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 GGIBA003@FIU.EDU
  • Posts: 25
  • Joined: Sep 14, 2020
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#80807
Hi,
I've read the full Formal Logic PDF and am working on the drills and reviewing with Answer Key. On #8 of the Drill: Diagramming and Making Inferences, I incorrectly wrote the diagram.

I used abbreviations of: SH (students in Henry's class), A (grade A), B (Benson award)

My diagram: SH :most: A :some: B
Because of the "at least 1 A" I interpreted the 2nd statement as: A :some: B. The PDF indicates that "at least 1" indicates Some. So I'm confused as to why the diagram is written as: Every A is B (A :arrow: B).

Because I wrote the diagram incorrectly I wrote out an incorrect inference of: SH :some: B. Which I now realize is incorrect because we can't infer from a "Most" to "Some" diagram, correct?

Can someone please point where I made the mistake. :hmm:

Thanks in advance!
 Paul Marsh
PowerScore Staff
  • PowerScore Staff
  • Posts: 290
  • Joined: Oct 15, 2019
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#80857
Hi GGiba!

You are right that "at least one" and "some" mean the same thing on the LSAT. But "At least one" is not what's modifying "students" - "Any" is what's modifying "students" here. Remember that "any" is one of our sufficient indicators, so that's why we can write this as: If student who gets at least one A :arrow: eligible for Benson's.

For what you wrote, A :some: B, we would need our sentence to instead say: "At least one student who gets an A is eligible for the Benson award". In that case, "at least one" would be modifying the "students".
Because I wrote the diagram incorrectly I wrote out an incorrect inference of: SH :some: B. Which I now realize is incorrect because we can't infer from a "Most" to "Some" diagram, correct?
That's exactly right. We could not make that inference, even if your diagram were correct. (In other words, if this problem really did say SH :most: A :some: B). This is because there could be other students not in Mr. Henry's class who get A's, and it's possible that those non-Henry students are the only ones eligible for the award.

The main takeaway here is to be careful when we appear to have multiple quantitative words getting tossed around. In this problem we had "any" and "at least one" in close proximity, but only one of those was actually describing the students.

Hope that helps!

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