Remember, pointing out a flaw in the argument involves showing why the author's premises don't prove the author's conclusion. We do not have to prove that the author's conclusion is false.

You are correct in suggesting that if there were some other kind of compound that was neither synthetic nor non-synthetic that could be the true cause of the rise in cancer rate, it could still make sense to believe that the rise in cancer rate is not caused by synthetic compounds.

However, you're ignoring the fact that the author of the argument gave us a particular premise that they believe proves that synthetic compounds are not the cause. What is the premise? That the # of nonsynthetic compounds is higher than the # of synthetic compounds. The author believes that that premise -- and that premise, by itself -- proves the conclusion. By pointing out that level of exposure is a factor that matters, not just the comparative # of compounds, we have shown that the author's premise isn't enough to lead to their conclusion.

You're onto something, but this is only part of the issue. The only reason that you're trying to make the necessary condition of the premise the sufficient condition of the assumption is that the conclusion brings up the new idea of " more frequent economic crisis" on the necessary side. If the conclusion had brought up a new concept on its sufficient side, then we'd actually be looking for something different.

For example:

Small elite -> info that determines welfare

Conclusion: Countries on tropical islands -> info that determines welfare

Here, the SA would be "Countries on tropical islands -> small elite". Do you see how the rule you were describing -- that we generally want to make the necessary of the premise the sufficient condition of the assumption -- doesn't work here?

Can you explain this a bit further? When you say that E seems like the conclusion stated in different terms, are you saying that you think these two mean the same thing?

"A society would not willingly accept a system where electronic transactions are recorded."

"No government can operate an economy without the use of paper money."

Notice how the first sentence is about what society would not accept.

The second sentence doesn't say anything about what society would accept. It's instead about what the government can do. So in that sense, how does the second sentence say the same thing as the first?

Are you thinking that if society doesn't accept the system, then that would mean the government can't use that system? If so, there are 2 points you should consider:

First, the main conclusion of an argument is different from an idea that is implied by the main conclusion. So even if it were true that society not accepting something implies that the government can't do the thing, that doesn't make "government can't do the thing" the same idea as "society won't accept the thing".

Second, society not accepting something actually doesn't imply that the government can't do it. Why couldn't the government implement a system that people don't willingly accept? The government can just execute people who try to openly rebel or agitate for a different system. The government can force people to use that system. So (E) is actually not even something the author needs to agree with.

"Medical care should be provided by a trained professional."

Is that saying that every trained professional should provide medical care?

"The most dangerous stunts should be performed by the stuntmen and stuntwomen we hired."

Is this saying that every stunt(wo)man should perform the most dangerous stunts?

"Mundane tasks should be done by an intern."

Is this saying that every intern should do mundane tasks?

It might help you understand #19 if you added an implicit "only" after between "provided" and "by". "X should be provided only by Y" = If X is provided, it should be Y that provides it.

Never get rid of an answer merely because you don't understand what it's saying. Only get rid of answers because there's something specific about them that you believe makes it wrong.

Your goal is to pick an answer that accurately describes the role of the statement in question. Whether something is broader or more specific is not a factor that should guide your decision.

The "broader" aspect of (A) I think you're referring to is the part where it says "... conclusion that people have a positive or negative response to any word". The only question you should have if stuck on (A) is this: Was that the conclusion of the argument? Did the conclusion really say that people have a positive or negative response to any word? If the answer is no, then this answer is wrong.

In this particular problem, (A)'s description of the conclusion happens to be broader than what the conclusion actually said. But the takeaway isn't "We prefer specific over broad." The takeaway should be when an answer tries to describe the conclusion of the argument, make sure it actually gets the conclusion right. A different problem might have a very broad conclusion, and in that case, it's OK for an answer to describe the conclusion broadly, as long as it's accurate.

Make sure to break arguments down into conclusions and premises. It's not helpful to refer to "statements" -- it can make a big difference whether the statement you're refer to is a premise or whether it's a conclusion. In this case, the statement you're referring to -- that there's no evidence coffee harms the heart --- is a premise. It's a reason offered by the author in support of the conclusion. What's the conclusion? That coffee is safe to drink.

Does showing that there's no reason to think coffee harms the heart prove that coffee is safe to drink? To weaken this argument, we want to show that coffee might NOT be safe to drink even if it doesn't hurt the heart.

The correct answer points out that coffee MIGHT hurt overall health, which would be a reason it's not safe. The argument jumped from safe for heart to safe for health, when they're not the same thing. What if coffee gives you dementia? What if coffee hurts your kidneys? What (B) does is show that the author's premise -- that coffee doesn't hurt the heart -- does not by itself prove that coffee is safe. That's why it weakens. We're bringing in overall health because when you say that something is "safe", overall health is relevant to the idea of safety. Consider this:

Eating a lot of greasy foods doesn't hurt my fingers.

So, eating a lot of greasy foods is safe.

Wouldn't it weaken this argument if you pointed out that there's more to being "safe" than whether something hurts your fingers? What if we got an answer that says "Not hurting your fingers isn't the same as not hurting your overall health." Would you still be asking why overall health is relevant to this argument?

For (C) - keep in mind the conclusion: coffee is safe. Does (C) suggest any reason why drinking coffee might hurt the heart? Be precise here. Yes, I know that (C) is trying to suggest that coffee drinkers will eat other stuff with their coffee that hurts the heart. But does pointing out that eating a donut hurts the heart have anything to do with whether coffee hurts the heart? Yes, I know that (C) is trying to suggest that eating a donut and drinking coffee often go together. But again, does saying that the donut hurts the heart have anything to do with whether coffee hurts the heart? Not exactly. The only way that the point (C) is trying to make would weaken the argument is if coffee drinking causes one to eat the other bad foods. If so, then that's how drinking coffee might not be safe, even if it doesn't hurt the heart. But there's nothing in (C) that is suggesting that the coffee is causing anyone to eat the other bad foods. They just happen together.

Consider the example argument from earlier:

Eating a lot of greasy foods doesn't hurt my fingers.

So, eating a lot of greasy foods is safe.

Would this weaken the argument: "But a lot of people who eat greasy foods also drink beer while they're eating those foods, and beer is unsafe." No, because the conclusion is about greasy foods being safe -- pointing out that another thing that happens to be consumed along with greasy foods is unsafe doesn't affect whether greasy foods are safe, unless we can say that the greasy foods are causing people to drink the beer. (Which we can't.)

I might have a slightly different take on this argument compared to other explanations.

First let's break this down.

Premise 1:

Involuntary action -> Clear sign of chemical control.

Premise 2:

Humans have free will.

Intermediate conclusion:

Psychological factors have taken over.

Main conclusion

Pheromones are useless.

Let's follow the author's reasoning. First, the reason the author is relying on the fact that involuntary action in animals means chemical control, is that the author is mixing up the sufficient condition and necessary condition. The author thinks that Premise 1 implies "Voluntary action -> NOT chemical control." So this is the first assumption the author makes, which happens to be what the correct answer identifies. (Assumption #1)

But that's not the end of the reasoning. The author then tells us that humans have free will (voluntary action) -- in the eyes of the author, this triggers the mistaken conditional "Voluntary action -> NOT chemical control". So at this point, the author believes he has established that sexual behavior is NOT based on chemical control (because it is voluntary action).

The next step in the author's reasoning is the assumption that if something is NOT based on chemical control, then that means psychological factors have "taken over". (Assumption #2)

Then the author jumps from the claim that psychological factors have "taken over" to saying that pheromones are useless. (Assumption #3)

Assumption #2 ("If something is NOT based on chemical control -> Psychological factors have taken over) looks very similar to answer choice (A), which is why it's so tempting. I would get rid of this answer because the word "purely" is not required to be assumed. The conclusion was just that psychological factors have "taken over", not that the explanation for sexual behavior was "purely psychological".

The author's intermediate and main conclusions allow for there to be some explanatory factors that are not psychological (as long as they're not chemical). The conclusion is really just saying that sexual behavior is predominantly psychological and not chemical; however, the rest of the explanation of sexual behavior might be something besides psychological factors or chemical factors. I'm not sure what those factors would be, but no one ever established that psychological and chemical are the only 2 possible explanations, nor is that some definitive fact about the the world that the LSAT is assuming is true. Perhaps there is some other biological factor compelling people's sexual behavior that isn't chemical in nature? Genetics might cause people to be attracted to height, healthiness, and other factors, and that contributes to people's sexual behavior -- does genetics have to work through chemicals? No.

So, to recap, the author made 3 bad reasoning moves:

1: Voluntary action -> NOT chemical control

2: NOT chemical control -> Psychological factors take over [which doesn't mean "purely" psychological]

3: Psychological factors take over -> NO chemical explanation (or in other words, pheromones are useless)

(B) is 1. (A) tries to describe 2, but is too extreme with "purely".

----

I would be careful about getting rid of (A) because of "whatever". (B) itself could have used that word: "Whatever is a voluntary action cannot have a chemical explanation." That could still be the correct answer.

The lesson says that "Some unicorns don't poop rainbows" is a "tempting but incorrect negation". The correct negation is identified as "No unicorns poop rainbows", which is the same as "None of the unicorns poop rainbows."

You might find this post I made on weakening helpful: https://classic.7sage.com/discussion/#/discussion/33134/some-pointers-on-weakening-you-can-weaken-by-showing-inconsistency

It should address one of the issues you might be having with this problem.

I think the issue here is that we're being too mechanical in our diagram.

In the abstract, "A is B" can be seen as A -> B.

However, depending on the content of "A" and "B", it might also be appropriate to think of "A is B" as a biconditional "A B".

"The fastest runner is the best runner."

This does mean that Fastest runner -> Best runner. But doesn't it also mean Best runner -> Fastest runner? Yes, because there's only one "fastest" and only one "best". So whoever is the fastest is the best, and whoever is the best is the fastest. It doesn't make sense to say that someone can be the best but not the fastest, because if X, for example, were the best but not the fastest, then that means another person would be the fastest...but then that person would be the best, instead of X, and we end in a contradiction. So fastest and best are the same person because of the meaning of "-est".

"The people whose lives we'd most like to live are those whose characteristics we admire most."

Do you see the parallel? "Ppl whose lives we'd most like to live". There's only one such group of people out there, because of the word "most". Whoever is part of that group are the "people whose characteristics we admire most". So Most like to live -> Characteristics we admire most.

But this also means Characteristics we admire most -> Most like to live. How do we know this? Because would it make any sense for there to be a group of people, let's say X, who's characterics we admire most, but for that group to not be the people whose lives we'd like to live the most? If that's the case, then there would be a different group of people whose lives we like to live the most, which would then mean we would admire that group's characteristics the most...but that contradicts the idea that X is the group whose characteristics we admire most.

Does that make sense? You can't just take "A is B" and turn that into A -> B for every single statement; the actual meaning of the concepts does play a role in how we interpret the statements.

"Joe Biden is the president of the USA."

Of course that means JB -> Pres, but that also means Pres -> JB, because there's only one president.

"Joe Biden is a very old person." This means JB -> Very old, but this does not mean that Very old -> JB because there's more than one very old person in the world.

Actually there's a subtle difference between (B) and (D) that might allow you to pick (D) without resorting as much to the idea that pollution is more reasonably connected to cancer than wealth.

Notice that (D) says that countries with high fat are also the countries with "the highest levels of environmental pollution." So this answer establishes a correlation between fat and pollution. The high fat countries are the highest in pollution. The low fat countries are not the highest in pollution.

However, compared that to (B). (B) says that the countries with high fat "tend to be among the wealthiest" in the world. Do you see how this doesn't preclude the low fat countries from also being among the wealthiest in the world? In fact, it's entirely possible that the wealthiest countries in the world are dominated by lowest fat countries. It's just that there's also many high fat countries among the wealthiest, too. (B) does not actually establish a correlation between wealth and high fat. This is why you can get rid of (B) and pick (D) without resorting as much to the idea of more reasonable or less reasonable assumptions.

This would be a good answer if we knew that the countries with higher fat tended to have more of food X than the countries with lower fat. But the answer doesn't suggest that. In your example, you note that what if one country has all pasta v. all fish? But does the pasta-fat correlation hold on average for other countries that are high in fat? We don't know. One country is fat b/c of pasta, another country could be fat b/c of steak, another country could be fat b/c of bacon. And another country could be low fat because of sushi, another because of carrot smoothies. This situation doesn't hurt the argument unless we know that the kinds of food eaten by the fat countries has something in them that's cancer causing that the kinds of food eaten by the low-fat countries don't have.

Simply pointing to another factor that's involved in potential cancer rates doesn't hurt the argument unless we have some reason to believe that that factor differentiates the high fat countries from the low fat countries.

Neanderthals can stay in the same place and kill whatever animals show up - some of those animals may be moving around and some of them might stay in one place.

Of course, it's possible that Neanderthals follow the migratory animals around. But that's not suggested by the answer choice. Think about it this way: Modern humans eat a variety of migratory (birds) and non-migratory animals (pigs). Does that in any way suggest that modern humans are nomadic?

The negative consequences are the "accidents". Notice that "accidents" is in quotation marks because the speaker is suggesting they are not really accidents. Amar is suggesting that commercial fishing boats would intentionally catch fish they're not supposed to and then say it was an "accident" in order to keep the fish as Sarah proposes. This is the negative consequence - people catching fish they're not supposed to and getting away with it.

This is an interesting resolution and does make sense. Your explanation shows how answer choice (C) would not contradict the stimulus, even if we interpreted the second sentence as saying that overall, the people in toning shoes don't walk more than the people in regular shoes.

I think the second sentence is supposed to mean that the toning shoes themselves do not exercise the muscles more through their design - like, they're still just regular shoes and there's nothing special about them as far as major leg muscle exercise goes. But, I can see how the second sentence could be ambiguous - maybe it does mean that on average, the actual people who use toning shoes don't get more exercise for their major leg muscles. In that case, your explanation would still allow (C) to make sense.

Another way to make sense of (C), even if the second sentence refers to actual people who use toning shoes is just to interpret the second sentence as about an average. On average, people who use toning shoes don't get more exercise. That still allows "many" people to experience an increase in exercise after switching to toning shoes, however.

It's absolutely possible to do this quickly as you get more experience. If you're just beginning with diagramming, try not to compare yourself to the timing standards of a master. Ultimately, by the time of the test, you'll have done so many problems that are just like this one that you'll be much faster.

Are you sure that (E) is referring to social darwinism when it says "scientific theory"? My reading of it is that the scientific theory is the theory of evolution. And under that reading, Gilman did not have her own version of the theory of evolution. She had a version of a sociological theory that was influenced by the scientific theory of evolution. Does that make sense?

Notice that this understanding fits with B, since the scientific theory B refers to is the theory of evolution. Part of the consequences of the theory of evolution was Social Darwinism, and the passage is about Gilman's role in the debate over Social Darwinism.

This isn't very well known, but one of the LSAT's lead writers was an unfrozen caveman who joined the LSAC following a distinguished career as a lawyer. (https://youtu.be/2AzAFqrxfeY)

This not only explains the numerous ice age problems, but also the many problems about controlled fire and dinosaurs.

Remember what it takes for something to be the main conclusion:

1. The author must provide a reason for why it's true, AND

2. The author does not use it to help prove a different claim.

The word "but" is a helpful indicator of where the author's argument is likely to begin, and it often does come right before the conclusion, but it's never the reason something is a conclusion. So you might be wrongly thinking of "but" as having some rule-like significance. It doesn't - in any other problem where JY or someone else points out the but and relates it to a main conclusion, the "but" has nothing to do with what makes it the conclusion. It's just a sign saying "You might want to think about this - could it be the conclusion?"

So let's apply the critieria to "Not the first shred of evidence of life has been forthcoming." I'll translate that to "We don't have any evidence of life so far."

Is there any line that the author uses to help prove that we don't have any evidence of life so far? I don't see any. There's nothing to show how it is that we know there's no evidence. The author merely asserts that this is true without any proof of it. (I assume that what's happening is that we haven't found any responses in the skies from our scanning, and that this is the reason the author thinks we have no evidence. But the author never says "We haven't found any signals or responses from our scanning. So there's no evidence of life." What you might assume is motivating the author's claim is not the same as a stated premise in support of the claim.)

This is enough to make the line not a conclusion.

The quickest way to get rid of (C) is to realize that there's a difference between saying "there's no reason to believe the theory" and "the theory is incorrect". The argument never actually says that the other theory is wrong; it just says there's no reason to believe it. So a principle about a hypothesis being correct is just about a different concept.

Saying that there is no reason to believe aliens exist is not the same thing as saying aliens do not exist. Saying that there is no reason to believe that I'll win the lottery is not the same as saying I won't win the lottery.

For a more complete explanation:

(C) is a conditional statement that says

If a hypothesis accounts for something AND that thing is not adequately accounted for by another theory -> then that hypothesis is likely to be correct.

There are at least 2 big problems with this answer as a necessary assumption.

First, did the author conclude that a hypothesis is correct? Not really - the conclusion is just that there is no reason to believe that the "light-absorbing" hypothesis is correct. So a principle that's about what leads to a hypothesis being correct (like (C)) isn't relevant to an argument that's trying to prove something has no evidence of being correct. We would have needed an answer that ends with "...-> then there is no evidence that the hypothesis is correct."

Second, consider the "If" part of the answer choice. Does that match up with the reasoning of the argument? The argument is saying that general relativity already accounts for the low visibility. But it doesn't say that the "light-absorbing" hypothesis does not account for the low visibility. The argument's reasoning is that, regardless of whether the "light-absorbing" hypothesis accounts for low visibility, there's another theory that already explains it. "Regardless of whether X explains it" is not the same as saying "X does not explain it."

(Note: If there's any chance you're tempted by C because you're thinking that the hypothesis that it's referring to is general relativity, then make sure to identify the conclusion properly. The author isn't trying to prove that general relativity is correct. They just said that it explains the low visibility phenomenon, and this is being used as support to claim that another theory has no evidence.)

To wrap it all up, consider this sample argument:

My friend claims that my professor doesn't like me. In support, he says that this would explain why my professor keeps giving me Fs on my assignments. But there's no evidence that my professor doesn't like me, since my F grades on the assignments can already be explained by the fact that I turned in all my assignments late.

The argument above does not have to assume any principle about what would make my friend's hypothesis correct. The argument is actually saying my friend's claim has no evidence. In addition, the argument never says that my friend's theory that my professor is biased against me would not explain my Fs. It's just saying that we don't need to go to that theory because the lateness of the assignments is enough to explain the Fs.