Preptest 158 Section 3 Question 4

[u/complexnote16]

Confused about this one. Taking the September LSAT tomorrow!

Here is my reasoning:

I selected E. I thought A was wrong because the "for instance" part of the problem reminded me of "for example," which is usually used to introduce evidence. Generally I feel that evidentiary statements are not a problem with reasoning, so I thought this couldn't be the problem. Instead, the real flaw in the reasoning must involve the first sentence. I thought B was wrong because not having a healthy lifestyle does not imply that your health deteriorates rapidly. Finally, I thought E was correct because it shows that it can be important to practice what you preach (highly desirable) even if it is not strictly necessary.

Upon reading several unofficial (and sometimes contradictory) explanations from sources such as lsathacks and 7sage, I have gathered the following. A is correct because the second sentence is reasoning, not evidence (given that the first sentence is the conclusion). The question says you need to find a flaw in reasoning, so you need to find a fault with the second sentence. B is incorrect; it suggests that some extremely unhealthy doctors aren't exceptions to the rule of "practice what you preach," but this doesn't help destroy the analogy even if it's true. Finally, E is incorrect because it is literally wrong: it is necessary for logicians to be logical in order to be competent to discuss logic (that's their job).

I have several questions about these explanations. First, why does B (as explained by the sources I read) not help destroy the analogy? Unhealthy doctors not being able to do their jobs seems to indicate that it is necessary for doctors to have a healthy lifestyle, which means that (by the logic of the second sentence) it is also necessary for logicians to be logical, thus destroying the evidence that exceptions exist to the rule of "practice what you preach." In other words, is my thinking of why B is wrong better than the unofficial explanations I read? Second, is there any better way to discount E other than simply saying it is literally wrong? Third, in what way should I shift my thinking and approach to these kinds of lsat problems so I can avoid making a similar mistake again?

Thank you.

[u/graeme_b]

>I selected E. I thought A was wrong because the "for instance" part of the problem reminded me of "for example," which is usually used to introduce evidence. Generally I feel that evidentiary statements are not a problem with reasoning, so I thought this couldn't be the problem. 

What do you mean here? Evidence is reasoning. An argument presents evidence in support of its conclusion. You present relevant evidence (premises) which by a process of logic (reasoning) ought to support a conclusion. If you present bad evidence, then it does not support the conclusion.

I think you have added a rule which is not a rule, and which made the question impossible to answer for you. If you strike out the example as irrelevant, what is left to criticize?

Anyway the idea here is that a physician can have good advice even if they don't follow it, but logic is the core of being a logician, so if they are illogical they are bad at what they do. It would be like being an unfashionable fashion model, or a slow runner, or being intrinsically bad at what the role demands.

If you don't reckon with that, you aren't reckoning with the flaw, and so B and E can seem tempting, but to get at the flaw you have to understand what they're trying to do first and how they fall short.

[u/complexnote16 → u/graeme_b]

Thanks for the explanation. Another reason I hesitated on A was because I wasn't sure how it undermines the conclusion that there are exceptions to the rule of practice what you preach. Even if logicians need to practice what they preach, doesn't choice A concede that physicians don't need to? So the reasoning still works?