#21 - Not all tenured faculty are full professors. Therefore

[Yaa]

Hello. The only problem I have with this question is mechanically diagraming answer A. I understand that this answer logically make sense? However, when I mechanically try to set it up, the all arrow faces the some relationship, which goes against the some train method, which would not be logically correct? --- I'm confused... I chose C as the correct answer because it parallels with the stimulus. But, I still want to understand answer A.

[Dave Killoran]

Hey Yaa,

You ask a good question. Let's walk through the diagram for A, step-by-step (I'll use a
"not" instead of a slash on the variables due to the graphical limitations of the forum tools):

The first part of the first sentence is diagrammed as:

MOT = Modern office tower
CC = climate controlled:

MOT --> CC


The second part of the first sentence is diagrammed as:

OB = Office buildings

OB some not CC

So, we have an issue because we want to link these two statements together, and the only common connection is CC, but it is positive in the first part and negative in the second part. We can't do anything with the negative CC in the second part because it is attached to a "some" relationship, but we can turn the CC in the first sentence into a negative by taking the contrapositive:

not CC --> not MOT

This manipulation allows us to connect the two parts into a chain:

OB some not CC --> not MOT

With this chain, we can validly conclude that "some OB are not MOT." Because "some are not" is identical to "not all," we have the same conclusion that is drawn in answer choice (A).

Please let me know if that makes sense. Thanks!

[JennuineInc]

Hi,

Can someone please diagram out the stimulus and all the answers? Thank you

[Emily Haney-Caron]

Hi Jennuine,

We can definitely help with this, but I think the best way to start to get the hang of it is to take a stab at it yourself, even if you're not 100% confident. Take your time with it, post the diagrams you come up with, and we can give you feedback as needed.

[rmbedge03]

Hello,

I am having difficulty seeing what the flaw in the stimulus is and I think my issue may be with diagramming. My diagram for the stimulus is:

Tenured Faculty ---> not full professors

Faculty in linguistics ----> Tenured Faculty

Conclusion: Faculty in linguistics ----> not full professor

Based on my diagram it seems like the conclusion follows, which I know is incorrect. Could someone please help?

Thanks

[Luke Haqq]

Hi rmbedge03!

So, I can suggest a handful of things on the diagrams you offered:

Tenured Faculty ---> not full professors

This says if someone is tenured, then the person isn't a full professor. We don't know that--we just know that not all tenured faculty members are full professors. What that means is we know there's at least one person who is tenured but not a full professor. This could be represented with the diagram:

Tenured Faculty not full professors

Faculty in linguistics ----> Tenured Faculty

Great! That's the correct diagram for the second sentence.

Conclusion: Faculty in linguistics ----> not full professor

As with the first sentence, when you see "not all," think of that as equivalent to "some" or "at least one." So instead of what you have, that last part should be diagramed:

Faculty in linguistics not full professor

If you put those together, they parallel the same faulty reasoning in answer choice (C):

Buildings designed by famous architects are not well proportioned,
All government buildings are designed by famous architects.
Therefore, government buildings not well proportioned.

[rmbedge03]

That clarifies it. Thank you!

[taylorballou]

Hello,

Could you please confirm the diagram for answer choice D? I'm not too familiar with formal reasoning and I wanted to double check.

I got Private Use <-S-> Public Buildings <-S-> Well Designed.

Thank you,

Taylor

[AthenaDalton]

Hi Taylor,

Thanks for reaching out! Your diagram for answer choice (D) works. As you can see, the chain of reasoning that private buildings used as public buildings poorly designed does not give us enough information to support the idea that all poorly designed public buildings were originally intended for public use. Although this reasoning is flawed, it doesn't match the type of flaw in the stimulus which Dave explained and diagrammed above.

Best of luck studying!

[LSAT2018]

Stimulus:
Tenured Faculty → Not Full Professor
Tenured Faculty (Linguistics Department) → Not Full Professor (Linguistics Department)
I thought that there was valid resaoning used in the stimulus so shat is the flaw in the reasoning here? Please look through the answer choices as well.

Answer choice (A): Valid Reasoning (Chain)
Modern Office Tower → Climate Controlled
Office Building → Not Climate Controlled
Office Building → Not Modern Office Tower

Answer choice (B)
Municipal Hospital → Massive
Municipal Hospital → Not Forbidding
Massive → Not Forbidding

Answer choice (C): Valid Reasoning (Chain)
Building by Famous Architect (Some) → Not Well Proportioned
Government Building → Building by Famous Architect
Government Building (Some) → Not Well Proportioned

How is this parallel to that in the stimulus?


Answer choice (E)
Cathedral (Some) → Not Built of Stone
Cathedral → Impressive
Building (Some) → Impressive → Not Built of Stone