Q19 - In 1996, all ResearchTech

[lhermary]

I'm wondering why E is wrong?

Thanks

[csunnerberg13]

Stimulus structure:
All X are Y or Z.
X1 --> -Y.
Therefore, X1 --> Z.

(A) does not give us a binary situation where All X are one thing or another. Instead, we learn "All X are a variety of things." Eliminate

(B) gives us:
All LR are either P or CL
LR1 --> -P
Therefore, LR1 --> CL
Looks good.

(C) is really close...it gives us:
All LR are either P or PE
O --> -P
Therefore, O --> PE.
BUT, (C) doesn't tell us if O is an LR...if it's not, then our conclusion doesn't hold. Eliminate C.

(D) gives us:
All LR are P or CL.
All 93 are P.
O --> 93.
Therefore O --> LR
This is flawed reasons - that's an invalid inference. We can eliminate because our stimulus does not have a flaw so our answer choice won't have a flaw either. Eliminate

(E) was another close one...gives us:
All O are CL or PSH.
O1 --> -CL
Therefore, O1 --> intended SH
There is a language shift in E that makes it incorrect. We can't conclude anything, in E, about what the mayor intended. All we know is what O's should be for. Eliminate E.

[christine.defenbaugh]

Amazing breakdown csunnerberg13! High five! I love seeing students responding to students - it's the absolute best way to really deepen your own understanding of the logic! Excellent eye on the language shift in (E). Great work!

There are just a few minor things I want to clean up a tad in the whittling down for future readers.

Stimulus:
If 96 --> G or PC
GS was 96
GS was -G
THEREFORE: GS was PC

The Match (B)
If LR --> P or PCL
304 is LR
304 is -P
THEREFORE: 304 is PCL.


The Clashes
(A) some LR are P <======== some is not 'if'!
some LR are PCL
304 is LR
304 is -PCL
THEREFORE: 304 is P

(C) LR --> P or PE
304 is -P
THEREFORE: 304 is -PE <========== concludes the negative!

(D) LR --> P or PCL
93 --> P <=========== introduces new conditional
304 was 93
THEREFORE: 304 was LR <========= reverses a conditional to conclude this

(E) 304 ex --> (should be) PCL or PCSH
last 304 ex was not PCL
THEREFORE: last 304 ex (intended to be) PCSH

The three elements of (E) switch from 1) should be to 2) does not (fact) to 3) intended to be. None of these match!


Note that all of the incorrect answers are logically flawed, in addition to not being parallel.

Nice work csunnerberg13! And lhermary, please let me know if these explanations completely answer your question!