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#5- Most parents who are generous are good parents, but some

scyq6@sina.com
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Hello,

I find it somewhat confusing with the setup of this problem. Can you please help with the diagram here? How do I determine which is the correct answer?

Thank you!
Dave Killoran
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Hi scyq6,

Thanks for the question! This is a Formal Logic problem, and so you have to be familiar with how "all," "some," and "most" statements work. So, that's the first question I have for you: have you worked with those statements before, and if so, how comfortable are you? If you can tell me how you've been studying thus far (what materials you are using, etc), then I can tell you when you will encounter these concepts in the course of your studies, and what to look for in the meantime.

Next, it's a matter of capturing each relationship. The stimulus is pretty short, and each statement is fairly concise. So, let's look at each one and diagram them:


    1. Generous Parents :most: Good Parents

    2. Self Centered Parents :some: Good Parents

    3. Good Parents :arrow: Good Listeners

Those three statements actually combine quite well (but the forum doesn't really have the proper tools to make this look the way I'd diagram it). The first two statements connect to the third statement through the common term of Good Parents. It would look kind of like this:


    Generous Parents :most: Good Parents
    ..... ..... ..... ..... ..... ..... ..... :arrow: Good Listeners
    Self Centered Parents :some: Good Parents


From there it is a matter of identifying the standard inferences that follow from these statements. The first chain is:


..... Generous Parents :most: Good Parents :arrow: Good Listeners


And that results in the inference that:


..... Generous Parents :most: Good Listeners


The second inference results from the following chain:


..... Self Centered Parents :some: Good Parents :arrow: Good Listeners


And the inference is:


..... Self Centered Parents :some: Good Listeners


This second inference is identical in meaning to answer choice (D), and thus (D) is correct.


Formal Logic isn't tested very frequently on the LSAT, but it often causes problem when students first see it. While this may look rather complicated, after you've seen problems like this a few times and become familiar with how they works, this is actually a problem that you can complete relatively quickly and with 100% confidence that you nailed it. Let me know how you are studying and we'll talk about it more.

Please let me know if that helps. Thanks!
Dave Killoran
PowerScore Test Preparation

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scyq6@sina.com
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Thank you very much! I haven't started the actual course yet. I went through the bible by myself and I read this section quickly, so I didn't comprehend the diagram very well. Your explanation helps a lot!
rowdy
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Quick question,

What element of the stimulus suggests that we should use a double arrow to link Self Centered Parents and Good Parents? I now see how to correctly diagram some and most, but can't determine how we can know to use a double arrow.

Thanks
Adam Tyson
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Hey Rowdy, love the name, just don't cause a disturbance at the testing center!

The double arrow is implied in any "some" statement. If some self-centered parents are also good parents, then it must be true that some good parents are self-centered parents, right? There has to be at least one person in both categories. That's one of the things that distinguishes formal logic from conditional language, the two-way nature of some (there is no such double arrow inference in a standard conditional claim, like "if you are a good parent then you must be a good listener").

Check out whatever resources you have, be it our course books or bible series or the online student center if you have access to that, to find modules and homeworks on formal logic, and this should get cleared up for you.
Adam M. Tyson
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