Critical Reasoning

Hi experts,

I have been having major trouble in weaken questions. After trying all sorts of strategies stated in different books, although they helped a little, I am still getting them often wrong, So I tried to figure out my own. But I am not sure if this one will work with all sorts of weaken questions.

I will take an example from OG 11 and show how its done and may be someone could point out if this won't work for any case.

Dental researchers recently discovered that tooth-brushes can become contaminated with
bacteria that cause pneumonia and strep throatıThey found that contamination usually Occurs after
toothbrushes have been used for four weeks. For that reason people should replace their
toothbrushes at least once a month

Which of the following if true would most weaken the conclusion above?
(A) The dental researchers could not discover why toothbrush contamination usually
occurred only after toothbrushes had been used for four weeksı
(B) The dental researchers failed to investigate contamination of toothbrushes by viruses
yeasts and other pathogenic microorganisms
(C) The dental researchers found that among people who used toothbrushes contaminated
with bacteria that cause pneumonia and strep throat the incidence of these diseases was no higher
than among people who used uncontaminated toothbrushes
(D) The dental researchers found that people who rinsed their toothbrushes thoroughly in hot
water after each use were as likely to have contaminated toothbrushes as were people who only
rinsed their toothbrushes hurriedly in cold water after each use
(E) The dental researchers found that, after six weeks of useıgreater length of use of a
toothbrush did not correlate with a higher number of bacteria being present

Basically I take the conclusion and add a negation to it and a "therefore" in the front

Therefore, people should not necessarily replace their toothbrushes at least once a month

Then I try applying each choice by adding a "because" and see which ones strengthens the conclusion the most.

In OG , For most of the questions with simple stimulus, this is working 100% correctly. can someone suggest if i can continue using this one. Somehow its easy for me to strengthen a conclusion than weaken.

Most of the times when choices have lots of negations in them, and moreover if the stimulus has lot of negations I get completely confused and mess it up.

If this strategy doesn't seem right, please suggest me one.

I am just 7 weeks away from my D-day and I am still having a low accuracy for CR questions.

I have read the powerscore bible. Inspite of trying to apply the strategies, sometimes the stimulus appears very confusing and even in choices, when they add no's and not's, I end up selecting strengthen answers instead of weaken.

Wonderful response:

https://www.gmathacks.com/critical-reaso ... ships.html

Hi Ludacrispat,

Thanks for the link. While it was really halpful, I am aware of that kind of method. It has been mentioned in the CR Bible. However, i find it difficult to find assumptions in arguments. For easy ones I can but for the difficult ones, its time consuming to figure out the assumption.

I am wondering if the new method I have thought about can be applied to all weaken problem types. Because I see it working in most of the questions in OG. However, I need to know if and why it won't work in any specific cases I am probably not taking into account.

punitkaur wrote:Hi Ludacrispat,

Thanks for the link. While it was really halpful, I am aware of that kind of method. It has been mentioned in the CR Bible. However, i find it difficult to find assumptions in arguments. For easy ones I can but for the difficult ones, its time consuming to figure out the assumption.

I am wondering if the new method I have thought about can be applied to all weaken problem types. Because I see it working in most of the questions in OG. However, I need to know if and why it won't work in any specific cases I am probably not taking into account.

Sounds like you are looking for an algorithmic way to deal with these kind of problems. Honestly, it is very hard to find an algorithm; yes, you can use certain strategies to get rid of some choices.

Sometimes, you need to be clear about what scope is and what it is not.

For instance, an argument talk about beneficial effects of drug on adult males. A weakening choice could be one that talks abt deleterous effects of teh same medicine on 40 year old adults. Here, attacking a subset can weaken the argument.

There are variety of arguments you encounter.

1. Numbers, ratios, weighted averages, percentages.
2. correlation vs causation
3. Analogies
4. others.

Try to learn from wrong choices: i mean, fitting them in a certain pattern. Of course, Powerscore CR bible lists like "shellgame, opposite, irrelevant". But you can go beyond that: in assumption questions, you can get trapped by an inference choice. In a strengthening scenario, you are trapped by a choice that redefines a logical variable/constant in the argument and so on.

punitkaur wrote:Hi experts,

I have been having major trouble in weaken questions. After trying all sorts of strategies stated in different books, although they helped a little, I am still getting them often wrong, So I tried to figure out my own. But I am not sure if this one will work with all sorts of weaken questions.

I will take an example from OG 11 and show how its done and may be someone could point out if this won't work for any case.

Dental researchers recently discovered that tooth-brushes can become contaminated with
bacteria that cause pneumonia and strep throatıThey found that contamination usually Occurs after
toothbrushes have been used for four weeks. For that reason people should replace their
toothbrushes at least once a month

Which of the following if true would most weaken the conclusion above?
(A) The dental researchers could not discover why toothbrush contamination usually
occurred only after toothbrushes had been used for four weeksı
(B) The dental researchers failed to investigate contamination of toothbrushes by viruses
yeasts and other pathogenic microorganisms
(C) The dental researchers found that among people who used toothbrushes contaminated
with bacteria that cause pneumonia and strep throat the incidence of these diseases was no higher
than among people who used uncontaminated toothbrushes
(D) The dental researchers found that people who rinsed their toothbrushes thoroughly in hot
water after each use were as likely to have contaminated toothbrushes as were people who only
rinsed their toothbrushes hurriedly in cold water after each use
(E) The dental researchers found that, after six weeks of useıgreater length of use of a
toothbrush did not correlate with a higher number of bacteria being present

Basically I take the conclusion and add a negation to it and a "therefore" in the front

Therefore, people should not necessarily replace their toothbrushes at least once a month

Then I try applying each choice by adding a "because" and see which ones strengthens the conclusion the most.

In OG , For most of the questions with simple stimulus, this is working 100% correctly. can someone suggest if i can continue using this one. Somehow its easy for me to strengthen a conclusion than weaken.

Most of the times when choices have lots of negations in them, and moreover if the stimulus has lot of negations I get completely confused and mess it up.

If this strategy doesn't seem right, please suggest me one.

I am just 7 weeks away from my D-day and I am still having a low accuracy for CR questions.

I have read the powerscore bible. Inspite of trying to apply the strategies, sometimes the stimulus appears very confusing and even in choices, when they add no's and not's, I end up selecting strengthen answers instead of weaken.

Hi punitkaur,

why do you negate the conclusion before approaching the choices? This seems like an extra step that you don't necessarily have to take. Now your approach is not wrong--you are doing well on the lower-level and moderately difficult problems--but it is not very efficient, and it is a bit confusing when you have the conclusion negated, and when you have "no"s and "nots" in the answer choices.

Better to deal with the argument on its own terms. (If negation comes into the picture, it should be negating a choice--if a negated choice strengthens, then the chioce is a weakener, and if a negated choice weakens, then the choice is a strengthener).

Try to sum up the argument using as few words as possible. Try to get it into one sentence: "Because__, __". Then try to figure out the assumption. Figuring out the assumption is really key in strengthen/weaken questions. Figure out the assumption, and if it is weaken question, look for a choice that directly attacks the assumption. If it is strengthen question, look for a choice that directly backs up the assumption.

This is the best technique, and I am sure you have already read about it. But you should start applying it. Go back to old questions you've already done. Read the argument, cover it up, and see if you can paraphrase it without looking at it. The reason is that figuring out assumption requires you to have effective and concise mental representations of both conclusion and evidence in your head--that taxes your working term memory. So go back to old arguments, and target your working term memory directly--cover up the argument and see if you can paraphrase it. In the beginning, it is okay if you peek at it a bit.

When practicing, don't go to the answer choices before you are done properly and fully analyzing the stimulus. (Use an index card to cover the answer choices up). Know the common patterns (palvarez mentioned the most common ones above), and try to predict an answer.

For example, if the author is trying to argue that X explains phenomenon Y, he is assuming there are no other explanations. To attack this assumption, we will look for a fact that suggests or points to something that could logically be an alternative explanation.

Don't just do bunches of questions, practicing blindly. A good performance is an outcome of a student who focusses on her reasoning process. Spend A LOT of time reviewing. When reviewing wrong answers, remind yourself what your reasoning was that led you to the wrong answer. Try to figure out why the wrong answer is wrong and why the right answer is right--ON YOUR OWN. You're looking for that lightbulb to go off ("ohhhh, THAT'S why it's wrong!"). Only after you have done this should you even think about going to the solution.

This review processs will feel daunting and time-consuming. But it's so worth it (it's better than just doing masses of questions.) This way of reviewing forces you to engage the mode of reasoning that the GMAT wants you to learn. And once you truly understand why a choice is wrong, you will never select a choice that is wrong for the same reason ever again. That is, you will start seeing the patterns.

If you want more elaboration or help, don't hesitate to post again!

Hi Testluv,
thanks a lot for your post. Yes you are right, that strategy works on easy and moderate questions. So as you suggested I will have to try another way now.

Read the stimulus and figure out the assumption. So that means in the exam everytime I read a stimulus, I should have a clear assumption in hand even before looking at the answer choices? Whether it is assumption/weaken or strengthen or all other types?

I thought that a stimulus can have many assumptions, so how can we arrive at a single one before looking at the choices?

punitkaur wrote:Hi Testluv,
thanks a lot for your post. Yes you are right, that strategy works on easy and moderate questions. So as you suggested I will have to try another way now.

Read the stimulus and figure out the assumption. So that means in the exam everytime I read a stimulus, I should have a clear assumption in hand even before looking at the answer choices? Whether it is assumption/weaken or strengthen or all other types?

I thought that a stimulus can have many assumptions, so how can we arrive at a single one before looking at the choices?

You should try to figure out the assumption in assumption, strengthen/weaken, and flaw questions (and also questions that ask you to select a choice that would be most helpful in evaluating the argument). But you should not even think about assumption in inference and resolve the paradox questions--in these questions, you should treat the answer choices as a set of facts.

While it is (theoretically) true that arguments can make more than one assumption, the arguments are almost always written by the test-maker to have one big glaring assumption--ie, the "central" assumption.