無論是GRE還是GMAT寫作評分都很看重論據(jù)是否對觀點(diǎn)進(jìn)行了有效支持，因此選擇合適的論據(jù)至關(guān)重要。通常來說，選擇論據(jù)有如下幾個思路：一是例證法（包括名人偉人的例子，無名小人物的例子，有名有姓小人物的例子，親身經(jīng)歷等）；二是引經(jīng)據(jù)典法（引用圣經(jīng)、希臘神話、羅馬神話等）；三是引用權(quán)威法（導(dǎo)師、教授或在某一領(lǐng)域有特長的人）；四是引用數(shù)據(jù)；五是類比法。

美嘉導(dǎo)師就在這里想就類比在寫作中的應(yīng)用進(jìn)行一下分析：

一、類比在ISSUE中的應(yīng)用。

ISSUE是立論文，也就是說，我們需要用理由或例子去支持自己的觀點(diǎn)。在英語中有個單詞叫comparable，直譯的話是可比較的，其實(shí)它等同于similar（相似的）這個單詞，因?yàn)樵谖鞣轿幕?，只有相似的東西才具有可比較性。因此相似性也就成為了整個類比關(guān)系的前提和基礎(chǔ)。

美嘉導(dǎo)師認(rèn)為，類比（Analogy）在上述提到的五種論據(jù)方法中是有邏輯性的，使用得當(dāng)可以省力又出彩地證明觀點(diǎn)。它有點(diǎn)像中學(xué)時代所學(xué)的幾何題，解題的關(guān)鍵不在論證的過程，而是添加一條輔助線。只要找到合適的輔助線，論證就是水到渠成的事了。當(dāng)我們想論證一個抽象復(fù)雜的命題A——B 時，我們可以選擇一個具體形象并且不需要證明的——D來作為輔助線，然后就把原本復(fù)雜的A——B的論證過程替代為論述AB和CD之間的相似性就可以了。這里需要指出的是，所謂具體形象且不需要證明的CD其實(shí)指的就是事實(shí)或常識。所以類比關(guān)系建立的難點(diǎn)就在與選擇合適的CD。我們來看個例子。

The Negro has callus growing on his soul and it’s getting harder and harder to hurt him there. That’s simple law of nature. Like a callus on the foot in a shoe that’s too tight. The foot is nature’s and that shoe was put on by man. The tight shoe will pinch your foot and make you holler and scream. But sooner or later， if you don’t take the shoe off， a callus will form on the foot and begin to wear out the shoe.

It’s the same with the Negro in America. That shoe—the white man’s system—has pinched and rubbed and squeezed his soul until it almost destroyed him. But it didn’t. And now a callus has formed on his soul， and unless that system is adjusted to fit him， too， that callus is going to wear out that system.

很顯然在這段文字中，作者想證明的是全文第二段的后一句話：And now a callus has formed on his soul， and unless that system is adjusted to fit him， too， that callus is going to wear out that system.（現(xiàn)在黑人的靈魂中已經(jīng)產(chǎn)生了老繭，除非白人的統(tǒng)治體系能調(diào)整以適合他們，否則老繭將使這個體系土崩瓦解。）簡而言之，就是黑人終將沖破白人統(tǒng)治。

美嘉導(dǎo)師提示：黑人反抗白人統(tǒng)治獲得解放這無疑是個非常抽象復(fù)雜的命題。采用一般的例證法，學(xué)生們都不約而同能想馬丁.路德.金。且不管例子雷同與否，事實(shí)上，很少有人能真正清楚又準(zhǔn)確地寫出馬丁.路德.金的具體事跡來證明這個觀點(diǎn)。甚至還有學(xué)生會想到曼德拉或奧巴馬來證明，實(shí)在有失偏頗。

現(xiàn)在我們再來看上面這段文字。作者很巧妙地找了CD，即 foot（nature）——shoe（ put on by man）之間的關(guān)系。 鞋子小了，腳穿著會疼，如果不及時脫掉或調(diào)整，腳上會產(chǎn)生老繭。如果鞋子繼續(xù)對腳進(jìn)行禁錮，那么總有一天，腳會把鞋子穿破。這是一個再平常不過的道理，不需要再花時間進(jìn)行論證，括號里的就是AB和CD間的相似性，輕松論證了這個復(fù)雜的命題，這就是類比的魅力。

下面再給大家一段文字來體會類比的妙用。

“It is unrealistic to expect individual nations to make， independently， the sacrifices necessary to conserve energy. International leadership and worldwide cooperation are essential if we expect to protect the world’s energy resources for future generations.”

Another reason why an international effort is required is that other problems of an international nature have also required global cooperation. For example， has each nation independently recognized the folly of nuclear weapons proliferation and voluntarily disarmed? No. Only by way of an international effort， based largely on coercion of strong leaders against detractors， along with an appeal to self-interest， have we made some progress. By the same