Q21 - Two doctrines have been greatly

[b91302310]

When I read all the answer choices, I found that no one seems correct. Even after reading the official explanation, I'm still confused about (A).

The conclusion of the argument is that both doctrines are mistaken.

The supporting premise is that there have been events that were due both economic factors and the nature of early childhood.

Here is my understanding how (A) could be correct. If the first doctrine does not preclude any noneconomic factors from explaining events, it is possibe for the first doctrine to claim that early childhood could also be a factor. If so, then (A) could be consisten with the argument's supporting premise. Thus, the conclusion that both two doctrines are mistaken will be challenged becasue the first one could be correct. Thus, (A) must be an assumption of the argument.

So, could any one explain it more clearly and let me know what I'm missing ?

Thanks.

[ManhattanPrepLSAT1]

Good question, thanks for bringing this one to the forum! This one is interesting in it's structure.

The argument's conclusion is closer to being valid than might suspect initially. The conclusion is that both doctrines are wrong. The way the second is phrased, one might argue that it excludes non-psychological explanations. If that's the case, then the second of the doctrines has been proven to be mistaken. But what about the first doctrine. The language there does not suggest the doctrine accounts for historical events exclusively with economic factors.

The assumption of the argument is that the first doctrine shares the same flaw as the second doctrine. Answer choice (A) says exactly this.

It's easy to miss that the first doctrine might not be mistaken even if the second one is. And since the second one is closer to being proven mistaken, it's easy to be thrown off track when seeking the flaw in the argument.

Does that answer your question?

[b91302310]

Thanks, I think that I get a better understanding of the logic of the question. However, I'm still stuck in the language. Could we diagram the sentence that "the explanation of any historical event must appeal to economic factors" as "historical events --> explained by economic factors"? If so, it will share the same meaning with (A), that is, only economic factor could explain all historical events.(other noneconomic factors are excluded) Thus, since it already has the same flaw as stated by the second doctrine, why should we have to put (A) as the assumption?

Is there anything I'm missing in the interpretation?

[ManhattanPrepLSAT1]

The answer to your first question is that the conditional relationship can be expressed as you have stated it.

"the explanation of any historical event must appeal to economic factors" as "historical events --> explained by economic factors"

But that doesn't mean that it would share the same meaning as answer choice (A). Answer choice (A) precludes other factors that could be used in explaining historical events. The statement you have written above however does not preclude other factors, but simply requires the inclusion of economic factors.

Does the distinction make sense?

[jlz1202]

I re-read the stimulus several times but don't see how the second doctrine excludes non-psychological factors? The conclusion says both are wrong, but according to A, I can only find it suggesting the 2nd doctrine are wrong: "the 1st doctrine precludes any noneco factors..." --doesn't it suggest that not all events could be explained by psychological factors thus the 2nd doctrine are wrong? But what about the 1st doctrine? It does not show the 1st doctrine wrong?

Could any one please help explicate the stimulus and answer A? I am sooooooooo confused!

Thanks in advance!

[cdjmarmon]

What is even being said in this argument?

It starts by talking about 2 doctrines and how they effect how historical events need to be explained. Then says they are mistaken in how a historical event needs to be explained, because there has been events that were caused by both economic forces and the early childhood experiences of the participants?

So the correct answer says theres something wrong about the first doctrine and leaves the second doctrine as ok?

[timmydoeslsat]

What is even being said in this argument?

It starts by talking about 2 doctrines and how they effect how historical events need to be explained. Then says they are mistaken in how a historical event needs to be explained, because there has been events that were caused by both economic forces and the early childhood experiences of the participants?

So the correct answer says theres something wrong about the first doctrine and leaves the second doctrine as ok?

You are correct in what is being stated in this argument.

Answer choice A is necessary for the first doctrine to be mistaken.

Although the conclusion is that both are mistaken. So this argument is still not valid with (A) inserted into argument. The second doctrine is left untouched so we are not sure that it is mistaken.

[ManhattanPrepLSAT1]

Great discussion! I think I see it a bit differently though, and I'd love to hear what you think.

The discussion so far seems to suggest that as stated in the stimulus neither doctrine in the stimulus is mistaken. But I would suggest that the argument does a pretty good job of showing that the second doctrine is mistaken, but simply fails to establish that the first doctrine is mistaken.

The first doctrine says that an explanation must appeal to economic factors. It does not say that it must appeal to solely economic factors, and so the evidence that there are situations that were due both to economic forces and to the nature of early childhood would not establish the first doctrine to be mistaken. Assuming answer choice (A) though is an assumption of the first doctrine being mistaken.

I do see the second doctrine as having been established to be mistaken. If it attempts to account psychologically for all historical events, the explanation is a psychological one. Which, in light of the evidence would be mistaken since it would have failed to account for the economic forces.

So, when hunting for the assumption, I was already looking for the gap on the way to establishing that the first doctrine was mistaken.

Incorrect Answers

(B) need not be assumed, since the second doctrine could appeal to other psychological factors and still be mistaken. This answer rules out the possibility that the second doctrine appeals to economic factors, but also rules out more than what is needed to establish the conclusion and focuses on the doctrine that had already been established to be mistaken and not the gap in the reasoning.
(C) is irrelevant. No relative comparison as to the impact of these various factors need be assumed.
(D) need not be assumed. We know that no doctrine can appeal to solely economic or psychological factors and still explain all historical phenomena, but why should there be both explanations already made for any given historical event?
(E) places both factors in the explanation to any event, when we need to assume instead that no explanation that appeals solely to economic or to psychological factors will explain all historical phenomena. So, there must be at least one event that requires both economic and psychological explanations, but not that any event requires both.

Let me know what you guys think!

#officialexplanation

[jm.kahn]

Why is A necessary? Isn't it a superset of a necessary assumption as it includesany noneconomic factors. Can experts explain?

The first doctrine holds that any historical event requires economic factors. But, there have been events that are due to both economic and psycho factors. Therefore, this first doctrine is wrong.

We have to find the necessary assumption for the above argument.

Premises-1: Doctrine is: HE (historical event) -> EF (economic factors)
Premise-2: HE -> EF && PF (psycho factors)
Conclusion: Doctrine is wrong

The conclusion can be drawn only if the doctrine about Historical events precludes Psychological factors -- It doesn't have to preclude all ~EF (answer choice A says that it has to preclude all ~EF); it only has to preclude PF.

For example, non-economic factors can include both psychological and environmental factors. What A is saying is that for the conclusion to be drawn we must assume that all non-economic factors (psycho and environ) must be precluded by the doctrine. But this is an overreach -- assuming it justifies the argument, but it is not necessary to the argument. The only necessary part is that psycho factors (and not all non-economic factors) are precluded from the doctrine.

Thanks in advance

[Yangyi.vita]

Interesting. When I first read the two premises, I thought they were like: all for one and one for all. But sadly I later figured out they were actually the opposite: one for all (economic factor for all historical event, and not exclude other factors) and all for one. But not quite sure about the latter one. What does it mean on earth "account psychologically"? Why from "psychologically" can we know that it suggests psychological factor only?

[Camiller]

I have read LSACs explanation for this question multiple times, and I am still struggling to make sense of this question. Based on LSACs reasoning as to why (E) is incorrect, I am struggling to understand how it is that (A) is correct/considered a necessary assumption.

(E) states: "Appeals to both economic and psychological factors are needed to understand any historical event properly." LSACs explanation as to why (E) is incorrect asserts that the argument does not "depend on both economic and psychological factors being needed to explain every historical event."

Why is this same logic not applied to (A)? (A) states: "The first doctrine precludes any noneconomic factors in explanations of historical events." How is (A) a necessary assumption? Doesn't it go too far? The argument does not depend on the first doctrine precluding any noneconomic factors in the explanations of historical events, right? The evidence is limited to the fact that there have been "events the were due both to economic forces and to the nature of the early childhood experiences of the major participants in the event." So I can see how the argument might depend on the first doctrine precluding psychological factors specifically related to the nature of early childhood experiences, but how is it that "precludes any noneconomic factors" is not going too far?


Furthermore...

The argument core:
PREMISE: There have been events the were due both to economic forces and to the nature of the early childhood experiences of the major participants in the event
CONCLUSION: Both doctrines (Doctrine 1: any historical event must appeal to economic factors; Doctrine 2: all historical events accounted for psychologically) are mistaken.

LSAC asserts that: "the first doctrine is committed only to the position that any adequate historical explanation must include an appeal to economic factors, thereby leaving open the possibility that noneconomic factors are relevant."

The evidence shows that there were events due to both economic. To explain this evidence, "any adequate historical explanation must include an appeal to economic factors". How is (A), which states: "The first doctrine precludes any noneconomic factors in explanations of historical events", necessary to both documents being mistaken? More specifically, how does this show that doctrine 1 is mistaken? Even if (A) were true, the evidence still seems to show that any adequate historical explanation must include an appeal to economic factors, which is exactly what doctrine 1 holds. This does not show that doctrine 1 is false.

[maryadkins]

I think the clearest way to see it is to negate:

(A), negated: "The first doctrine does not preclude any noneconomic factors in explanations of historical events."

Oh. Well, then, it can include psychology and still not be wrong. The argument falls apart if we negate (A).

(E), negated: "Appeals to both...are not needed to understand any [as in all] historical event[s] properly." The key here is that we don't need them both to be necessary for EVERY historical event (LSAC's word, as well: "every"). The conclusion is just that there are SOME events that involved both factors. I see how the way this is worded is tricky, though!

[megsvyas]

After reading this question, I thought "the argument assumes that the two doctrines are mutually exclusive" --- in other words, it sure does seem that the argument thinks that both doctrines can't simultaneously be applied in understanding a historical event, i.e. they both individually must prevent the other from being used.

I thought the "argument assumes the doctrines are mutually exclusive" was an easy way to look at this flaw -- and (a) essentially guarantees that the first doctrine was in fact promoting exclusivity. Hope this helps someone out there!

[PatelM544]

I was having issues with this question too but I believe that I may have found a solution.
So, I first saw that both Psychology (P) and Economic factors (EF) are children of Historical events (HE), but I was wrong. They are sequential:

Premises: P - > HE -> EF
Conclusion: n P and n EF

Question: What do we need to confirm the Conclusion? / What is the prediction?
Answer: something that confirms the conclusion that P and EF are wrong.

So, how could we show that both P and EF are wrong? By pointing out an issue within their scopes. (A) says that there is an issue with EF that makes it wrong. Back to our sequence
n EF -> n HE -> n P

This is why (A) is the correct AC; it points out there is an issue with the EF that makes it wrong. Then, if EF is wrong, then everything falls apart including P and HE.

(B) Is not correct because it points out that P is wrong, but who cares if it is wrong or not? It won't point out that both P and EF are wrong
(C) This places H in the middle and confirms that both EF and P influence H equally
(D) Out of scope
(E) Claims taht we need to know more about P and EF in order to understand H. But nobody cares about that, when we need only to explain why P and EF are wrong.

[LizaK873]

I dug into this question way too much. Hope this helps others.
Tldr:

Premise:
- A says Econ.
- B says psych.
- Econ + psych coexist in at least one explanation.

Answer/required assumption (see **):
- [A says no psych]. [B says no econ].
- aka, [A says econ] + [event has econ & psych] + [A is wrong] == [A says no psych]

Conclusion:
- A and B are false.


So anything that claims [A says no psych] and [B says no econ] are correct answers.
Note: The correct answer is not ["A says econ" is false] (as this question tries to mislead you to look for) because you cannot invalidate premises.
Note: Neither Doctrine A nor B say anything regarding exclusivity. Neither premises imply no other factors can exist. Both leave the options open for other factors.

Longer explanation:

Premises:
1. Doctrine A says all historical explanations have an economic factor.
2. Doctrine B says all historical explanations have a psychological factor.
3. There has been events with both economic and psychological factors in its historical explanation.

Conclusion:
1. Doctrine A is false and doctrine B is false.

Missing link, aka the missing required (sufficient) assumption:
1. Doctrine A makes a claim such that psych factors cannot exist in any historical explanations.
2. Doctrine B makes a claim such that econ factors cannot exist in any historical explanations.

Why the missing link (skip if you already arrived at it on your own)
- At least one historical explanation with both econ + psych factors exist -> _____ -> Doctrine A and B is false.
- In order for Doctrine A to be false, all that's required is that A claims anything that says psych factors cannot exist.
- *Why? Say event "H" has both econ + psych factors. Well in premise 1, A says econ exists. So the only way A can be wrong, is if it says <no psych> factors exist for this event.**
- Note, A saying "no psych factors exist" is just as valid as an answer as "no other factors exist other than economic", because the latter implies the former.
- Same reasoning for B.
- note: the missing link does not invalidate any of the premises (because premises cannot be invalidated).


Answers:
A. This makes up one of the possible required assumptions. "A says no other factors than econ exist", when H has a factor other than econ, makes one part of the conclusion true. However, I ruled this out mistakenly because it was missing the other required assumption. (see "my own mistake" below)
B. "places importance only on" does not translate to "no other factors other than psych exist". All it says at most, is that other factors aren't that important, NOT that they don't exist.
C. This restates premise #3, and does nothing to state "A says no psych" or "B says no econ".
D. Same as C.
E. This doesn't say "no psych" nor "no econ", the ONLY two required statements that make conclusion come true. In fact, if E is true, doctrine A and B can still be correct(!): "econ and psych are both required" and "doctrine A says all have psych" can coexist.


My own mistake: A subset of the expected sufficient (required) assumption is still a correct one, as the argument still depends on it, even if it is not complete. As in,

X + Y -> Z is equivalent to X -> Z + Y -> Z

And answer A covered just X -> Z, and thinking that missing Y -> Z made it wrong. The conclusion depends on both yes, but that doesn't make answer A false based on how the question is worded, as "x -> z" is still an assumption the conclusion requires. Answer A being true does NOT say Y -> Z isn't true too.

----

Replying to an earlier comment regarding superset:
Both "A says no psych" and "A says nothing but econ" fill the required. It doesn't matter how large the scope of the assumption is or how far it goes, or other things it assumes, but only that A) it proves the conclusion true and B) does not invalidate any of the premises.