## #6 - Chronic fatigue syndrome is characterized by prolonged

nmgee
LSAT Apprentice

Posts: 15
Joined: Fri Jun 01, 2018 2:23 pm
Points: 15

Hi,

I selected the correct answer to this problem (B), but did so by process of elimination because I did not see a stronger answer than B. Could you please explain why B is correct? I'm having trouble understanding why the "more likely" in answer choice B is a necessary assumption to the conclusion that the "syndrome is, in fact, caused by one virus". If it is only "more likely" to combat one virus than multiple, why is it considered evidence that the syndrome is indeed caused by one virus?
Alex Bodaken
PowerScore Staff

Posts: 136
Joined: Wed Feb 21, 2018 10:18 am
Points: 135

nmgee,

Thanks for the question. Let me see if I can help. This is a question where the Assumption Negation Technique may be useful - as a reminder, this is where we logically negate an answer choice and see if it weakens the conclusion; if it does, it is the correct answer.

Answer choice (B) reads: "It is more likely that the new drug counteracts one virus than that it counteracts several viruses." The logical negation of this would read "It is NOT more likely that the new drug counteracts one virus than that it counteracts several viruses." Okay, so does this weaken the conclusion? It does, and here's how: if it isn't more likely that the new drug counteracts one virus as opposed to several, than we have no way of knowing if all of the symptoms (fatigue, pain, neurological symptoms) have been reduced because the drug is reacting to one virus that causes all of those symptoms or to multiple viruses causing these symptoms. This would weaken the conclusion. If, by contrast, it is more likely that the new drug counteracts one virus than that it counteracts several, then we have good evidence to conclude that the symptoms are being caused by one virus, since the virus is lessening all of them and yet is likely only responding to one virus.

Hope that helps!
Alex
whardy21