PS's Justify the Conclusion - 'Mechanistic Approach'

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MrAdams
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PS's Justify the Conclusion - 'Mechanistic Approach'

Postby MrAdams » Mon Nov 22, 2010 11:39 am

I will be honest I have only just readdressed this approach as I am running through the LRBible again and did not remember to use it until now. Thing is, I have already done about 20 pt's and I have only 13 left before December (46-58) so I am not aware as to how useful it is in practice. PS notes that this approach works for 'the vast majority' of justify questions.

Does anyone else use this approach and can verify that it does indeed work for most justify questions? This could be an amazing time saver if you can judge the correct answer by just skimming for both the rogue elements of the argument in the answers list.

Edit: I do note that PS use the term 'normally' a lot in discussing this approach. Is this an arbitrary disclaimer, or are the many instances where the 'norm' does not occur, leaving this approach less valuable?

youknowryan
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Re: PS's Justify the Conclusion - 'Mechanistic Approach'

Postby youknowryan » Mon Nov 22, 2010 8:12 pm

Most of the time it will get you down to 1 or 2 possibilities. For the less common, really tough questions, it will knock off 1 or 2 and leave you to read/consider the remaining answer's relevance.

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logicalprep
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Re: PS's Justify the Conclusion - 'Mechanistic Approach'

Postby logicalprep » Mon Nov 22, 2010 8:56 pm

mechanistic approaches are seldomly useful in ALL situations (especially on the LSAT). Their approach is good if you don't have any clue as to what you're doing in sufficient assumption/justify the conclusion questions but not great for really getting the idea of what a sufficient assumption question really wants from you.

What sufficient assumptions really want from you, what LSAC wants from you, is actually a pretty simple and neat idea. They want you to make a logically perfect argument. They want to test you to see if you can figure out what logical perfection looks like.

Take this example (where the author clearly has never heard of a chicken):

All birds have feathers. So all birds fly!

In order to make this a logically perfect argument, we need to add a premise. There will be one such answer choice that we can feasibly 'insert' into the argument above and see if adding that answer choice forces the argument to work, to see if the answer choice forces logical perfection.

Say, for example, we are presented with (A) All flying things have feathers.

We can just 'add' this premise into the argument, making it look like this:

All birds have feathers.
All flying things have feathers.

Now we can ask ourselves the following question: What has to be true here? Really, I can't see much that would have to be true here.. I suppose chickens still have feathers and they definitely don't fly. But even so these premises don't mean that chickens have to fly. Chickens could very well, not be flying at all!

So moving to a hypothetical answer choice (B) All feathered stuff flies.

Now 'adding' this answer choice to the argument gives us this:

All birds have feathers.
All feathered stuff flies.

Now we ask ourselves the same question: What has to be true here?

Well... it seems like all birds would have to fly, since all birds have feathers and feathered stuff flies. We have found our correct, and very forceful, sufficient assumption. Considerably easier to understand when you understand what you should be looking for in the first place. Hope this is helpful.

bee's vision
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Re: PS's Justify the Conclusion - 'Mechanistic Approach'

Postby bee's vision » Mon Nov 22, 2010 11:56 pm

Anytime there's a rogue element in the conclusion of a JTC conclusion, this element must appear in the credited response. I find the mechanistic extremely helpful and timesaving. One of the last questions in the October LR section was a JTC question that I got in seconds and barely read the stimulus. It isn't always so easy, however. The formula still applies but I think LSAC is making it harder to use by making the conclusion harder to find, adding extraneous info in the stimulus, and including this "rogue" element in more answer choices. IMO, yes, it works in most JTC questions but you need to have a very thorough grasp of how and why it works and be able to recognize the situations when it won't.

wanderlust
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Re: PS's Justify the Conclusion - 'Mechanistic Approach'

Postby wanderlust » Tue Nov 23, 2010 12:28 am

i think the trick of the mechanistic approach is that you have to break down the argument into formulas first and foremost, while this skill is not unique to jtc type of stimulus, without it you won't be able to use the approach effectively in problem solving

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JazzOne
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Re: PS's Justify the Conclusion - 'Mechanistic Approach'

Postby JazzOne » Tue Nov 23, 2010 3:50 am

I use a very similar strategy. First, I'm aware that many assumption questions involve the so-called "rogue" idea. I also know that the correct answer must tie the rogue idea back to the argument somehow, so the correct answer choice must specifically refer to the rogue idea. Answers that don't mention the rogue idea are obviously incorrect. However, I am often able to identify a separate idea in the premise that logically relates to the rogue idea. So, I identify not only the rogue idea but also the anchor in the premise that the rogue idea has to be tied back to in order to describe the flaw or fix the argument. It's not just about finding the rogue idea. It's also about finding the anchor.

Furthermore, sometimes the shift occurs in the premises. In other words, there is no rogue idea in the conclusion. Rather the rogue idea is introduced at some earlier point in the logic (i.e., from one premise to the next). These are incredibly easy for me to identify now because they are really just extensions of the "rogue conclusion" type of flaw.

I really like the Bibles, but Princeton Review has a better way of describing these. The term used by PR is "language shift," and I think that is completely appropriate because the argument often uses a subtle shift from one word to another without explicitly stating that the two are related. In those cases, the assumption is that the two ideas are similar enough that the comparison or conclusion is warranted.

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logicalprep
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Re: PS's Justify the Conclusion - 'Mechanistic Approach'

Postby logicalprep » Tue Nov 23, 2010 4:19 am

wanderlust wrote:i think the trick of the mechanistic approach is that you have to break down the argument into formulas first and foremost, while this skill is not unique to jtc type of stimulus, without it you won't be able to use the approach effectively in problem solving


I think this is a very insightful statement.

youknowryan
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Re: PS's Justify the Conclusion - 'Mechanistic Approach'

Postby youknowryan » Tue Nov 23, 2010 3:26 pm

JazzOne wrote:I really like the Bibles, but Princeton Review has a better way of describing these. The term used by PR is "language shift," and I think that is completely appropriate because the argument often uses a subtle shift from one word to another without explicitly stating that the two are related. In those cases, the assumption is that the two ideas are similar enough that the comparison or conclusion is warranted.


Please explain this more in detail:if you can refer to a SA question that would be even better.

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JazzOne
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Re: PS's Justify the Conclusion - 'Mechanistic Approach'

Postby JazzOne » Tue Nov 23, 2010 3:36 pm

youknowryan wrote:
JazzOne wrote:I really like the Bibles, but Princeton Review has a better way of describing these. The term used by PR is "language shift," and I think that is completely appropriate because the argument often uses a subtle shift from one word to another without explicitly stating that the two are related. In those cases, the assumption is that the two ideas are similar enough that the comparison or conclusion is warranted.


Please explain this more in detail:if you can refer to a SA question that would be even better.

I'm gearing up for LS exams, so I don't really have time to dig up my LSAT materials. However, if you PM me an SA question or two, I'll see if I can post a general explanation based on those examples. If you can PM me a couple SA questions, remember to include the PT#S#Q# so I can reference them without being too specific about the details of the question.

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MrAdams
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Re: PS's Justify the Conclusion - 'Mechanistic Approach'

Postby MrAdams » Wed Nov 24, 2010 5:42 am

Thanks for the reply guys. I think a big part of this approach is indeed in being able to find the conclusion; which the LSAT phsychs are doing their best to cover up. Some questions are very straight forward conditional reasoning with simple enough language in the stimulus to apply the method very fast though. I guess I will have to learn when to use the approach and when not to. 16 days, easier said than done.




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