Re: [CR. ] 請教一題CR

看板GMAT (GMAT入學考試)作者danyuchn (Javy)時間7年前 (2017/04/27 13:22)推噓0(0推 0噓 0→)

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※ 引述《Birou (十里春風不如你)》之銘言： : Newspaper editorial: : In an attempt to reduce the crime rate, the governor is getting tough on : criminals and making prison conditions harsher. Part of this effort has been : to deny inmates the access they formerly had to college-level courses. : However, this action is clearly counter to the governor's ultimate goal, : since after being released from prison, inmates who had taken such courses : committed far fewer crimes overall than other inmates. 平常做CR時，建議能夠練習縮減資訊精煉故事：為了減少犯罪率，政府打算不讓囚犯上課。但是這會跟目的牴觸，因為有上課的出獄後再犯次數較低。相信原PO對C的答案思路應該沒什麼問題，做題時應該是A/C在猶豫。所以這裡專門針對A分享一些實戰中邏輯要高分必須注意的陷阱。 : Which of the following is an assumption on which the argument depends? : A. Not being able to take college-level courses while in prison is unlikely : to deter anyone from a crime that he or she might otherwise have committed. 這裡是一個假設題上很常見的陷阱混淆選項。遇到帶兩個否定的因果（如這裡的be unlikely to deter表因果）的時候，要特別注意邏輯上的等價命題：若P則Q只能推到若非Q則非P（注意是逆否），反之亦然——若非Q則非P 只能推回若P則Q。 P->Q 絕對可以推出 Q'->P' 但絕對不會等於 P'->Q' 比如若下過雨(P)則地上會濕(Q)，可以推得「若地上沒濕(Q')，則一定沒下過雨(P')」但絕對不能說「若沒下過雨(P')，則地上一定不會濕(Q')」強化完這個觀念，我們就來看A選項要怎麼推等價命題： Not being able to take college-level courses while in prison (Q') is unlikely to deter (P') anyone from a crime that he or she might otherwise have committed. （Q':若不能上課，則P':不太會停止犯罪）只能推得P->Q：若可以阻止這些人犯罪，則這些人是會有機會受到教育的。（很明顯的主題無關）但不能推得Q->P：若能上課則會停止犯罪。（我猜這就是原po一開始看到A選項會覺得不錯的原因：如果能上課就不會犯罪的話，確認上課必要性，結論不就成立了嗎？）所以請原po以後看到雙重否定因果的時候，多留意就好。不需要每個選項都這樣推，太累了XD Dustin -- Dustin Deng (一戰自修760，AWA 5.5) Dustin/A2GMAT 機經班：http://a2gmat.blogspot.tw/p/blog-page.html GWD實戰模考診斷班：http://a2gmat.blogspot.tw/p/gmat-dustin-1.html GMAT自修資源部落格：http://dustingmat.blogspot.tw A2GMAT線上解題、討論Group：https://www.facebook.com/groups/A2GMAT -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 220.136.39.204 ※ 文章網址: https://www.ptt.cc/bbs/GMAT/M.1493270571.A.4F2.html ※ 編輯: danyuchn (220.136.39.204), 04/27/2017 13:23:41 ※ 編輯: danyuchn (220.136.39.204), 04/27/2017 21:16:23