Q21 - If the parking policy is

[chike_eze]

I arrived at the right answer by process of elimination, but I had to review the question one more time to understand why E is the correct answer. My issue was with this phrase "And, it is bound to be unpopular either with faculty or among students", which I interpreted as unpopular with faculty or students or unpopular with both. Is "both" warranted in this situation? Diagram below...

-PF --> M
-PS --> N

-PF or -PS (inclusive)
which evaluates to PF --> -PS OR -PF and -PS

(E) translates to PF --> N
Must be true because we know -PF or -PS,
so PF --> -PS ( -PS must be true).
and we know, -PS --> N
which means, PF --> -PS --> N,
therefore, PF --> N

Except for -PF and -PS inference, the steps above are similar to explanation in the strategy guide. Please confirm or deny the -PF and -PS inference.

[ManhattanPrepLSAT1]

-PF or -PS (inclusive)

Is "both" warranted in this situation?

You are absolutely correct that "or" statements are inclusive, unless you see the phrase "or else" or if you see the presentation between two alternatives which by definition are mutually exclusive. An example that comes to mind is a question that says, "in this word you are either rich or you are poor."

Given that claim it would not be fair to assume that one could both be rich and poor. But in this situation the terms are not mutually exclusive and so it is possible that the policy will be unpopular with both.

-PF --> M
-PS --> N

PF --> -PS OR -PF and -PS

Obviously the first two statements look good. The last one I would set up as you had it PF ---> ~PS and leave it at that.

From the three statements

~PF ---> M
~PS ---> N
PF ---> ~PS

We can get the following two inferences...

Combining the first with the third we could get

PS ---> M

and combining the second with the third we could get

PF ---> N

And the latter is represented in answer choice (E).

Does that answer your question?

[chike_eze]

That answers my question. Thanks.

[patrice.antoine]

So in this inference question, we cannot assume that both faculty and students can find it unpopular? This question threw me off because I thought outside either/or it could mean both.

[ManhattanPrepLSAT1]

It definitely is possible that both could find it unpopular according to the stimulus - but it cannot be inferred that both would find the new policy unpopular.

Great thinking though, because that possibility is not excluded from an "either/or" statement!

[patrice.antoine]

Thanks Matt.

I had quickly eliminated D and E because the stimulus did not directly say anything about "popular" but rather unpopular. I didn't want to assume that because it could be unpopular with one group it directly meant it would be popular with the other group. Then again, I guess the opposite of unpopular, is popular.

Very tricky/confusing.

[ManhattanPrepLSAT1]

I didn't want to assume that because it could be unpopular with one group it directly meant it would be popular with the other group.

That's true... Just because the policy is unpopular with one group, we cannot infer that it would be popular with the other. But the inverse is true. The last sentence allows us to infer that if it is popular with one group that it will unpopular with the other!

Definitely a tricky question!

[Aquamarine]

I have a question.
I understood the diagram.

~PF ---> M
~PS ---> N
PF ---> ~PS

But what if the diagram like this?

~PF ---> M
~PS ---> N
~PF ---> PS

If I diagrammed like this, I couldn't reach answer E at all.
It looks like the last one should be PF---> ~PS, not ~PS---> PF.
But why? I mean the stimulus said "unpopular either with the faculty or among students".

Please someone enlighten me.
Thanks!

[Mab6q]

I think you are getting popular and unpopular mixed up here. We have to have either ~PF or ~PS, which wound be diagrammed as PF --> ~PS. You wrote: ~PF ---> PS, which not what we want because it opens leaves the possibility of have the policy being popular among both.

[abkrusemark]

I am confused about the conditional logic in this question. It appears that the phrase "And, it is bound to be unpopular either with the faculty or among students" is a conditional statement.

When setting this up, do you always put your desired result on the necessary side (PS --> - PF) as opposed to vice versa?

However, I am not seeing how they could both be unpopular, if it is triggered by the other being popular.

[maryadkins]

One of them has to be unpopular.

This doesn't mean that both of them cannot be unpopular.

PF --> ~PS

PS --> ~PF

We only have triggers of one being popular; one being UNPOPULAR isn't a trigger, and you can never read the statement backwards.

I don't know if this answers your question...

[a8l367]

Why not C?
If we shold modify the policy then it's unpopular with the faculty . But what could be the reason to modify it so to make it even more unpopular?