@Kevin Lin yes, a Fast Track - Negation video would be super helpful! Especially where negation leads to double negatives; how we can read them in a way that makes more sense.

Such a helpful explainer with great take-away tips; thank you Kevin!

One question: in Question 4 re: macaque monkeys, you mentioned that B is easy to negate because you can just take away the "not" in a sentence that is "Subject is not Predicate", ie negated AC becomes "Subject is Predicate".

Is it it always okay to do that, or are there some parameters around when we can do that? (for example, if the Subject is singular not plural)?

Or are there cases where just dropping the "not" may not work how we need it to for a negation test? Ie, where taking a way the "not" needs to be a "some" instead of "all" relationship? ie, "Subject is not Predicate" needs to be negated to "Subject is SOMETIMES Predicate" or "Some Subject(s) are Predicate" to properly evaluate whether it breaks the argument?

@dbershadskaya801 Great explanation with walk through of the whole thought process! One small note thought: the negation of "know a lot → /freely performed" is not "know a lot → freely performed", but rather "know a lot <--s--> freely performed". The negation you used worked out in this answer choice, but I wonder if it could be problematic in another question?

@Robert Carlson Thanks for this explanation and linking back to the Negating Conditional Statements lesson.

I found JY's lesson understandable once we translated "Not (KLE --> /FP)" to "KLE and FP" but was confused how we got to KLE and FP. Negating a conditional yields a some statement, ie "Not (A --> B)" is "A <--s--> /B". This is noted in your text “we know at least there are some situations out there”.

Questions:

1) How do we get from “A <--s--> B” to “A and B”?

a) Is “A and B” just saying that this combination is possible?

b) Under what circumstances are “A <--s--> B” to “A and B” equivalent, or not equivalent logical statements?

2)  Since A <--s--> B is a some statement, how can this be used for a “Two Split Most” or “Two Split All” conditional?

3) The some statement would yield J --> KLE <--s--> FP. How can we draw inferences from an All before Some statement?

#feedback: the Fact v. Belief v. Knowledge link is broken

I struggled with this one and was unsure why B and D would not be right. I understand now it is about clearly identifying the subject that the adjective "peevish" applies to: Allen's depictions, not the artists depicted.

#feedback: The explanation for AC (B) is nested under AC (A)

Also the diagrams in JY's video would be helpful in the summary and ACs!

I appreciated Kevin's video explanation to understand why Confidence matters in this situation, though it seems to be outside knowledge. I would have thought that the premise that Confidence is NOT correlated to Accuracy, together with a reasonable assumption that Accuracy is what really matters in identifying a suspect, would imply that Confidence doesn't matter. So I looked for answer choices that focus on Accuracy.

I recall in the Core Curriculum that some premises can be extra fluff for distraction and are not used in support of the Conclusion. I assumed that the second sentence, [Factors can affect confidence without altering accuracy] to be an "extra fluff" extension of P1.

How can we tell the difference between a "extra fluff" sentence and a key premise on which the argument relies?

@Jsonf This is awesome. I had chosen D and then watched J.Y.'s video and my takeaway was "who cares". This emphasis on the love of 6 pets helped to solidify why D is irrelevant.

I was hoping for an update in the discussion about the horses

It doesn't change the conclusion of the court, or our general understanding of this passage, but just FYI, I think the reference to "prevented, by circumstances beyond their control, from exercising a tradition for a given period of time" refers not (only) to the 1910 treaty, but also since the occupation of the territory by Russia in the late 1700s. It is quite possible that there were still elders in 1991 who could recall those practices before 1910. However, for sure, practices before the late 1700s would not be within "living" memory but nonetheless passed down through oral histories or other means. Traditions (likely over hundreds or thousands of years) that were commonly practices but disrupted by the circumstances of Russian occupation (for 200 years) should still be considered by common sense as "traditional".  (I work in this field). 

@allyldh I agree - I thought it was too easy to pick A just by reading the questions stem and answer choices; the others didn't seem to make sense at all when the question stem just describes access. Then I looked carefully through the passage again to see if there was something more directly connected to any of the ACs and came up blank. I was wondering if I was missing something in how to approach the question until the explanation video/text essentially says to eliminate any ACs that require an unsupported inference.

I chose B because I read "zoologists classified" in the past tense, as referring to the classification as horses, and I thought the now-accurate classification and "rightful place" as as giraffes was the author's opinion, not zoologists. But that missed recognizing that "further studies showed" implies that zoologists did this and correctly classified them as giraffes, some time in the past.

Also, I now realize that the question stem is not asking us to identify any inaccurate statements, but rather not-explained statements.

Like some of the older comments/questions about correct AC (E), I had also thought "choosing to move on and sample other leaves" was an explanation. But now knowing that it is the correct AC, I can see how that phrase can be read more of an expansion/detail about the way that okapis leave preferred foliage uneaten, rather than an explanation for why.

Super appreciate the pro tips!

I did not see that myself, but I think you are right? Unless the wording is some kind of bi-conditional that I am not understanding!

In my shallow dip, I saw C was logically equivalent was 100% confident about it, and moved on.

But I see now how the ACs can be tricky... E is "more similar" in reasoning structure than C. So for the future, we still need to dip all the answers...

I  got this right quickly but I think only because it followed right after the previous question. If I wasn't already looking for the same concept, I may have been flip-flopping with D, and unsure of when to take a charitable interpretation of an author's premise, and when it would be strawmanning. Here, it seems to me to be a reasonable weakness (it's true that it's an assumption), so it didn't seem "over the top" strawmanning. 

I think for future, I would think, ok, even if the author DID strawman the argument a bit, that still leaves a major flaw of having not proven his own argument of NOT the case that [making govt changes --c--> eliminate social ills]. 

#feedback, I think "daily" in the summary of Answer Choice D should be "duly"

For E, I think the uncertainty about whether the scientists had the right assumptions for their hypothesis to link vision and hearing shows that the evidence was not irrelevant to the conclusion. It might not be the right conclusion to come to from the evidence, but the evidence was at least relevant to the hypothesis. 

@soohae.c I was also confused, because when we did weakening questions, we talked about alternative hypotheses as weaknesses. But The way I understand it here:

FLAWS are about a formal error in the structure of the argument itself. Here, the error is that the causal logic structure of (Eliminate lead paint --c--> eradicate child lead poisoning) would fail if there are other sources of lead that also have a causal relationship. Ie, there are multiple --c--> arrows pointing to child lead poisoning, and scrubbing out one cause does not mean the others aren't still there.

WEAKNESS is about the way that an argument is undermined. In E, we are still using the same causal logic given in the stimulus (Eliminate lead paint --c--> eradicate child lead poisoning), but pointing out some assumptions that are needed to fulfill the sufficient assumption to make that given causal relationship run through.

I also don't know if this distinction applies to all flaw questions, but that is how I understand this one!

I think it means it is a fact that would be triggered "if" hypothetical condition was met. The editorial argues that the "if" condition may never be met, but the except is still a fact that the editorial grants is true.

@NobitaNobi

1. Persuading them to relocate is not sufficient but it is necessary. If you can't persuade them to relocate, for sure you can't hire them or keep them.

2. I think we have to take the premises as true. ie, if the rule is "reducing class sizes requires hiring more teachers", then we can't think about other options for reducing class sizes. Also the conclusion is still about the link between reducing class sizes and overall student achievement (not more qualified teachers and student achievement).

@JackCheston I had the same thought about Answer Choice C, but then realized I was thinking about Sufficient Assumptions.

C does reasonably imply a time scale - not in the first month electricity bill, but over the long term, the cost savings must at least cover the cost of the initial investment (purchase/installation). That is necessary; if the reduced monthly electricity bill differences could never add up to cover the initial generator investment costs (e.g. if the generators have a lifespan that does not allow costs to be recovered through savings), then the conclusion of overall saving money could never be realized.

Answer Choice C is not in itself sufficient - for that, there also must be a necessary assumption that the costs of ongoing operation and the maintenance of the generators still generate electricity bill savings to allow the initial investments to be paid off. But that would be Sufficient Assumption territory. 

The grammar parsing was super hard. I only understand the comparative claim after reading/watching the video.

But now I understand that: if [the DNA of prehistoric Homo Sapien ancestors was NOT significantly more similar to Neanderthals than is the DNA of contemporary humans], it would mean that the fact premise [the DNA of contemporary humans being significantly different than that of the Neanderthal] would not necessarily support the conclusion that they didn't interbreed. That fact could be the result of genetic change over time after interbreeding.

My right answer was flagged for blind review too... but it took me 5 minutes to get to the right answer, so I think that was fair!