The argument concludes that the true scientific significance of Walcott's classification of the group of unusual fossils that he discovered is better reflected in a more recent classification than Walcott's own. Why? Because Walcott is a prominent member of the scientific establishment, and therefore, his classifications are "unlikely to have done anything but confirm what established science had already taken to be true." What's the error here? We are making a conclusion on the significance of Walcott's classification based on information about Walcott, and not on his classification. This is an ad hominem flaw. Remember an ad hominem flaw is an attack on the person rather than the argument. The formula for an ad hominem flaw usually goes like this: What X says is wrong because X is [something about X]. We are not discussing the merits of what is said; rather we are discussing the merits of the actual arguer. Here the passage concludes that Walcott's classification is not as scientifically significant as the most recent classification because Walcott is a prominent member of the scientific establishment. This is a classic ad hominem fallacy.
(A) is CORRECT because it clearly describes an ad hominem fallacy. The conclusion is made about a position (i.e. the scientific significance of Walcott's classification) not based on the merit of that position (i.e. whether it is truly more scientifically significant than the most recent classification), but rather based on the position's source (i.e. Walcott).
(B) is incorrect because the argument does not cite two pieces of evidence. The only evidence it uses to base its conclusion on is the fact that Walcott is a prominent member of the scientific establishment. The evidence is neither questionable nor unverifiable.
(C) is incorrect because there are no contradictory premises being used in the argument. Moreover, the second half of this answer choice describes an equivocation flaw. An equivocation flaw occurs when a term with more than one meaning is used in a misleading way. For instance: A feather is light, what is light cannot be dark. Therefore, a feather cannot be dark. The word "light" is equivocated here. Once the word is used to mean weighing little, and once the word is used to mean the opposite of dark. There is no equivocation being made in the passage above.
(D) is incorrect because the claim that the argument attempts to validate (i.e. that the recent classification is more scientifically significant than Walcott's) is not unsupported. The argument also does not deny the truth of the opposite of the claim.
(E) is incorrect because it describes a temporal flaw. A temporal flaw is when something in the past is being applied to something in the present or future, or vice versa. There is no temporal flaw being made in the passage. Moreover, there are no social or political categories that are discussed in the passage.
Hope that helps! Let me know if you have any other questions.
DerekJuly 29, 2014
But how is being called a "prominent member of the scientific establishment" an attack? Wouldn't this be a compliment?
NazAugust 8, 2014
Try not to think of the ad hominem flaw as a literal attack. It merely occurs when an argument is being advocated or criticized with evidence based on the person who made it, rather than on the merits of the actual argument.
Though being a "prominent member of the scientific establishment" is not an attack per say, it is an attack if it is said that Walcott's classification of a group of fossils he discovered is better reflected in a more recent classification because of Walcott's status as a prominent member of the scientific establishment. It's an attack couched in a compliment.
However, regardless of an attack or not, the passage is making its point on the validity of the classifications made by Walcott by using evidence about Walcott rather than evidence about his actual classification.
Hope that clears things up! Please let us know if you have any other questions.
