The only motives that influence all human actions arise from self-interest. It is clear, therefore, that self-interest is the chief influence on human action.

The reasoning in the argument is fallacious because the argument
(A) denies that an observation that a trait is common to all the events in a pattern can contribute to a causal explanation of the pattern
(B) takes the occurrence of one particular influence on a patterns or classes of events as showing that its influence outweighs any other influence on those events
(C) concludes that a characteristic of pattern or class of events at one time is characteristic of similar patterns or classes of events at all times
(D) concludes that because an influence is the paramount influence on a particular pattern or class of events, that influence is the only influence on the pattern or class of events
(E) undermines its own premise that a particular attribute is present in all instances of a certain pattern or class of events

what a toughie.....took so much time in solving this.....and still unsure....

i pick (D).

Argument says - because of self interest there are quite a few motives evolved. Sometimes these motives affect some human actions and sometimes they affect all human actions. But those motives that affect all human actions are necessarily evolved only from self interest, whereas those affect only some human actions can be evolved from either self interest or something else. Therefore its concluded that self interest is the prime cause of human actions.

problem with the argument is just becuase some motives affect some or all human actions cannot make them the primary cause and this is something we need to look for in the answer

(A) denies that an observation that a trait is common to all the events in a pattern can contribute to a causal explanation of the pattern - trait is not common. self interest doesnt cause every human action. So not correct
(B) takes the occurrence of one particular influence on a patterns or classes of events as showing that its influence outweighs any other influence on those events. This seems to be correct. self interest causes human action does not mean its influence outweighs any other influence on human actions.
(C) concludes that a characteristic of pattern or class of events at one time is characteristic of similar patterns or classes of events at all times. This would be true if we assume that self interest affects all human actions since its affects just one human action. we are not discussing that. not correct
(D) concludes that because an influence is the paramount influence on a particular pattern or class of events, that influence is the only influence on the pattern or class of events . We are not assuming that self interest only affects all actions. We wont to disapprove that self influence is not the only cause. So not correct
(E) undermines its own premise that a particular attribute is present in all instances of a certain pattern or class of events. doesnt help to prove what is expected.

So IMO is B.

The confusion is between B and D . But D is extreme- 'only influence'. So i go for B

B for me too.

Well explained by jinxed and nverma !

Step 1 of the Kaplan Method: Identify the Question Type.

The giveaway is the word 'fallacious', indicating a Flaw question. That means we will need to deconstruct the argument and identify what is the flawed assumption that the author makes. It also means that we need to watch out for tricky, abstract language in the answer choices; many flaw questions describe the error in the author's reasoning using rhetorical terms, rather than specifics.

Step 2: Untangle the stimulus.

This is a straightforward argument. It's only two sentences, and one of them is clearly marked as the conclusion by the keywords 'It is clear, therefore." On our notepad, we should paraphrase that sentence and label it as the conclusion. My notes read something like this:

Conc: Chief infl. on human action = selfishness.

By process of elimination, what's left must be the author's evidence. This sentence is not quite as easy to parse, because of the "only" and the "all", but we still paraphrase it; its basically saying that among the wide variety of motivations for human action, there is only one motivation that factors into all human action: self-interest. I summarized the author's evidence, that the only thing that affects all human actions involve some form of self interest, like so:

Ev: Self interest only universal motivation.

Now that we've identified the written parts of the author's argument, we need to understand what's unwritten. What must be true to bridge the gap between his evidence and his conclusion? When a Kaplan student tries to identify the assumption, he or she knows to look for shifts in terminology or scope between parts of the author's argument. In this case, that first word of our conclusion summary, "chief", is the giveaway. Though the evidence mentions that selfishness affects all human action, the author provides nothing to indicate that self-interest has so much as a significant impact on those actions, let alone the "chief" one! The author leaves a big gap in his argument. So now we know the authors assumption:

Assump: Most widespread influence = most important.

Step 3: Predict the Answer.

This is a Flaw question. On flaw questions, we can expect the answer to explain that the author's assumption is unwarranted. Since the author shifts in scope from being universal to being important, the correct answer will call him out on that missing link. Our prediction for the answer is something like "The author confuses being widespread with being important."

Step 4: Evaluate the answer choices.

There's a lot of tempting answer choices here, but fortunately, we're not concerned. Because we've gone through the Kaplan method, identified the Evidence, Conclusion, and Assumption, and made a prediction about the answer choice, the correct answer should jump out at us. In this case, (B) perfectly matches our predicted answer, and is correct.
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Eli Meyer
Kaplan Teacher
http://www.kaptest.com/GMAT

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