邏輯削弱是邏輯單題的基礎(chǔ)。

邏輯削弱的三種方式：找他因，找他果，否假設(shè)。

找他因

weaken?1

In 1998 the United States Department of Transportation received nearly 10,000 consumer complaints about airlines; in 1999 it received over 20,000. Moreover, the number of complaints per 100,000 passengers also more than doubled. In both years the vast majority of complaints concerned flight delays, cancellations, mishandled baggage, and customer service. Clearly, therefore, despite the United States airline industry’s seriousefforts to improve performance in these areas, passenger dissatisfaction with airline service increased significantly in 1999.

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1. Which of the following, if true, most seriously weakens the argument?

D

A. Although the percentage of flights that arrived on time dropped slightly overall, from 77 percent in 1998 to 76 percent in 1999, some United States airlines’ 1999 on-time rate was actually better than their 1998 on-time rate.?準(zhǔn)點率與邏輯框架無關(guān)，就算會導(dǎo)致投訴減少，可是影響不了已成事實的投訴率下降

B. The number of passengers flying on United States airlines was significantly higher in 1999 than in 1998.?那又如何。。證據(jù)已經(jīng)表明投訴率上升，依然是邏輯框架之外

C. Fewer bags per 1,000 passengers flying on United States airlines were lost or delayed in 1999 than in 1998.?同A

D. The appearance in 1999 of many new Internet sites that relay complaints directly to the Department of Transportation has made filing a complaint about airlines much easier for consumers than ever before.?投訴率上升的他因

E. Although the number of consumer complaints increased for every major United States airline in 1999, for some airlines the extent of the increase was substantial, whereas for others it was extremely small.?不是他因也不能動論據(jù)

找他果

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The average temperature of the lobster-rich waters off the coast of Foerkland has been increasing for some years. In warmer water, lobsters grow faster. In particular, lobster larvae take less time to reach the size at which they are no longer vulnerable to predation by young cod, the chief threat to their survival. Consequently, the survival rate of lobster larvae must be going up, and the lobster population in Foerkland’s coastal?waters is bound to increase.

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2. Which of the following, if true, most seriously weakens the argument?

C

A. There are indications that inrecent years the fishing fleet operating off the coast of Foerkland has been taking cod at an unsustainably high rate.?會加強(qiáng)，而且縮小了邏輯框架（只講到cod）

B. The increase in water temperatures of Foerkland has not been as pronounced as the increase in average?soil temperatures?in Foerkland.?加入無關(guān)變量

C. Because of their speeded-up growth, lobsters now get large enough to be legal catch before they reach reproductive maturity.?是他果

D. Even though lobsters grow faster in warmer waters, warmer waters have no effect on the?maximum size?to which a lobster can eventually grow. 同樣是無關(guān)變量，也不需要長最大，夠大就行了

E. Cod are a cold-water species, and the increasing water temperatures have caused a northward shift in Foerkland’s cod population.?不能削弱，反而可能加強(qiáng)，而且同A縮小了邏輯框架

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否假設(shè)

weaken 3 ★★★★

Even after numerous products made with artificial sweeteners became available, sugar consumption per capita continued to rise. Now manufacturers are introducing fat-free versions of various foods that they claim have the taste and texture of the traditional high-fat versions. Even if the manufacturers’ claim is true, given that the availability of sugar-freefoods did not reduce sugar consumption, it is unlikely that the availability of these fat-free foods will reduce fat consumption.

論據(jù)=事實=原因=無糖食品并未降低糖分?jǐn)z入

論點=推測=結(jié)果=脫脂食品不會降低脂肪攝入

基于假設(shè)：脫脂食品跟無糖產(chǎn)品一樣。

出現(xiàn)類比就要小心。

在因果關(guān)系中，要保證“相同主體相同屬性”。

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3. Which of the following, if true, most seriously undermines the argument?

B

A. Several kinds of fat substitute are available to manufacturers, each of which gives a noticeably different taste and texture to products that contain it.?那又如何？搞不好還會加強(qiáng)。其實也動了論據(jù)（原文說味道保持不變）

B. The products made with artificial sweeteners did not taste like products made with sugar.?比如零度雪碧，快樂水不快樂。

C. The foods brought out in sugar-free versions did not generally have reduced levels of fat, but many of the fat-free versions about to be introduced are low in sugar. ?無糖食品不減脂，脫脂食品卻無糖。雜糅信息，沒有證據(jù)

D. People who regularly consume products containing artificial sweeteners are more likely than others to consume fat-free foods.?吃糖和吃脂肪之間的關(guān)系不能隨意建立。吃木糖醇喝元氣森林（赤蘚糖醇）的更喜歡脫脂食品。有可能，因為健康嘛。可是說明不了?脫脂食品不會降低脂肪攝入。

E. Not all foods containing fat can be produced in fat-free versions.?那這個情況糖也是一樣的，只要有一種食品成功就能減少總量。所以不能削弱

檢驗：下面兩題分別用的上面的哪個方式解的：

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There are many structural and thematic similarities between?Piers Plowman?by Langland (1330-1400) and?House of Fame?by Chaucer(1342-1400), two Middle English poems relating dream visions. Some critics have argued that because a number of the shared elements are uncommon in Middle English poetry, and because Langland’s poem probably predates Chaucer’s by afew years, Chaucer was most likely influenced by?Piers Plowman?when writing?Houseof Fame.

?找他因

4. Which of the following, if true, most seriously weakens the critics’ argument?

D

A.?Piers Plowman?is one of Langland’s major works, whereas?House of Fame?is a minor work ofChaucer’s.?與作品重要性無關(guān)

B.?House of Fame?survives in only three manuscript copies,substantially fewer than the number of manuscript copies that exist of?Piers Plowman. ?與多少無關(guān)

C. Because?Piers Plowman?became a well-known work in its day, it is likelythat the similarities between it and?Houseof Fame?were detected by many of the people who read?House of Fame?soon after Chaucer wrote it.?發(fā)不發(fā)現(xiàn)，它就在那里。。

D. Many of the themes and structures of?Piers Plowman?are also found in Latin, Italian, French works with which Chaucer could well have been familiar.?又不是PP專屬的

E. There is no evidence thatChaucer and Langland ever met or that they corresponded with each other aboutliterary topics.?影響非得認(rèn)識么。。。

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weaken 5

The Great Sphinx is a huge statue in Egypt that has a lion’s body with a man’s head. The face of the Sphinx has long been claimed to be that of pharaoh Khafre, who lived around 2600 B.C., but it cannot be: erosion patterns recently discovered on the lion’s legs can only have been caused by heavy rains, and the Sahara has not had heavy rains in over 10,000 years.

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論點=推測=原因=臉不可能是2600BC哈夫拉的（因為臉很新）=老早就建好了

論據(jù)=事實=結(jié)果=腿部有10000年前的特征（很老）

基于假設(shè)：整體是一起修的。原理同3

5. Which of the following, if true, most seriously weakens the argument?

E

A. The face of the Sphinx bears a resemblance to the faces on certain stylized statues dating from both before and after the reign of Khafre. ?引了無關(guān)，不在邏輯框架內(nèi)討論。

B. Other erosion patterns that appear on the body of the Sphinx are of a sort that could be caused by?wind and sand?alone 引了無關(guān)，先給我解釋雨的事兒，別整那些沒用的

C. Other than the Sphinx, there are no surviving sculptures that have been claimed to portray the face of Khafre. 他非得要有個什么雕塑留下來么。。

D. In the last 10,000 years the climate of Egypt has been so dry that even rains that are not heavy have been extremely infrequent. 就算有雨也不夠大，導(dǎo)致不了erosion. 更加說明了侵蝕痕跡年份很早，反而會加強(qiáng)

E. The face of the Sphinx is small relative to the rest of the head, indicating that the face may have been recarved long after the Sphinx was built. 臉是新的