LSAT and Law School Admissions Forum

Get expert LSAT preparation and law school admissions advice from PowerScore Test Preparation.

 Administrator
PowerScore Staff
  • PowerScore Staff
  • Posts: 8950
  • Joined: Feb 02, 2011
|
#60884
Complete Question Explanation

Must Be True—Formal Logic. The correct answer choice is (E)

Formal logic questions can be very intimidating for some test takers. However, by diagramming carefully and drawing appropriate inferences, most formal logic mistakes can be easily avoided. Consider each statement individually and then jointly to determine any additive inferences.

First statement:
  • SC = small country
    SH = southern hemisphere
    PS = permanent seat on the United Nations Security council

    ..... ..... ..... SC
    ..... ..... ..... or :arrow: PS
    ..... ..... ..... SH
The contrapositive of this statement is:

  • ..... ..... ..... ..... ..... SC
    ..... ..... ..... PS :arrow: ..... +
    ..... ..... ..... ..... ..... SH
Second statement:
  • IP = increased international peacekeeping
    MR = greater role in moderating regional disputes

    ..... ..... ..... ..... ..... IP
    ..... ..... ..... PS :arrow: ..... +
    ..... ..... ..... ..... ..... MR
Third statement:
  • ISR = increased spending on refugees

    ..... ..... ..... IP :some: ISR
The next step is to find common terms in multiple statements and combine the statements to draw additional inferences. IP is common to both the second and third statements, but the “some” condition of the third statement prevents us from linking it to the second statement. The third statement cannot be used to conclude anything about the permanent members of the UN Security Council
(PS :arrow: IP :some: ISR does not yield any inferences). This is an important inference and will be tested in answer choice (C).

PS is common to the second statement and the contrapositive of the first statement. Combining these two statements produces:

..... ..... ..... SC ..... ..... ..... IP
..... ..... ..... + ..... :some: ..... +
..... ..... ..... SH ..... ..... ..... MR

This inference can be stated in a number of ways, including, “Some countries that are in favor of a greater role for the United Nations in moderating regional disputes are not located in the southern hemisphere.” Thus, answer choice (E) is correct.

Answer choice (A): All that is known about small countries is that they do not have permanent seats on the United Nations Security Council. This information about small countries cannot be linked to any conclusion about their position on refugee spending.

Answer choice (B): Again, one can only know that no country in the southern hemisphere is permanently on the Security Council. It cannot be known whether any of these countries are in favor of or against increased international peacekeeping efforts. This answer choice could be confusing if it were read as, “Some countries in favor of increased international peacekeeping efforts are not in the southern hemisphere,” as that is proven true by the stimulus, but that is not what this answer choice states.

Answer choice (C): It has already been shown that any attempt to draw a conclusion about countries with a permanent seat on the UN Security Council based on the facts of the third statement is invalid. All five countries with permanent seats on Security Council are in favor of increased international peacekeeping efforts and may also be in favor of increased spending on refugees.

Answer choice (D): This answer choice is incorrect for the same reasons that answer choices (A) and (B) are incorrect. The information provided about small countries does not support any inferences about their positions on any of the other topics mentioned in the stimulus.

Answer choice (E): This is the correct answer choice. From the stimulus, one can correctly infer that there are at least five countries (i.e. all the members of the Security Council with permanent seats) that are both in favor of a greater role for the United Nations in moderating regional disputes and are not located in the southern hemisphere.
 8scn
  • Posts: 18
  • Joined: Nov 21, 2011
|
#3103
Hi, why is E a better answer than C? My condition diagramming is:

PS (permanent seats) --> more IP (international peacekeeping) some --> A more S (against more spending)
+ bigger RU (role for UN)

(2 necessary conditions)

So, isn’t C an inference?: PS some --> A more S
Last edited by 8scn on Mon Nov 28, 2011 2:19 am, edited 1 time in total.
 Adam Tyson
PowerScore Staff
  • PowerScore Staff
  • Posts: 5392
  • Joined: Apr 14, 2011
|
#3128
Maybe I am looking at the wrong test - I see the June 2004 LR1 Q15 as being about governments preventing cigarette advertising. Maybe you are looking at an experimental section in your version of that test?
 8scn
  • Posts: 18
  • Joined: Nov 21, 2011
|
#3136
Hi Adam, I'm sorry about the mistake -- I meant to put down Q17 (June 2004, Logical Reasoning 1).
 melissa27
  • Posts: 38
  • Joined: Jan 17, 2012
|
#4298
Can you please explain why answer choice C is incorrect. I narrowed down the answer choices to C and E and picked the correct answer E because I knew I could prove that more, but I don't see how C can be incorrect since it states that "each of the five.." and then states that "some" (which I believe is part of the each of the five, isn't it?)
 Adam Tyson
PowerScore Staff
  • PowerScore Staff
  • Posts: 5392
  • Joined: Apr 14, 2011
|
#4312
Melissa,

In this one I think you've made an unwarranted assumption, that the countries described in the last sentence are a subset of the five discussed in the previous sentence. Take another look at the language in the stimulus - is there any evidence to support that? They didn't say "some of THESE countries" in the last sentence, nor did they say that ONLY the five countries favor increased peacekeeping, etc.

Careful reading of that last sentence should tell you that we are not necessarily still talking about the subset of five countries, but could be talking about any countries, including but not limited to those five.

Adam M. Tyson
PowerScore LSAT Instructor
 ssangha
  • Posts: 6
  • Joined: May 24, 2013
|
#9793
I am having a little trouble diagramming this and getting to E.

My diagram:
Small country ----> No Permanent Seat
Southern Hemisphere -----> No Permanent Seat

Permanent Seat----> In favor of increased international peace keeping efforts

In favor of increased international peace keeping efforts <----S----> Against Spending on refugees

Please Help!
User avatar
 Dave Killoran
PowerScore Staff
  • PowerScore Staff
  • Posts: 5972
  • Joined: Mar 25, 2011
|
#9794
Hi S,

Thanks for the question. You've got the basics of the relationships correct, but I'd try to tie them all together, and that may make (E) clearer for you:

Small country :dblline:
..... ..... ..... ..... Permanent Seat :arrow: Increase/Gr role :some: Against spending
Southern Hemisphere :dblline:

The last three terms do not produce an inference, so you know the inference in this Must question has to come from a connection between the first three terms. the inference that is possible here "goes backwards" over the arrow, and becomes:

..... ..... ..... ..... NOT Small country
Increase/Gr role :some:
..... ..... ..... ..... NOT Southern Hemisphere

Answer choice (E) makes the link the Southern Hemisphere, and is correct.

Please let me know if that helps--you were close! Thanks!
 ssangha
  • Posts: 6
  • Joined: May 24, 2013
|
#9795
Got it! Thank You!!
 amna.ali467
  • Posts: 17
  • Joined: Aug 10, 2014
|
#16443
Hi,

I've looked at the previous posts for explanations to this question, but I'm still confused. Would this question be considered formal logic /conditional reasoning? How would I properly set up this conditional reasoning?


Thanks for the help!

Get the most out of your LSAT Prep Plus subscription.

Analyze and track your performance with our Testing and Analytics Package.