Weakening Questions

ICantThinkofaDisplayName

Can anyone help me to understand whether weakening questions are (1) only supposed to address the logical relationship between the premise and conclusion, and (2) are subject to general flaw reasoning. I thought so, but two questions have been throwing me for a loop, both from Kim's The LSAT Trainer. They are:

(1)

"Professor Watkins just received a significant raise, and now Professor Jenson has requested one too. However, Professor Watkins was only eligible to get a raise if she received tenure; she recently was awarded tenure, and was given the raise. Professor Jansen has no desire to get tenure, is not on track to get tenure, and will not get tenure. So, Professor Jenson's request will likely be denied."

Apparently, the answer that "Professor Jenson is well known for the work he does in his field, and the school is known to give raises in order to retain professors who are significant in the areas in which they work" is a weakening response. I don't understand how this can be, considering it has no logical bearing on the connections between the premise supports or conclusion. If it simply said "The university plans to give him tenure regardless," would that be an appropriate weakening response? The same book warns that "attractive wrong choices strengthen or weaken the point but not the reasoning." Is this possible because the answer here provides its own reasoning (Jenson -> well known and well known -> raise)? Otherwise I cannot make sense of it.

(2)

"Medical Expert: For the past six months, we have been keeping statistics on surgery time for prostatectomies performed through traditional means, and through a new procedure that uses robotics. The study revealed that the surgeries using robotics took a average of forty-three minutes, whereas traditional surgeries took an average of over seventy minutes. The study involved sufficient enough mix of doctors and hospitals to guarantee that personal surgical skills and access to other types of equipment were not a factor in the study outcome. Therefore, we can conclude that in general it is faster to perform prostatectomies robotically than it is to perform them using traditional means."

Apparently, the answer "For the most simple prostatectomies, traditional surgeries take, on average, less time than robotic surgery" is a weakening response. I thought it was irrelevant, given this is clearly a part to whole flaw, but the book says that, because the fundamental flaw is that the stimulus ignores that different types of surgeries may take different time and that may be why the robot is faster (it could have just been getting faster surgeries), that this weakens the conclusion. I am confused, as it could be that some fraction of surgeries is faster without robots, but that does nothing to weaken the conclusion that /in general/ surgeries are faster robotically. Do very general reasoning flaws not apply when one is saying that a response weakens a conclusion? Is the statement "Most cars are red" weakened by the response "but my car is blue"?

To note, I don't believe these passages come from PrepTests, they were just made for the book. Please let me know what you think!

PriYanksya

1. There's a conditional relationship established in the premises, but it's also a highly specific one that applies only to one professor: if W tenure --> W eligible for raise, but the premises don't say that this is the only way to get a raise. The rationale for the AC to weaken is that it attacks an underlying assumption: that the conditional relationship is the only way to get to the necessary condition outcome, and that it also applies to the other professor. But that's not true, just because you negate the sufficient condition doesn't mean the necessary condition can't happen any other way. The AC shows an alternate way to get the outcome of receiving a raise. (This is also a common flaw. Negating sufficient doesn't allow you to make any conclusions and same with affirming necessary).

2. I think this question and AC shows why it's difficult to learn much from third party sources making up examples. This doesn't seem like a reasonable answer choice to me. This book example is trying to show that such a general conclusion may not apply across the board to all surgery types, a whole to part flaw as you mentioned. But I completely understand your confusion; the AC they say is correct wouldn't actually weaken the support structure in my reading of the stimulus because they discuss average surgery times in the premises and make a reasonable conclusion about the general speed of this observed class of surgeries. The fact that simple surgeries are faster is already factored into the calculation of the average speed of this type of surgery, so adding that information is not weakening, just explains that within the superset, a subset may buck the general trend. I agree with you that this is not a weakener at all.

Now I remember why I stopped reading the LSAT trainer...great info about structure, but the examples were not airtight like the official ones usually are. Someone else please chime in if there's something about #2 that makes the AC weaken!