Logical Reasoning problem set #1, question 7

[Nishbha]

Can you help me diagram this problem? I get confused with "no" and "all" when deciding which part of the statement is conditional and which is necessary. Thank you

[David Boyle]

Can you help me diagram this problem? I get confused with "no" and "all" when deciding which part of the statement is conditional and which is necessary. Thank you

Dear Nishbha,

What book or other medium is this in, and what page or pages? Thanks,

David

[Nishbha]

It's from the online supplement and it's labeled "Logical Reasoning Problem set 1". It doesn't have any page numbers however it is problem 7 in the aforementioned problem set. It's a conditional question regarding capulets and montagues.

[Dave Killoran]

Hi Nishbha,

I think this post was pushed down on the list when it received a reply, but I see the the reply doesn't answer the question. So, lt me see if I can help out here

Let's look at the first two sentences to include "no" and "all."

• "No Montague can be crossed in love."
  
  When you have a sentence form like the one above, which is basically the same as "No Ms are CIL," the "no" actually transfers to the second term (B). In this sense, "No Ms" is identical "All Ms are not..." An easy way to think of this is to ask yourself what you know about Montagues? Well, all of them cannot be crossed in love. Then, because "all" is a sufficient condition indicator, that means the representation would be:
  
  M crossed in love
  
  
  "All Capulets can be crossed in love."
  
  Here, use the "all" to see that Capulets are the sufficient condition, leading to a diagram that appears as:
  
  C can crossed in love

The combination of the two statements above correctly yields the conclusion that Capulets are not Montagues (they have opposing necessary conditions, so they cannot be the same).

However, the correct answer relies significantly on the last sentence of the stimulus: "Anyone who is not a Montague is intemperate." This is diagrammed as

M intemperate.

Thus, anyone that is not a Montague is intemperate. Well, Capulets are not Montagues, so automatically from the statements here we know that Capulets are intemperate. And that is what is stated in answer choice (E).

Think about words such as "all" and "no" as road signs: when you see them, they are always telling you something consistent. In those instances, you can typically process the statements very quickly without really thinking about the content (I've posted a lot about this--start here http://forum.powerscore.com/lsat/viewto ... 628#p10628 if you want to read more about that). There's also a lesson concept module that is posted in the Online Student Center where I talk about conditional reasoning and how to think about indicator words like these. That's in the Lesson 2 section.

Please let me know if that helps. Thanks!