Q11 - Special kinds of cotton that

[Slymobius]

It's a MBT question. I "backed" my way into this one and got it correct. By "backed" I mean that I found the four incorrect answers which I kind of feel was the easiest way on this one. Most answers are OOS/make un-inferable assumptions for the reasons of:

The opposite of "long-fiber" cotton is "not long-fiber" cotton. It does not mean "short-fiber" cotton (it could be medium). Eliminate A,D

The opposite of "commercially/machine" made is "not commercially/machine" made. It does not mean "hand-made" (although one would think so). Although unlikely, it could be made by animal made or alien made or naturally made. Eliminate C

Stimulus doesn't talk about garments, finished products, at all. It's more concerned with the raw materials. Eliminate E

This leaves us with the credited answer B. Notice it says "not commercially viable". "Spun by hand" in this choice is not OOS because the answer is saying that any way other than machine spun is not commercially viable and uses "spun by hand" as the example because we know if it's not machine made then it's not commercially viable. I feel like this answer also "primes" you to choose answer C if you aren't careful.

Key? You have to realize that you must define things by what they are not.

Geeks, your take on this analysis? Also, the most efficient way to work the question forward?

[christine.defenbaugh]

Some wonderful analysis going on here Slymobius! Particularly good work on realizing that while we don't know anything about 'things that are hand spun', we do know something about 'things that are ONLY hand spun' (because they are NOT machine spun).

A few important things to point out. While this is an inference question, it is not actually a "must be true" question. There are a handful of different inference questions, with small distinctions. The reason that is significant is that only for "must be true" questions does the answer need to be 100%, mathematically and definitively provable. For this more generic inference question, an extremely high likelihood will do just fine.

Also, in the wrong answers, it may be more helpful to note the bad comparisons getting made in every wrong answer choice before getting too caught up in the categories themselves.

You ask for a strong front-end approach to this question, and the reality is that there isn't one. Inference questions, by their very nature, have unpredictable answers. It would be a waste of time an energy to attempt to predict exactly where the test-writers will choose to take the correct answer. Backing in to the right answer, or working from wrong-to-right is the rockstar approach to these every time!

Let's break it down. Treating our stimulus as a list of interesting facts, we've got:

1) green/brown cotton has been around since 1930s
2) Only became commercially feasible recently
3) Became com. feas. only when a long-fiber that could be spun by machine was bred
4) green/brown cotton doesn't need to be dyed
5) plants for green/brown cotton don't spend $$ on dye
6) plants for green/brown cotton don't have eco hazards of dumping dye/by-products

The only one we can support is (B). Green/brown cotton only became commercially viable with the advent of a long-fiber that got machine-spun, so it seems reasonable that green/brown cotton spun only by hand (and therefore not by machine) isn't commercially viable. If it had been, why would we have needed to wait for the new 'spun by machine' long fiber?

For the formal logic geeks: Notice that the commercial feasibility occurred "only when" someone bred a long-fiber for machine-spinning.



The Infernal Uninferable
(A) "ecologically safer" - comparison trap! The only thing we know about ecological safety is that dumping dye = ecologically hazardous. We never compared two different items ecological safety.
"short-fibered cotton" - we know nothing about this category.
(C) "more ecologically safe" - comparison trap! Just like (A).
"hand-spun" - we know nothing about this category.
(D) "economically competitive" - comparison trap! I know, it isn't saying 'more than/less that', but 'equals to' is still a comparison. The only thing we know about economic competitiveness is that brown/green cotton only got to come to the party recently. We never compare any group's economic competitiveness to any other group's.
"short-fibered regular cottons" - we know nothing about this category.
"synthetic fabrics" - we know nothing about this category.
(E) "less expensive" - comparison trap! The only thing we know about expenses is that dye is expensive, and green/brown fibers don't need it. We never compare any item's expensiveness to any other item's.
"garments" - we know nothing about these.
"regular cotton" - we know nothing about this.


Every wrong answer has an irrelevant comparison, in addition to having items or categories that are out of scope. Great work Slymobius! Let me know if you would like additional clarification on any point here!

[dangilomartin]

Great posts. I would like to point out that I think the key to "B" is the ONLY. Without that small qualifier this answer would be incorrect. I say this because I passed by that "only" and eliminated incorrectly for that very reason.

[keonheecho]

Some wonderful analysis going on here Slymobius! Particularly good work on realizing that while we don't know anything about 'things that are hand spun', we do know something about 'things that are ONLY hand spun' (because they are NOT machine spun).

A few important things to point out. While this is an inference question, it is not actually a "must be true" question. There are a handful of different inference questions, with small distinctions. The reason that is significant is that only for "must be true" questions does the answer need to be 100%, mathematically and definitively provable. For this more generic inference question, an extremely high likelihood will do just fine.

Also, in the wrong answers, it may be more helpful to note the bad comparisons getting made in every wrong answer choice before getting too caught up in the categories themselves.

You ask for a strong front-end approach to this question, and the reality is that there isn't one. Inference questions, by their very nature, have unpredictable answers. It would be a waste of time an energy to attempt to predict exactly where the test-writers will choose to take the correct answer. Backing in to the right answer, or working from wrong-to-right is the rockstar approach to these every time!

Let's break it down. Treating our stimulus as a list of interesting facts, we've got:

1) green/brown cotton has been around since 1930s
2) Only became commercially feasible recently
3) Became com. feas. only when a long-fiber that could be spun by machine was bred
4) green/brown cotton doesn't need to be dyed
5) plants for green/brown cotton don't spend $$ on dye
6) plants for green/brown cotton don't have eco hazards of dumping dye/by-products

The only one we can support is (B). Green/brown cotton only became commercially viable with the advent of a long-fiber that got machine-spun, so it seems reasonable that green/brown cotton spun only by hand (and therefore not by machine) isn't commercially viable. If it had been, why would we have needed to wait for the new 'spun by machine' long fiber?

For the formal logic geeks: Notice that the commercial feasibility occurred "only when" someone bred a long-fiber for machine-spinning.



The Infernal Uninferable
(A) "ecologically safer" - comparison trap! The only thing we know about ecological safety is that dumping dye = ecologically hazardous. We never compared two different items ecological safety.
"short-fibered cotton" - we know nothing about this category.
(C) "more ecologically safe" - comparison trap! Just like (A).
"hand-spun" - we know nothing about this category.
(D) "economically competitive" - comparison trap! I know, it isn't saying 'more than/less that', but 'equals to' is still a comparison. The only thing we know about economic competitiveness is that brown/green cotton only got to come to the party recently. We never compare any group's economic competitiveness to any other group's.
"short-fibered regular cottons" - we know nothing about this category.
"synthetic fabrics" - we know nothing about this category.
(E) "less expensive" - comparison trap! The only thing we know about expenses is that dye is expensive, and green/brown fibers don't need it. We never compare any item's expensiveness to any other item's.
"garments" - we know nothing about these.
"regular cotton" - we know nothing about this.


Every wrong answer has an irrelevant comparison, in addition to having items or categories that are out of scope. Great work Slymobius! Let me know if you would like additional clarification on any point here!

Hi Christine,
Can't A, C and D also be eliminated because the stimulus is only talking about special kinds of cotton, whereas the answer choices are talking about different groups of cotton that don't necessarily relate to the kinds of cotton in the stimulus?

Thank you in advance

[roflcoptersoisoi]

Some wonderful analysis going on here Slymobius! Particularly good work on realizing that while we don't know anything about 'things that are hand spun', we do know something about 'things that are ONLY hand spun' (because they are NOT machine spun).

A few important things to point out. While this is an inference question, it is not actually a "must be true" question. There are a handful of different inference questions, with small distinctions. The reason that is significant is that only for "must be true" questions does the answer need to be 100%, mathematically and definitively provable. For this more generic inference question, an extremely high likelihood will do just fine.

Also, in the wrong answers, it may be more helpful to note the bad comparisons getting made in every wrong answer choice before getting too caught up in the categories themselves.

You ask for a strong front-end approach to this question, and the reality is that there isn't one. Inference questions, by their very nature, have unpredictable answers. It would be a waste of time an energy to attempt to predict exactly where the test-writers will choose to take the correct answer. Backing in to the right answer, or working from wrong-to-right is the rockstar approach to these every time!

Let's break it down. Treating our stimulus as a list of interesting facts, we've got:

1) green/brown cotton has been around since 1930s
2) Only became commercially feasible recently
3) Became com. feas. only when a long-fiber that could be spun by machine was bred
4) green/brown cotton doesn't need to be dyed
5) plants for green/brown cotton don't spend $$ on dye
6) plants for green/brown cotton don't have eco hazards of dumping dye/by-products

The only one we can support is (B). Green/brown cotton only became commercially viable with the advent of a long-fiber that got machine-spun, so it seems reasonable that green/brown cotton spun only by hand (and therefore not by machine) isn't commercially viable. If it had been, why would we have needed to wait for the new 'spun by machine' long fiber?

For the formal logic geeks: Notice that the commercial feasibility occurred "only when" someone bred a long-fiber for machine-spinning.



The Infernal Uninferable
(A) "ecologically safer" - comparison trap! The only thing we know about ecological safety is that dumping dye = ecologically hazardous. We never compared two different items ecological safety.
"short-fibered cotton" - we know nothing about this category.
(C) "more ecologically safe" - comparison trap! Just like (A).
"hand-spun" - we know nothing about this category.
(D) "economically competitive" - comparison trap! I know, it isn't saying 'more than/less that', but 'equals to' is still a comparison. The only thing we know about economic competitiveness is that brown/green cotton only got to come to the party recently. We never compare any group's economic competitiveness to any other group's.
"short-fibered regular cottons" - we know nothing about this category.
"synthetic fabrics" - we know nothing about this category.
(E) "less expensive" - comparison trap! The only thing we know about expenses is that dye is expensive, and green/brown fibers don't need it. We never compare any item's expensiveness to any other item's.
"garments" - we know nothing about these.
"regular cotton" - we know nothing about this.


Every wrong answer has an irrelevant comparison, in addition to having items or categories that are out of scope. Great work Slymobius! Let me know if you would like additional clarification on any point here!

Hi Christine,
Can't A, C and D also be eliminated because the stimulus is only talking about special kinds of cotton, whereas the answer choices are talking about different groups of cotton that don't necessarily relate to the kinds of cotton in the stimulus?

Thank you in advance

Yes, essentially you're on the right track. (A) is wrong for a number of reasons one of which you mentioned: We're talking about brown or green long fibered variety that's spun by a machine that is commercially feasible and presumably short fibered cotton that is not spun by a machine. This answer choice however talks about ALL long fibered cotton, it baits us into making the unwarranted assumption that because long fibered green or brown cotton can be produced without any ecological hazards that that must also be true for all long fibered cotton, we can't just over extrapolate like that, we have no clue. Furthermore we're given no info as to the environmental impact of short fibered cotton.

In regards to (C) Hand spun cotton isn't even mentioned in the stimulus. We were told that at one point long fibered was produced by a machine, so therefore we can conclude that before the advent of this machine fibre could not/was not produced by a machine, however that doesn't necessarily mean the it was spun by hand. Like OP pointed out, not spun by machine does not equate to being spun by hand, perhaps it was formed in another way. Even if we conceded that hand spun cotton was the only way it could be spun if not produced by a machine, again we're given no info as to the environmental impact of cotton that is not spun using a machine so we cannot make the comparison.

(D) Absolutely not.. We're in the world is this supported in the stimulus? Neither economic competitiveness nor synthetic garments are mentioned. I feel like the LSAT is just insulting our intelligence by including this as an answer choice.

[roflcoptersoisoi]

Some wonderful analysis going on here Slymobius! Particularly good work on realizing that while we don't know anything about 'things that are hand spun', we do know something about 'things that are ONLY hand spun' (because they are NOT machine spun).

A few important things to point out. While this is an inference question, it is not actually a "must be true" question. There are a handful of different inference questions, with small distinctions. The reason that is significant is that only for "must be true" questions does the answer need to be 100%, mathematically and definitively provable. For this more generic inference question, an extremely high likelihood will do just fine.

Also, in the wrong answers, it may be more helpful to note the bad comparisons getting made in every wrong answer choice before getting too caught up in the categories themselves.

You ask for a strong front-end approach to this question, and the reality is that there isn't one. Inference questions, by their very nature, have unpredictable answers. It would be a waste of time an energy to attempt to predict exactly where the test-writers will choose to take the correct answer. Backing in to the right answer, or working from wrong-to-right is the rockstar approach to these every time!


Let's break it down. Treating our stimulus as a list of interesting facts, we've got:

1) green/brown cotton has been around since 1930s
2) Only became commercially feasible recently
3) Became com. feas. only when a long-fiber that could be spun by machine was bred
4) green/brown cotton doesn't need to be dyed
5) plants for green/brown cotton don't spend $$ on dye
6) plants for green/brown cotton don't have eco hazards of dumping dye/by-products

The only one we can support is (B). Green/brown cotton only became commercially viable with the advent of a long-fiber that got machine-spun, so it seems reasonable that green/brown cotton spun only by hand (and therefore not by machine) isn't commercially viable. If it had been, why would we have needed to wait for the new 'spun by machine' long fiber?

For the formal logic geeks: Notice that the commercial feasibility occurred "only when" someone bred a long-fiber for machine-spinning.



The Infernal Uninferable
(A) "ecologically safer" - comparison trap! The only thing we know about ecological safety is that dumping dye = ecologically hazardous. We never compared two different items ecological safety.
"short-fibered cotton" - we know nothing about this category.
(C) "more ecologically safe" - comparison trap! Just like (A).
"hand-spun" - we know nothing about this category.
(D) "economically competitive" - comparison trap! I know, it isn't saying 'more than/less that', but 'equals to' is still a comparison. The only thing we know about economic competitiveness is that brown/green cotton only got to come to the party recently. We never compare any group's economic competitiveness to any other group's.
"short-fibered regular cottons" - we know nothing about this category.
"synthetic fabrics" - we know nothing about this category.
(E) "less expensive" - comparison trap! The only thing we know about expenses is that dye is expensive, and green/brown fibers don't need it. We never compare any item's expensiveness to any other item's.
"garments" - we know nothing about these.
"regular cotton" - we know nothing about this.


Every wrong answer has an irrelevant comparison, in addition to having items or categories that are out of scope. Great work Slymobius! Let me know if you would like additional clarification on any point here!

Correct me if i'm wrong but the "when" is not immediately preceded by "only" which would make it a trigger for a necessary condition, there are 5 words between "only" and "when". I know that "when" introduces a sufficient condition, so wouldn't : Long fibered variety that can be spun by a machine, be the sufficient condition and commercially feasible the necessary one?

[DavidH327]

I could see why incorrect answers don't make sense but
I thought correct answer choice B would also be an illegal reverse

Because stimulus says:
WHEN a long-fibered variety that can be spun by machine was finally bred, cotton became commercially feasible
M --> CF

And this answer choice says:
cottons that can be spun only by hand (not Machine) are not commercially viable.
-M --> -CF

What if cottons that can be spun only by hand ARE commercially viable but it was never developed until 1930s when they introduced the machine??

Some wonderful analysis going on here Slymobius! Particularly good work on realizing that while we don't know anything about 'things that are hand spun', we do know something about 'things that are ONLY hand spun' (because they are NOT machine spun).

A few important things to point out. While this is an inference question, it is not actually a "must be true" question. There are a handful of different inference questions, with small distinctions. The reason that is significant is that only for "must be true" questions does the answer need to be 100%, mathematically and definitively provable. For this more generic inference question, an extremely high likelihood will do just fine.

Also, in the wrong answers, it may be more helpful to note the bad comparisons getting made in every wrong answer choice before getting too caught up in the categories themselves.

You ask for a strong front-end approach to this question, and the reality is that there isn't one. Inference questions, by their very nature, have unpredictable answers. It would be a waste of time an energy to attempt to predict exactly where the test-writers will choose to take the correct answer. Backing in to the right answer, or working from wrong-to-right is the rockstar approach to these every time!

Let's break it down. Treating our stimulus as a list of interesting facts, we've got:

1) green/brown cotton has been around since 1930s
2) Only became commercially feasible recently
3) Became com. feas. only when a long-fiber that could be spun by machine was bred
4) green/brown cotton doesn't need to be dyed
5) plants for green/brown cotton don't spend $$ on dye
6) plants for green/brown cotton don't have eco hazards of dumping dye/by-products

The only one we can support is (B). Green/brown cotton only became commercially viable with the advent of a long-fiber that got machine-spun, so it seems reasonable that green/brown cotton spun only by hand (and therefore not by machine) isn't commercially viable. If it had been, why would we have needed to wait for the new 'spun by machine' long fiber?

For the formal logic geeks: Notice that the commercial feasibility occurred "only when" someone bred a long-fiber for machine-spinning.



The Infernal Uninferable
(A) "ecologically safer" - comparison trap! The only thing we know about ecological safety is that dumping dye = ecologically hazardous. We never compared two different items ecological safety.
"short-fibered cotton" - we know nothing about this category.
(C) "more ecologically safe" - comparison trap! Just like (A).
"hand-spun" - we know nothing about this category.
(D) "economically competitive" - comparison trap! I know, it isn't saying 'more than/less that', but 'equals to' is still a comparison. The only thing we know about economic competitiveness is that brown/green cotton only got to come to the party recently. We never compare any group's economic competitiveness to any other group's.
"short-fibered regular cottons" - we know nothing about this category.
"synthetic fabrics" - we know nothing about this category.
(E) "less expensive" - comparison trap! The only thing we know about expenses is that dye is expensive, and green/brown fibers don't need it. We never compare any item's expensiveness to any other item's.
"garments" - we know nothing about these.
"regular cotton" - we know nothing about this.


Every wrong answer has an irrelevant comparison, in addition to having items or categories that are out of scope. Great work Slymobius! Let me know if you would like additional clarification on any point here!

[ohthatpatrick]

How would you diagram this sentence?

American citizens can only run for President when they are at least 35 years old.



Is that saying
IF you are at least 35, THEN you can run for President

or saying
IF you are not at least 35, THEN you can't run for President



It's the second one. Being 35+ doesn't guarantee that you can for President (after all, felons can't run for President). But being under 35 guarantees that you can't run for President.

So here's how the rule should look:
~ 35+ --> Can't run for Pres
Can run for Pres --> 35+

Structurally, we would be using the conditional trigger "only when", which is the same as "only if", to realize that whatever idea follows the "only when" is a necessary condition that belongs on the right side.

These two sentences mean the same thing:
American citizens can run for President only when they are at least 35.
American citizens can only run for President when they are at least 35.

Grammatically, you can keep the "only when" together or break it apart, makes no difference to the logic or meaning.

Hope this helps.

[JonghyukJ247]

Does "only if" mean the same when it's separated?

just like "only X when Y" means the same as "X only when Y"

is "X only if Y" identical to "only X if Y"?

Should we always consider Y is the necessary one?