When applying the negation test, does it mean that negating the correct answer choice would render the conclusion impossible, or just that the premises would no longer support the conclusion? It makes more sense to me that it would mean that the negation of the answer choice would mean that the conclusion can absolutely no longer be drawn, but there's a few questions in the upcoming lessons where it seems like that isn't the case. Instead, it seems like if the correct answer choice weren't true, that the premises just no longer directly support the conclusion. However, negating the answer choice doesn't seem to preclude the possibility of other assumptions being made that could allow the conclusion to be drawn.

Take this with a grain of salt, but after a lot of thought, I think I was able to articulate to myself the reasoning for E being the correct answer (with the video's help of course):

If Wally’s is a large nursery, then what do we know to be true? We know that Wally’s probably (because of the “most” statements regarding large nurseries), sells primarily to commercial growers. And we know that Wally’s probably sells plants that are guaranteed to be disease-free. But how can this be? Maybe Wally’s is not part of the “most” nurseries that guarantee this. But that’s not probably what happened. (It is possible, because it’s not ruled out by the lawgic. But is that strongly supported by the stimulus? No. That’s actually less likely to be true because according to the stimulus, and given that Wally’s is a large nursery according to E, Wally’s most likely does have that guarantee.) Because most large nurseries have that guarantee, then Wally’s probably did have that guarantee (because according to E, we’re saying that Wally’s is a large nursery). So Wally’s probably had that guarantee. How can this be true? Well, Wally’s probably had that guarantee, but the guarantee probably failed. The raspberries were not actually as they were guaranteed to be.

Someone please help lol. After writing out "endorsement → [certain conditions]," JY says "[James] did something to make this conditional endorsement to go away. And what's the thing he could have done? The only thing he could have done?" And then says that James must have failed the necessary condition. But isn't it true that failing the necessary condition is not the only way to come to the conclusion of /endorsement? The contrapositive gives us /[certain conditions] → /endorsement. So fulfilling the /[certain conditions] sufficient condition is sufficient to come to the conclusion of /endorsement, but I thought we learned that just because there isn't a conditional statement, it doesn't mean that there are not other routes that can be taken to get to necessary condition. I.e., just because A → B doesn't mean that X → B can't also be true. So as it relates to this question, I don't see how answer choice E is necessary. I see how it's sufficient to make the argument valid and brings you to the conclusion of /endorsement, but aren't there other avenues that also could have been taken to get to the conclusion of /endorsement? For instance, can't it be true that maybe the proposal that the chair had seen actually did include all of the recommendations (meaning E is false), but the chair still decided not to endorse for another reason? Like maybe she was just in a bad mood that day? The argument doesn't seem to exclude this possibility. It only looks like it would exclude this possibility if the conditional had been "if and only if" rather than just "if."

I would really appreciate some help!! I'm really struggling to see how this is a necessary assumption and not just a sufficient assumption. Thank you!!

In the explanation for choice C, it's mentioned that our chain tells us that "fish and /birds → gerbils." Therefore, we can infer that some stores that sell gerbils also sell fish but not birds (because an "all" statement in one direction implies a "some" statement in the other direction, or really both directions, because that's how "some" works).

I vaguely remember learning this in a foundations lesson, but now I'm wondering, what if there are no "fish and /birds" stores? Like, what if all the stores that sell fish but not birds closed down? We could still say that "if a store sells fish but not birds, it does sell gerbils," because that is given to us in the stimulus, and the validity isn't affected by anything. In a world where all of the stores that sell fish but not birds closed down, "fish and /birds → gerbils" could still be valid, but there just wouldn't be any of those particular stores to fulfill that rule.

But now, in that world, can we still say that "some stores that sell gerbils also sell fish but not birds"? Probably not, because we could have stores that sell gerbils, but all the stores that sell fish but not birds closed down. So none of the stores that sell gerbils also sell fish but not birds.

I understand the logic behind inferring a "some" statement from an "all" statement, but can't get over this one possibility. The only answer I can come up with is if the very presence of something as a sufficient condition in a conditional relationship implies the existence of that thing (i.e. "fish and /birds → gerbils" indicates that there are existing stores that sell fish but not birds.) Or I'm wondering if maybe this is only the case for "all" statements, but not "if, then" statements? Because with "if, then" statements, the very basis of the relationship is that "if" something is true, "then" another thing is true, which kind of opens the door for that sufficient condition to maybe not be true in some scenarios (right?). Like if we reworded our original premise to "if a store sells fish but not birds, then it sells gerbils." Well, what if a store doesn't sell fish but not birds. What if none of the stores sell fish and not birds? The rule could still exist in this world, but we're just waiting for a store to open up that actually fulfills it.

Or maybe I'm just way off in some other way. If anyone knows what I'm missing here, I'd really appreciate your help!

After a LOT of thought, I think I came up with a good explanation for why AC A is the correct answer for Question 15:

The final paragraph seems to have a sub-conclusion and a main conclusion: The sub-conclusion is the line that says "Hence creating a link to a document is not the same as making or distributing a copy of that document" (line 42). This lends support to the main conclusion in the last sentence: "Changing copyright law to benefit owners of intellectual property is thus ill-advised" (line 52).

At first glance, it looks like AC A really just captures the idea presented in the sub-conclusion: that creating a link to a document does not take away any control of distribution from the author, and therefore creating such a link is not considered copyright infringement.

But wait, that's not what A says. It doesn't say that, therefore, "creating such a link is not considered copyright infringement." It says that "creating such a link should not be considered copyright infringement."

It looks like, then, this second part of AC A actually does capture the meaning (albeit somewhat implicitly) of the main conclusion presented in the passage's very last sentence. The passage states that "changing copyright law to benefit owners of intellectual property is thus ill-advised." In saying "creating such a link should not be considered copyright infringement," AC A is saying that the copyright laws should not be altered to extend to the prohibition of the creation of links to documents. It can be viewed as saying that "creating such a link should not be considered copyright infringement by new/changed laws."

AC A essentially uses the descriptive sub-conclusion (starting with "since") to support its prescriptive main conclusion (starting with "creating"), which is exactly what the last paragraph did.

I feel kind of silly not just recognizing this as a "rule/exception to the rule" conditional type argument, but I did get the right answer and then in the blind review used lawgic to check the validity.

Using the indicator word "unless" to negate the sufficient, I got "if an antibiotic doesn't eliminate the species, the species becomes more resistant within a few years"

/eliminate → resistance

and with its contrapositive (just for funsies):

/resistance → eliminate

Then using the indicator word "no" in the second sentence, I got "if an antibiotic is currently on the market, it cannot eliminate species X"

current → /eliminate

contrapositive:

eliminate → current

Now if we connect some of these, we get:

current → /eliminate → resistance

Which is exactly what B says (current → resistance).

I feel like I'm not consciously doing this whole thing when I'm under the time constraint, so I'm not sure if I'm just lucking out or if I just know deep down in my heart of hearts what to do lol

For Question 5, it seems like kicking up to the domain changes the meaning of the original claim.

"If something is necessary for human health, then it should be provided by an organization whose primary purpose is the promotion of health."

nec-human-health → should-provide-org-ppph

vs.

Domain: things necessary for human health

should provide → org-ppph

/org-ppph → /should provide

Without any context surrounding the claim, it looks like the author is arguing that "if (thing) is necessary, then an org-ppphs should provide it." This is not saying that other types of organizations should not provide that thing. Rather, that it is a responsibility of the org-ppphs to (i.e., they "should") provide it. Translating to "should-provide → org-ppph.... /org-ppph →/should provide" seems to only actually track if the original claim had stated that the necessary things should be provided only by org-ppphs. Basically, I interpreted the word "should" as implying a duty of org-ppphs, rather than interpreting it as meaning something exclusive to org-ppphs.

However, this may be different with context. If the previous sentence said something like "only org-ppph are capable of providing the necessary things," then it would naturally follow that organizations that are not org-ppph should not provide those things. Otherwise, it seems like the reasoning behind the original sentence means something more like "org-ppphs are capable of providing the necessary thing, and therefore they have a responsibility to provide it." (Also, I'm not trying to make unnecessary assumptions here where they're not given. Just trying to show that context seems like it could change the meaning of the word "should," and a complete lack of context seems to leave some holes.

I think without knowing what the author is arguing or any surrounding context, it doesn't make sense to assign "should" a different meaning than what was originally written. Or perhaps the sentence is originally somewhat ambiguous, which paves the way for inaccurate interpretation.

So is this technically a PSAr question or a Principle question? It came up in my drill for PSA questions, but the lack of the word "justify" makes it seem like it's a Principle question, which I haven't even gotten to yet in the syllabus.

#feedback I think there's a typo in the written explanation for answer choice E: "the stimulus already foreclosed the hypothesis that Travaillier's current customers' preferences have changed." Should that instead be "have not changed"?

The explanation for choice A states that "The argument never mentions individuals who claim they experience acne outbreaks during high-chocolate periods." But the sentence in the stimulus right before the conclusion says, "many people who are susceptible to acne report that, in their own experience, eating large amounts of chocolate is invariably followed by an outbreak of that skin condition." How is this not mentioning individuals who claim they experience acne breakouts during high-chocolate periods"?

Sorry if this has been answered before, but for logical reasoning questions, should we read the question first before the stimulus so we know what to look for? Or just read the stimulus first?