ALL ROADWAYS, NO EXCEPTIONS] reduces the accident rate."

"if valid, most helps"

(B) requires at least 3 assumptions to work (to bridge the conclusion)

1. govt believes the results of the study

2. govt should act upon those results;

but why? (even if they trust the conclusions of the study)

3. govt wants to reduce the number of accidents OR

govt just should implement (blindly) the measures proposed (let's assume the study actually proposes the measures) in every study (on reduction of traffic accidents, if you will) they do and they trust

(E) spells out the biggest assumption required by (B)

i.e. that the action should be taken

bridging framework:

P1: (speed limit = average speed) --> fewer accidents

P2: average speed = 75 km/h

(E): fewer accidents --> should be implemented; affirms the sufficient (speed limit = average speed)

C: speed limit = 75 km/h

Note that (E) still requires a huge assumption that the govt believes that the measures put forward by the study will work; but so does (B).

tldr; experiment design framework (my take). The conclusion essentially states that something's wrong with the design of the experiment. Therefore, answers that fix the experiment will weaken the conclusion, and answers that spell out the flaw will strengthen the conclusion.

The premises state that there are two things that hard to control for: concentration of killer molecules in the bag and effective concentration (proportion of killer molecules in the soil).

(C) pretends to strengthen the experiment by saying that we don't need need to control for one of the two variables (molecule breakdown in the soil)

(D) pretends to strengthen the experiment by controlling for one of the two variables (molecule breakdown in the soil)

(E) pretends to weaken by asserting that only one of the two molecule forms was analyzed

(A) pretends to control for the difference between the molecule forms by reiterating the information from the stimulus

(B) weakens the argument by showing that the experiment controls neither for the concentration in the bag nor for the concentration in the soil.

It feels like somewhat casual explanations didn't do justice to this question. (B) seems to be baiting for sufficiency-necessity confusion which could work on those who's assumed that hiccups is necessary for Ebola.

The stimulus however counterintuitively stipulates that Ebola is necessary for hiccups ("a symptom of no known disease except"). The stimulus also states that Ebola causes hiccups in many victims. The two stipulations illustrate a rather surprising fact that causal and conditional relationships can flow in the opposite (!) directions between the two phenomena:

hiccups --> Ebola

Ebola --c--> hiccups (in most victims)

(B) stipulates that

Ebola --some--> /hiccups

There is no way to come up with this breakdown under time pressure, but it's worth getting to the bottom of it on a blind review.

I don't see any issues with the question. Here's my proof that all vacuum tubes are not in fact preferable, regardless of heat resistance.

i) Let's take the whole superset of vacuum tubes; ii) Let's take ANY one and assume that it's preferable (for whatever reason, known or unknown to us); iii) two things follow: a. this tube's maximum current capacity is not comparable (because every vacuum tube has this property) b. this tube is comparable to semiconductors in all significant respects, such as maximum current capacity (because all preferable components must satisfy that necessary condition); iv) a. and b. contradict each other, therefore our initial assumption that the tube is preferable was wrong, therefore it is NOT preferable v) we picked a random (ANY) vacuum tube at the beginning, so the conclusion applies to every one in the superset (we can repeat this sequence of reasoning for every vacuum tube in the set).

In plain English: there are no preferable vacuum tubes in the superset, because any preferable would fail the necessary condition of being comparable to semiconductors on maximum current capacity.

tldr; the claims in the premises are so strong, they govern things that we are not explicitly said.

tl;dr: no contrapositives for "most"'

Google's Gemini has supplied a perfect illustration:

- The Premise (True): Most iPhones are black.

- The Inference: "If a phone is not black, it is probably not an iPhone."

If you walk into an Apple store and look at all the phones  that are not black, what are they? They are all iPhones. The probability that a non-black phone in that store is "not an iPhone" is 0%.

The video makes a great point on (E) which is somehow absent in the text version: "We know that all antibiotics now on the market, a vast subset of antibiotics, don’t fall within the exception, which means they have to follow the rule. What antibiotic are we talking about here?" (E) evades the rule through remarkably subtle language: "antibiotics that have been used."

Very educational dissection, thank you. Couple of observations: 1/ this long sentence appears to have lost its verb along the way: "Just because we now know that storytelling appears to be a universal aspect of culture and language does not the storytellers themselves have known it all along, especially not those from distant epochs." 2/ it may be worth highlighting that "all of the world’s cultures" in (C) seems to directly correspond to "a universal aspect of both past and present cultures" in the stimulus (all of the world’s literally means universal).

@JackVassau "[things that] should be provided, then..." is the necessary condition for the "things necessary for human health", not for the "primary purpose" condition. Just like B is not a necessary condition for C in A -> B -> C. Note that it reads if A, then if (!) B, then C.

When we kick "things necessary for human health" up to the domain, "then" before "[things that] should be provided" is removed along with the starting "if", just like "then" will be removed before B if we kick A up into the domain and are left with B -> C (if B, then C).

"So such wounds is a reference to deep wounds free of bacteria." (0:50 mark in the video) is a false statement. "Such wounds" refers to "deep wounds".

If we swap out the referential in the second sentence by the referent as suggested in the video, the resulting sentence will make no sense: "Even strong antibiotics failed to kill the bacteria that live in deep wounds free of bacteria."