Critical Reasoning

This is a critical reasoning question from Kaplan.


All German Philosophers, except for Marx, are idealists.

From which of the following can the statement above be most properly inferred?

A. Except for Marx, if someone is an idealist philosopher, then he or she is German.
B. Marx is the only non-German philosopher who is an idealist.
C. If a German is an idealist, then he or she is a philosopher, as long as he or she is not Marx.
D. Marx is not an idealist German philosopher
E. Aside from the philosopher Marx, if someone is a German philosopher, then he or she is an idealist.

Ans : E, but why not D

There is a great explanation in the answer section. Start there...

sorry i did not understand your reply....
start from here as in??

gmatrant:

It's not D, because D is just the premise worded differently.

I initially was thinking the same when I did the problem, but in CR's if the premise is part of the solution, it's usually worded differently and is always the wrong answer.

Correct answer is E.

this one was reeeally good gmatrant! ya it should be E...
we need to find the premise for the given conclusion here...you wont believe it but i used a venn diagram for this question and it works!!!

gmatrant wrote:sorry i did not understand your reply....
start from here as in??

Sorry assumed you got the question directly from the Kaplan GMAT Book (this question is part of the 50 practice questions after the CR review). I can type up the Kaplan reasoning if you don't have the book tonight when I get home.

From the Kaplan book:

"Read carefully! You're asked to pick the choice from which the statment can be derived, and that's (E): If, as (E) says, anyone who is a German philosopher is an idealist except for the philosopher Marx, then all German philosophers except for Marx are idealist. That being the case, it would certaily be true that, as the stimulus says, with the exception of Marx, all German philosophers - the folks being a subset of all Germans - are idealists. Now while (E)'s claim that all German philosophers are idealists may sound a bit absurd to you (perhaps you know some German philosophers who aren't idealists), we're concerned with strict logic here, not content.

(A) tells us that except for Marx, if someone's an idealist philosopher, then he or she is German, which is precisely the opposite of what we need: Knowing that all idealist philosophers (except Marx) are German doesn't prove that all German philosophers are idealists, because there could be other kinds of German philosophers. Since the stimulus statement tells us that Marx is a German philosopher who's not an idealist, (B), which contradicts this, is wrong. (C) lets us conclude that German idealists who aren't Marx are philosophers, but we need to conclude that German philosophers (except Marx) are idealists. As for (D), like the stimulus statement, it tells us that Marx isn't an idealist German philosopher, but we need a statement that ensures that every other German philosopher besides Marx is an idealist."

Whew!! Hope that helps.

@ wonder.

Venn diagram for CR, brilliant!
it solves the problem with minimum reasons required to be given.
a highly effective alternate way!

I just want to caution everyone about using Venn diagrams for CR questions. Venn diagrams are great for overlapping sets Quant questions, but they can be misleading as far as CR questions go.

The main reason is that the word SOME could mean 1 or it could mean ALL. So, the Venn diagram for "Some A's are B's" could have a very small overlapping area, or it could be two entirely overlapping circles!

If you draw "Some A's are B's" to just have a small overlapping area, and then you are asked if some A's are not B's, you may incorrectly answer "Yes!"

Again, because the two sets may be entirely overlapping, we cannot say with certainty that there exist A's that are not B's.

I hope that helps. We recommend using line diagrams for CR problems (ie some A -> B) as they avoid this pitfall.

Tatiana

VP_Tatiana wrote:I just want to caution everyone about using Venn diagrams for CR questions. Venn diagrams are great for overlapping sets Quant questions, but they can be misleading as far as CR questions go.

The main reason is that the word SOME could mean 1 or it could mean ALL. So, the Venn diagram for "Some A's are B's" could have a very small overlapping area, or it could be two entirely overlapping circles!

If you draw "Some A's are B's" to just have a small overlapping area, and then you are asked if some A's are not B's, you may incorrectly answer "Yes!"

Again, because the two sets may be entirely overlapping, we cannot say with certainty that there exist A's that are not B's.

I hope that helps. We recommend using line diagrams for CR problems (ie some A -> B) as they avoid this pitfall.

Tatiana

I'm with ya on the line diagrams.. Venn diagrams - never thought of using those for CR questions .. but like u said there could be overlapping issues with 'some .. not all .. ' questions. I just use a crude line diagrams .. didn't know that it was a noted technique Thanks.

- pradeep

this was really an amazing one! clever trap!!