Example：

　　The death penalty is appropriate for traitors¹ because it is right to execute

　　those who betray their own country and thereby² risk the lives of millions.

　　This argument is circular because “right” means essentially³ the same thing a

　　s “appropriate.” In effect， the writer is saying that the death penalty is a

　　ppropriate because it is appropriate.

　　Shifting The Burden Of Proof

　　It is incumbent⁴ on the writer to provide evidence or support for her positio

　　n. To imply that a position is true merely because no one has disproved it i

　　s to shift the burden of proof to others.

　　Example：

　　Since no one has been able to prove God's existence， there must not be a God

　　……

　　There are two major weaknesses in this argument. First， the fact that God's

　　existence has yet to be proven does not preclude⁵ any future proof of existen

　　ce. Second， if there is a God， one would expect that his existence is indepe

　　ndent of any proof by man.

　　Unwarranted Assumptions

　　The fallacy of unwarranted assumption is committed when the conclusion of an

　　argument is based on a premise⁶ （implicit⁷ or explicit⁸） that is false or unwa

　　rranted. An assumption is unwarranted when it is false——these premises⁹ are u

　　sually suppressed or vaguely¹⁰ written. An assumption is also unwarranted when

　　it is true but does not apply in the given context——these premises are usua

　　lly explicit.

　　Example： （False Dichotomy）

　　Either restrictions¹¹ must be placed on freedom of speech or certain subversiv

　　e elements in society will use it to destroy this country. Since to allow th

　　e latter to occur is unconscionable， we must restrict freedom of speech.

　　The conclusion above is unsound because

　　（A） subversives¹² do not in fact want to destroy the country

　　（B） the author places too much importance on the freedom of speech

　　（C） the author fails to consider an accommodation between the two alternativ

　　es

　　（D） the meaning of “freedom of speech” has not been defined

　　（E） subversives are a true threat to our way of life

The arguer offers two options： either restrict freedom of speech， or lose th

　　e country. He hopes the reader will assume that these are the only options a

　　vailable. This is unwarranted. He does not state how the so-called “subversi

　　ve elements“ would destroy the country， nor for that matter， why they would

　　want to destroy it. There may be a third option that the author did not ment

　　ion； namely， that society may be able to tolerate the “subversives” and it m

　　ay even be improved by the diversity of opinion they offer. The answer is （C

　　）。

　　Appeal To Authority

　　To appeal to authority is to cite an expert's opinion as support for one's o

　　wn opinion. This method of thought is not necessarily fallacious. Clearly， t

　　he reasonableness of the argument depends on the “expertise” of the person b

　　eing cited and whether she is an expert in a field relevant to the argument.

　　Appealing to a doctor's authority on a medical issue， for example， would be

　　reasonable； but if the issue is about dermatology and the doctor is an orth

　　opedist， then the argument would be questionable¹³.

　　Personal Attack

　　In a personal attack （ad hominem）， a person's character is challenged instea

　　d of her opinions.

　　Example：

　　Politician： How can we trust my opponent to be true to the voters？ He isn't

　　true to his wife！

　　This argument is weak because it attacks the opponent's character， not his p

　　ositions. Some people may consider fidelity¹⁴ a prerequisite¹⁵ for public office

　　…… History， however， shows no correlation¹⁶ between fidelity and great politica

　　l leadership.

　　——

　　I would fly you to the moon and back

　　If you'll be if you'll be my baby

　　Got a ticket for a worldswhereswe belong

　　So would you be my baby

上一篇：GMAT考试-Testprep数学精解(11) 下一篇：GMAT考试-Testprep数学精解(13)