Some Train Diagramming Drill #2

[Dave Killoran]

This post is in response to this tweet:

First, as noted in the introduction to the drill at the top of the page, the LRB website has an expanded explanation of every item in this drill. If you have a chance, please check that out.

Second, if you answered #1 in this drill correctly, this one has the exact same structure as that one. The difference? The "not E" in the middle. But, since that "not E" is in the middle, we just skip right over it and it doesn't change anything at all.

Last, here's how to analyze this one:

• Start at D. From there we can ride over to the "not E" via the "some" between the two. Because we then have an arrow from "not E" over to F, we can follow that chain, allowing us to go from D over to F. Thus, we have an inference between the two. What is the inference?
  
  The weakest link in the chain is "some," so we have a "some" inference between D and F. Is there any relevant negativity? No, although "E" is negative, we skipped right over that since it was in the middle of the chain, and since there is no negativity on D or F or in either relationship, we have no relevant negativity. Thus, the inference is D F.

Please let me know if that helps. Thanks!

[whoonfirst]

This was my question exactly. Thanks for asking and answering it.

I was looking online trying to find the explanations to these problems, but couldn't find it. Do I have to create an account on Powerscore? I tried but received "Unfortunately, you are ineligible for registering an account at this time." I'll try again or try calling during normal hours. If I do not need an account, would you post a link to where these are located?

[Stephanie Oswalt]

Hi whoonfirst,

We are glad to hear this response was helpful!

The PowerScore Student Portal that you are attempting to register for is used by our course students, or those who have directly made a purchase on our website before. A PowerScore portal account is typically for students so they can access course material, or track their purchase (similar to an Amazon account).

If you are looking to access additional information regarding one of our LSAT publications, you can go to the second or third page in your book—the book site address for each book is listed there, in the introductory page!

Thanks!

[gwu2019]

Hello PowerScore,

I appreciate the tools and resources you supply through the Bible and Workbook. In reviewing and after looking through the explanation online for this problem, I fully comprehend the "some train" law that we follow to create additive inferences from these statements.

What I am having trouble with though is understanding how. I can memorize and remember the law to create the inferences, but I don't understand how, in Some Train Diagramming Drill #2 that some D's are F's? To me, it seems as if they have no relation in this problem because of the "not E" in the middle of the train being a non-factor in the connection. I have tried understanding these problems by using circles for each letter, showing D as a circle, showing E as another circle, and then showing F as a circle. This doesn't seem to be helping me with this problem but has helped in previous problems, by overlapping circles that are within the bounds of each other. So, I was just wondering if there was any other way of explaining this problem without using the Some Train to help me comprehend it better?

[James Finch]

Hi GWU,

Maybe if we write out the conditional statements it would make more sense. The first conditional is:

D E

or:

Some Ds are not E

Then we have:

E F

or:

If not E, then F

Putting the statements together we get:

Some Ds are not E, and those that are not E are F, so some Ds are F. Or as the diagram has it:

D E F

Let me know if this clears things up!

[gwu2019]

Hi James,

Yes this explanation cleared everything up. The problem for me was trying to put it into words and that's exactly what you did. Thank you so much.