Hi Karishma - thank you so much for what you do

Question from the Powerscore Guide

Why is E wrong ?

The first sentence clearly says Blood tests used to determine pregnancy can at times be inconclusive

Hence E seemed right to me

Thoughts ?

Hey imSKR,

Done. Please check the link.
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Hey Rachit4126

Option (B) is irrelevant. How many are prosecuted is not a part of our argument.

Our argument only deals with this:

Avg rate of violent crime in states with strict gun-control laws was 50% higher than the average rate in the eleven states where strict gun-control laws have never been passed.

Conclusion: One way to reduce violent crime is to repeal strict gun control laws.

The argument is comparing states with strict gun control laws with states without strict gun control laws. Since states with strict laws have higher rate of violent crime, the argument proposes to repeal strict laws.
The point is only about crime statistics, not about how many are prosecuted for these crimes.
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Hey jabhatta@umail.iu.edu

When you establish that if I own a Lamborghini, I must be rich, it means it you have that car, you are rich (how you got it is irrelevant). Even if a friend gave it to you, you are rich. Just by owning the car you are rich.
So if you are not rich, then you do not have it because if you had it, you would have been rich.
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Good Afternoon Mam

This is Nikhil and I am doing GMAT preparation from so long (11 months maybe). I want to take some tips from you regarding CR. I completed the power score CR bible and the results are descent. During practice, my accuracy lies between 85%-95% without time constraints. But i don't know that when it comes to application in exam, i spend long time doing CR questions. As a result, i get short at time always and unfortunately, a series of wrong CR answers in the last. I have a good conceptual understanding of CR but application wise, I am not good though. Please suggest me for how to overcome this problem. 2 mins for CR questions seems very little to me.

With Regards
Nikhil Seth

Hey jabhatta@umail.iu.edu

The test can give one of the three results - positive/negative/inconclusive.

Inconclusive does not mean that a negative test can be false or a positive test can be false. It means that the test is unable to determine whether the woman is pregnant or not. Say the test shows a value of less than 1 for negative and more than 10 for positive. But if the value lies between 1 and 10, it is inconclusive. It means it is unable to determine whether the woman is pregnant or not. The result is not wrong; it is inconclusive.
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Thank you so much mam, i will do that.

Thanks VeritasKarishma

Hi VeritasKarishma - Thank you for everything.


For Strengthening CR questions

-- why is a link that makes the conclusion more valid an example of a strengthener ? Isn't that an assumption ?

For example, in the question below -- The OA is B

Isn't B more of an assumption that has to be true, than an actual strengthener.

Per my understanding, assumptions and strengtheners are completely different

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Astronomer: Most stars are born in groups of thousands, each star in a group forming from the same parent cloud of gas. Each cloud has a unique homogeneous chemical composition. Therefore whenever two stars have the same chemical composition as each other, they must have originated from the same cloud of gas.

Which of the following, if true, would most strengthen the astronomer's argument?

(A) In some groups of stars, not every star originated from the same parent cloud of gas.
(B) Clouds of gas of similar or identical chemical composition may be remote from each other.
(C) Whenever a star forms, it inherits the chemical composition of its parent cloud of gas.
(D) Many stars in vastly different parts of the universe are quite similar in their chemical compositions.
(E) Astronomers can at least sometimes precisely determine whether a star has the same chemical composition as its parent cloud of gas.

B is irrelevant

i. Necessary condition
ii. something that makes conclusion strengthen

Assumption: i and ii both require
Strengthener : i is not required ; ii require

ughhh --yes OA is (C), not (B). My apologies

C -- seems to me a necessary condition for the argument to make sense.

If the question was instead -- "find the assumption" -- wouldn't C ALSO be your answer ?

Not necessarily.

There could be many assumptions such as:-
1. Chemical composition doesn't change in later stage
2. once inherited properties would have no influence of external factors .


it is a strengthen statement but it didn't mention that in that it is not viable to change due to some chemical reaction at later stage ( e.g.: children inherit behavior from parents but later children do get change due to influence of society , friends etc. on them)
what if chemical composition is changed then this statement would not be valid as an assumption anymore.

Hi Karishma,

Can you help me confirm my understanding regarding the use of necessary and sufficient conditions in these 2 conclusions.

Voters commonly condemn politicians for being insincere, but politicians often must disguise their true feelings when they make public statements. If they expressed their honest views—about, say, their party's policies—then achieving politically necessary compromises would be much more difficult. Clearly, the very insincerity that people decry shows that our government is functioning well.
(A) Achieving political compromises is not all that is necessary for the proper functioning of a government.
My understanding here is that insincerity is necessary for our govt to function well.
Premise: honesty -> political compromises difficult
In other words: Political compromises -> insincerity
***Assumption*** govt functioning well -> political compromises
Conclusion: Govt well-> insincerity
Weakener : political compromises not all that is necessary.. indicating the presence of other necessary conditions.

However,
In the below question
Cognitive scientist: Using the pioneering work of comparative psychologist Gordon Gallup as a model, several studies have investigated animals' capacity for mirror self-recognition (MSR). Most animals exposed to a mirror respond only with social behavior, such as aggression. However, in the case of the great apes, repeated exposure to mirrors leads to self-directed behaviors, such as exploring the inside of the mouth, suggesting that these animals recognize the reflection as an image of self. The implication of these studies is that the great apes have a capacity for self-awareness unique among nonhuman species.
B. If an animal does not have the capacity for MSR, it does not have the capacity for self-awareness.
Assumption 1. MSR is necessary for Self Awareness. Without this the conclusion doesn't hold. The correct option is the contrapositive version of this.
Self Awareness -> MSR

But does the unique in the conclusion even imply that MSR is sufficient?

so you are suggesting that C is BOTH an Assumption & Strengthener as of now.

If C was Whenever a star forms, it inherits the chemical composition of its parent cloud of gas in the short term only . -- this tweak would still be a strengthener but not an assumption ?

Note that an assumption is a special case of strengtheners. An assumption strengthens the conclusion and is, in fact, necessary for the conclusion.
This question asks for an option that will strengthen the argument. So you need to look for just that. Now, whether it is an assumption too is irrelevant.
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Hey kagrawal16,

Voters commonly condemn politicians for being insincere, but politicians often must disguise their true feelings when they make public statements. If they expressed their honest views—about, say, their party's policies—then achieving politically necessary compromises would be much more difficult. Clearly, the very insincerity that people decry shows that our government is functioning well.


Premise: Political compromises need insincerity.

Conclusion: Insincerity shows that our govt is functioning well.

How do we link political compromises with govt is functioning well? The premises talk about political compromises and insincerity only. The premises do not even mention govt functioning well. To weaken, we could say that political compromises are not the only thing required for govt to function well i.e. political compromises are not sufficient for govt to function well.


Cognitive scientist: Using the pioneering work of comparative psychologist Gordon Gallup as a model, several studies have investigated animals' capacity for mirror self-recognition (MSR). Most animals exposed to a mirror respond only with social behavior, such as aggression. However, in the case of the great apes, repeated exposure to mirrors leads to self-directed behaviors, such as exploring the inside of the mouth, suggesting that these animals recognize the reflection as an image of self. The implication of these studies is that the great apes have a capacity for self-awareness unique among nonhuman species.

The point is that since apes are displaying MSR, we are implying that they are self aware as if MSR is sufficient for self awareness. We are also saying that other animals are not self aware because they are not displaying MSR.
So MSR is necessary and sufficient for self awareness.

So our assumption is 'no MSR means no self awareness' (and also 'no self awareness means no MSR').
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ALL assumptions are strengtheners but all strengtheners are not assumptions. Only the strengtheners which are actually necessary for the conclusion are assumptions too.
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Thank you VeritasKarishma for helping
i believe i confused sufficient with necessary.
To add to the above and if I got your explanation right.

Clearly, the very insincerity that people decry shows that our government is functioning well.
The meaning of this conclusion is that "insincerity is sufficient for our govt to function well"
Therefore the necessary assumption stood that "Political compromises is sufficient for a good government". This is how we link ?
And the weakener that "Political compromise is not all that is necessary (not...that are necessary = sufficient) for a good govt"

Studies = Repeated exposure - sometimes MSR for apes, repeated exposure ONLY Social behaviour for the rest.
Again, when I say the studies imply that great apes have a capacity for Self Awareness, unique...
the assumption is 1) SOMETIMES MSR is sufficient for Self Awareness.
2) ONLY SOCIAL BEHAVIOUR (NO MSR) is sufficient to say NOT Self Aware.
therefore MSR is necessary too (contra) of the above.
Therefore MSR is sufficient and necessary.
3) i believe the unique keyword then signifies that there is no other sufficient way for Self Awareness.
I guess it adds to necessity of MSR.

Look at the structure of the first argument:

Premise: A is necessary for B.
Conclusion: A means C.

Do you see the problem? The conclusion need to be derivable from the premises but it is not. C is not even mentioned in the premises so how are we concluding about it? This is a major gap.
The assumption needs to link C with A/B.

Also, who said A is sufficient for B? And also who said A/B is sufficient for C? All these are gaps in our argument. To weaken the argument, we can point out any of these. Our correct option says B is not sufficient for C.


Similarly look at structure of second argument:

A (ape) shows MSR.
'Not A' do not show MSR.

Conclusion: Only A is self aware.

Again, self aware is not even mentioned in the premises though we are concluding it. Then the assumption of the argument would link MSR to self awareness.
We are assuming that MSR is sufficient for self awareness (because A is self aware) and also assuming that MSR is necessary for self awareness (because 'not A' is not self aware or in other words, "only A is self aware))
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