GMAT Verbal対策 例題から見るCRの取組み方 解説とポイント

さて、前回の記事に続き、今日はGMATのCritical Reasoning(CR)の問題の解き方の解説を行う。

前回からの復習

前回の記事では、CRのベーシックな構造を解説した。

全ての文章は、Argumentとも呼ばれるConclusionがあり、これはメインテーマで著者の主張である。

Conclusionには、それをサポートするPremiseが必要。Premiseは、Conclusionにツッコミどころがあったとしても、いつでも正しい。

PremiseとConclusionの間にある、事実から結論への飛躍をGapと呼ぶ。Gapが見つかれば、半分の仕事は終わったようなもの。では、どうやってGapを見つけたら良いのだろうか?

 

時々、ConclusionはPremiseで述べられていない情報を含む。そして、Conclusionでは言葉の使い方が変わる。Conclusionでは、より強い言葉が使われる。新しい項目が追加される。Premiseにはなかった、数の情報や修飾語が足される。

 

Gapを見つけるために、Conclusionに含まれる言葉と言葉の変化に気をつけよう。

some、many、most、all、none等の数字を表す表現には注意しよう。

might、may、can、could、possible、sometimes等の修飾語に注意しよう。

everyone、must、never、each、no one、always等の言い切りの表現には注意しよう。

strongest、fastest、best、only等の強い言葉にも注意が必要だ。

 

Palash
ここまでは前回の重要ポイントのおさらい。詳しくは前回の記事を参考にしてほしい。

 

PremiseとConclusionを例題で理解する

以下の文章から、PremiseとConclusionを探してみよう。

Archeologists have discovered three sites showing conclusive evidence for the mastery of fire in Tanzania, from a period slightly after the time that Homo habilis was present in Africa.  These sites clearly were founded by Homo erectus, the descendent species of Homo habilis that migrated north, out of Africa and into Asia. Homo erectus was known to have mastered fire, from ample evidence at sites in Asia.  There is no reason to attribute mastery of fire to Homo ergaster, the descendent species of Homo habilisthat remained in Africa.

意訳

考古学者は、Homo habilisというアフリカに存在していた種族の少し後に、タンザニアで火が使われていたという証拠を3つの場所で発見した。これらの場所は、Homo erectusによって作られた。Homo erectusは、アフリカからアジアに移住したHomo habilisの子孫で、アジアにおいて、たくさんの火を使っていたという証拠を残している。したがって、Homo habilisの子孫であり、アフリカに残っていたHomo ergasterが火を使っていたと考えるのはおかしい。

 

Palash
さて、これは前回の記事であった、2つめの練習問題だ。PremiseとConclusionを見つけることはできただろうか?

 

本文の理解

さて、現時点において、時間が足りないとか、答えを間違えた、ということは全く気にしなくて良い。本文が難しくて理解が難しければ、簡単な言葉に置き換えて、紙に簡単にメモをするのも良いだろう。

 

本文から重要な箇所を抜き出そう。

evidence of mastery of fire in Tanzania. Erectus and Ergaster are both descendants of habilis. Erectus moved from Africa to Asia. Ergaster stayed back in Africa. There is evidence of fire in Asia belonging to erectus. Evidence in Tanzania must belong to erectus. Ergaster must not have mastered fire.

gmat例題

 

次に、PremiseとConculusionを探そう。Premiseは証拠、事実又は統計で、どんな時でも正になることを忘れないこと。Conclusionは意見、提案やレコメンデーションであることが多い。

 

Premise

では、どのパッセージが証拠や事実を提供しているだろうか?

Archeologists have discovered three sites showing conclusive evidence for the mastery of fire in Tanzania, from a period slightly after the time that Homo habilis was present in Africa.  Homo erectus was known to have mastered fire, from ample evidence at sites in Asia. 

文中の、evidenceという言葉は、Premisesを示唆している。この文章はPremisesだ。

 

Conclusion

では、このPremisesを使って、著者はどんなことを主張しようとしているのだろうか?

These sites clearly were founded by Homo erectus, the descendent species of Homo habilis that migrated north, out of Africa and into Asia. There is no reason to attribute mastery of fire to Homo ergaster, the descendent species of Homo habilis that remained in Africa.

これらの2つの文章は、意見か主張のように聞こえる。また、clearlyは、conclusionを示唆している。そのため、これらはConclusionだ。Why Testを使ってPremiseとConclusionが正しいかどうか確かめよう。

 

Why Test

“The evidence of fire in Africa must belong to erectus and not to ergaster because the evidence of fire in Asia belongs to erectus?”

OR

“the evidence of fire in Asia belongs to erectus because the evidence of fire in Africa must belong to erectus and not to ergaster?”

 

2つめの文章は意味をなさない。僕たちのConclusionとPremiseは正しい。

ここでのポイントは、PremiseとConclusionを正しく見つけることができたとしてもConclusinonに説得力があるかどうかはわからないということ。

 

Gap

次に、Gapを見つける。Gapは、事実から結論への飛躍、PremiseからConclusionを出すために漏れている情報だったね。

 

本文のPremisetとConclusionを短くすると、アジアにある火の証拠はerectusのものだから、アフリカにある火の証拠はerectusのもので、ergasterのものであると考える理由はない。

このConclusionに説得力はあるだろうか?

 

他の例で考えてみよう。

もし、君の友達が、先週近所の人の睡眠を妨害したとして、昨日の睡眠を妨害したのも、絶対にその友達のせいだろうか?君や、他の人が犯人ということはないだろうか?

だから、僕たちは「確実に友達が犯人だ」とか、「他に誰かがやったと信じる理由はない」ということは言えないよね。

 

このConclusionの不確実性(あるいは確実性)を、PremiseとConclusionの間にあるGapと理解してほしい。Conclusionを支える十分なデータがないのにも関わらず、思い切った結論を出している。

 

実践問題

GMATのCRにはたくさんのタイプの問題がある。ここでは、1つのタイプの問題を解いてみよう。

例題1

Archeologists have discovered three sites showing conclusive evidence for the mastery of fire in Tanzania, from a period slightly after the time that Homo habilis was present in Africa.  These sites clearly were founded by Homo erectus, the descendent species of Homo habilis that migrated north, out of Africa and into Asia. Homo erectus was known to have mastered fire, from ample evidence at sites in Asia.  There is no reason to attribute mastery of fire to Homo ergaster, the descendent species of Homo habilis that remained in Africa.

Which of the following is an assumption on which the argument depends?

 

消去法を使ってこの問題を解いてみよう。

(A)の選択肢は、Homo erectusがアフリカからアジアに移住する前に、タンザニアにも住んでいたと言っている。アフリカの火の証拠はタンザニアで発見されたから、Homo erectusはタンザニアに住んでいた、というのは筋が通っている。もし、Homo erectusがタンザニアにいないのであれば、誰かほかの種族がタンザニアで火を使っていたのかもしれない。(A)は良さそうだ。

 

ここで、直感的に(A)を選んで次に進みたくなるかもしれない。けど、それは絶対にやってはダメだ。ほかにもっと良い答えが見つかるかもしれない

この答えは保留にしておいて、他の選択肢を見てみよう。

 

(B)は、移住のプレッシャーがErectusに火の使い方を学ぶモチベーションを与えたと言っている。もしかしたら、そうかもしれないね。けど、この選択肢は火がタンザニアで作られたかどうかは言及していない。Erectusはアフリカを出てから火を学んだのかもしれないし、タンザニアで作られた火は、誰かほかの種族のものの可能性もあるよね?(A)と(B)を比べると、(A)の方が理にかなっている。(B)を削除しよう。

 

(C)は、EragasterとEractusがどれだけ火から利益を得ていたかどうかを比較している。もしかしたら、Erectusは火からたくさん便益を得ていたかもしれないけど、これはタンザニアの火がErectusによって作られたということは証明できないし、誰かほかの種族によってタンザニアで火が作られたのかもしれない。(C)を削除しよう。

 

(D)は、Ergasterが全ての知識を(火を使うことができない)Habilisから受け継いだと言っている。Erectusも、Ergaster同様Habilisが進化した種族であり、Erectusも(火を使うことができない)Habilisから全ての知識を受け継いでいるのではないだろうか?Erectusが火を使えるのであれば、Ergasterも火が使えるのではないだろうか?(D)を削除しよう。

 

(E)は魅力的に見えるかもしれないが、この文章はErgasterがTanzaniaには住んでいなかったということを言っている。気をつけてほしいのは、Erectusについては何も言及していないことだ。Ergasterはタンザニアで火を使っていなかったかもしれないが、Erectusも同様にタンザニアで火を使っておらず、他のほかの種族が火の証拠を残したのかもしれない。(E)は削除しよう。

 

(B)、(C)、(D)、(E)を削除して、残った(A)を安心して選ぶことができた。

 

例題2

下記の例題を解いてみよう。

Because no employee wants to be associated with bad news in the eyes of a superior, information about serious problems at lower levels is progressively softened and distorted as it goes up each step in the management hierarchy. The chief executive is, therefore, less well informed about problems at lower levels than are his or her subordinates at those levels.

The conclusion drawn above is based on the assumption that:

 

Palash
解説は次回行う。また、次回はCRで使える他のツールも見ていこう。
Palash
もし、何か質問があれば、遠慮なくgmat.v35@gmail.comまで連絡してほしい。

 

練習の時は時間よりも理解を重視しろ?

ねこ君
CRって相当むずい・・。かなり時間はかかったけど、コンセプトは理解できたかな。PremiseとConclusionを探すのがCRの仕事なんだね。
ねこ君
一個質問がある、問題を解く時間なんだけど、この戦略を、1問2分以下で解かなければいけない、本番の限られた時間の中で、使える自信が全くないんだけど・・。
Palash
いい質問だね。たくさんの生徒は同じような疑問を持っているよ。
Palash
GMATの準備をするとき、最初は内容を理解することから始めよう。ゼロから学ぶ、子供みたいに始めよう。新しい言語をゼロから学ぶように考えよう。僕たちはA、B、Cから初めて、だんだんレベルを上げていく。A、B、Cを学んでいる時、誰も詩を書きたいとか、新聞記者になりたいとは考えないよね?
Palash
今は、戦略を学ぶことと、新しい方法で、問題を解くことに全力を尽くそう。子供のように、新しいプロセスを学ぶことを楽しもう。練習を通じて、断片的だった知識は、最終的に使える知識・経験になるんだ。戦略を使えるようにすれば、もっと短時間で解けるようになるのが普通。
Palash
学ぶプロセスを楽しむことも忘れないで。楽しむことが、学ぶ効率を最もスピードアップする一番簡単な方法だからね。

 

 

English Version

Reviews from the Previous Article

In the previous article, we discussed the structure of CR. We spoke about and the conclusion. Every passage, also called as argument, has a central theme, or message or claim. It is called the conclusion. The conclusion uses the premises to support itself. Premises are always correct and cannot be questioned or modified whereas the conclusion is uncertain. The gap is the missing link between the premises and conclusion. The ‘jump’ or the ‘leap of faith’ that the argument makes to reach the conclusion based on the premises is the gap. Being aware of the gap is half the job done.

How to identify gap?

Sometimes the conclusion contains things not mentioned in premise. There can be shifts in language. The conclusion could sound more strong or aggressive than the premise. There might be new items in the conclusion that were not present in the premise. The conclusion might contain conditions or qualifiers not mentioned in premise. In short, pay close attention to language and the minor changes in language. These minor changes can help you find the gap.

Give attention to quantity words such as some, many, most, all and none. Pay attention to qualifiers such as might, may, can, could, possible and sometimes. Give attention to absolute language such as everyone, must, never, each, no one and always. Pay attention to superlative such as strongest, fastest, best and only.

 

Example Question

Let us examine the 2nd practice example from the previous article:

Example question

Archeologists have discovered three sites showing conclusive evidence for the mastery of fire in Tanzania, from a period slightly after the time that Homo habilis was present in Africa.  These sites clearly were founded by Homo erectus, the descendent species of Homo habilis that migrated north, out of Africa and into Asia. Homo erectus was known to have mastered fire, from ample evidence at sites in Asia.  There is no reason to attribute mastery of fire to Homo ergaster, the descendent species of Homo habilis that remained in Africa.

 

For now we will learn like a child. We will start simple. No need to worry about time or results. No need to worry at all. We will use simple terms and if needed, we must write on a piece of paper small notes or draw. These are the important points- evidence of mastery of fire in Tanzania. Erectus and Ergaster are both descendants of habilis. Erectus moved from Africa to Asia. Ergaster stayed back in Africa. There is evidence of fire in Asia belonging to erectus. Evidence in Tanzania must belong to erectus. Ergaster must not have mastered fire.

 

gmat例題

 

Let us identify premise and conclusion. Remember premise is usually evidence, fact or statistic and has to be true. Conclusion is usually opinion, suggestion or recommendation. Which part of the passage provides evidence or support?

Archeologists have discovered three sites showing conclusive evidence for the mastery of fire in Tanzania, from a period slightly after the time that Homo habilis was present in Africa.  Homo erectus was known to have mastered fire, from ample evidence at sites in Asia.

The word ‘evidence’ indicates premises. Hence these sentences are premises.

 

Based on these premises what is the passage trying to claim?

These sites clearly were founded by Homo erectus, the descendent species of Homo habilis that migrated north, out of Africa and into Asia. There is no reason to attribute mastery of fire to Homo ergaster, the descendent species of Homo habilis that remained in Africa.

These two sentences sound like an opinion or claim. Also the word ‘clearly’ indicates conclusion. Hence these sentences must be conclusion.

 

Let us do why test to confirm our result.

“The evidence of fire in Africa must belong to erectus and not to ergaster because the evidence of fire in Asia belongs to erectus?” OR “the evidence of fire in Asia belongs to erectus because the evidence of fire in Africa must belong to erectus and not to ergaster?”

The second question does not make much sense. Hence, our conclusion and premise is correct. Take note that though we have identified the premises and conclusion of the passage correctly, we do not know whether the conclusion is valid or not. It might be or it might not be.

 

Let us continue with this example and try to find the gap. Gap is the missing part or the jump from premise to conclusion. There appears to be a shift in language in the conclusion. It sounds unnecessarily strong and aggressive. There is evidence in Asia for erectus hence the evidence in Africa CLEARLY belongs to erectus and there is NO REASON to believe that it could belong to ergaster.

Consider this case. If your friend was caught disturbing your old neighbor’s afternoon nap last week, it must be him again yesterday and there is no reason to believe it could be you or someone else. Maybe it was him again. But we do not know for sure. Hence we cannot declare that it was CLEARLY him and there is NO REASON to believe that it could be someone else. The certainty in the conclusion here and in the passage is what we mean by gap. There is not enough data but it made a jump.

 

Practice Questions

Question1

There are many types of questions on CR. Let us solve one type now. We will consider the same example.

Archeologists have discovered three sites showing conclusive evidence for the mastery of fire in Tanzania, from a period slightly after the time that Homo habilis was present in Africa.  These sites clearly were founded by Homo erectus, the descendent species of Homo habilis that migrated north, out of Africa and into Asia. Homo erectus was known to have mastered fire, from ample evidence at sites in Asia.  There is no reason to attribute mastery of fire to Homo ergaster, the descendent species of Homo habilis that remained in Africa.

Which of the following is an assumption on which the argument depends?

(A) Before their migration, Homo erectus occupied African territory as far south as Tanzania.
(B) The strain of migration provided the selective pressure motivating Homo erectus‘ mastery  of fire.
(C) Homo ergaster would not have derived as much benefit from the mastery of fire as did Homo erectus.
(D) Homo ergaster inherited all cultural knowledge from Homo habilis, a species that did not have mastery of fire.
(E) Homo ergaster did not occupy regions as far south as Tanzania until well after the time of these three sites.

Let us do POE.

(A) says that before they left Africa for Asia, they were present in Tanzania as well. Since the African evidence is from Tanzania it makes sense that they should have been living in Tanzania. If not, someone else must have created fire in Tanzania.

Our normal instincts would make us select it as correct and move on to next question. DO NOT DO IT ON GMAT SINCE YOU CAN HAVE BETTER ANSWERS. We will keep this answer and examine all the rest.

(B) says that the pressure of migration drove erectus to master fire. Maybe it did. But it does not say anything about who made fire in Tanzania. Hence it is incorrect. You can also see that (A) makes better sense than (B) hence we can eliminate (B).

(C) compares the benefit of fire to ergaster and erectus. Maybe erectus would have benefitted more but does not prove that they alone made fire in Tanzania and nobody else. Eliminate (C).

(D) says that ergaster inherited all cultural knowledge from habilis, who did not know fire. Since erectus also evolved from habilis they also must have inherited all cultural knowledge from habilis yet they mastered fire. If erectus could, why could ergaster not do so? Eliminate (D).

(E) is tempting because it says ergaster did not live in Tanzania. Be careful because it says nothing about erectus. Maybe ergaster did not master fire in Tanzania. But maybe erectus di not either and somebody else did. Hence eliminate (E).

After eliminating (B), (C), (D) and (E) we can safely select (A).

 

Question2

Kindly consider the following example for practice.

Because no employee wants to be associated with bad news in the eyes of a superior, information about serious problems at lower levels is progressively softened and distorted as it goes up each step in the management hierarchy. The chief executive is, therefore, less well informed about problems at lower levels than are his or her subordinates at those levels.

 

The conclusion drawn above is based on the assumption that:

(A) problems should be solved at the level in the management hierarchy at which they occur

(B) employees should be rewarded for accurately reporting problems to their superiors

(C) problem-solving ability is more important at higher levels than it is at lower levels of the management hierarchy

(D) chief executives obtain information about problems at lower levels from no source other than their subordinates

(E) some employees are more concerned about truth than about the way they are perceived by their superiors

In the next article we will discuss the solution and another valuable tool in CR.

 

MESSAGE

Question: It took me sometime but eventually I understood it. I feel it will be helpful. My question is regarding the timing the questions. I am not sure how to apply the strategies in such limited time.

Palash: That is a common doubt for many students. GMAT is a completely different kind of exam. We are beginning to understand. It is better we begin like children. Think of it as learning a new language. We start with A,B,C and so on. When we are learning the alphabets there is no point thinking of composing poetry or writing newspaper columns.

At this point we must give all our attention to learning the strategies and the new ways of solving questions. Be carefree like a child. Focus and enjoy the learning process. With practice, pieces of the puzzle will start falling in place. Naturally timing will improve as well. Of course enjoying the process makes a huge difference. It is the easiest way to speeden up our learning rate.

 

にゃんこ先生
質問、要望、ツッコミ、おすすめ勉強法、なんでも遠慮せずにコメントしてね。閲覧者同士でのコミュニケーションも大歓迎だよ。
にゃんこ先生
読んでくれてありがと。FacebookTwitterから、最新情報を受け取る事が可能だよ。シェアもよろしくね。
 

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