Although the charter of Westside School states that the student body must include some students with special educatio...

Sangwook on January 6, 2015

Help

Please write out logical structure to get to the answer(D). I don't clearly understand the logical difference between (A) and (D) to fill a logical gab between the premise and the conclusion on the stimulus. Thanks,

2 Replies

Melody on January 6, 2015

Here we have a strengthen with necessary premise question. Remember that a premise is necessary for a conclusion if the falsity of the premise guarantees or brings about the falsity of the conclusion. First we check to see if the answer choice strengthens the passage, and then, if it does strengthen, we negate the answer choice to see if its negation makes the argument fall apart. If the answer choice does both those things then it is our correct answer.

Conclusion: the school is currently in violation of its charter.

Why? The charter of Westside School states that the student body must include some students with special educational needs, but no students with learning disabilities have yet enrolled in the school.

Answer choice (A) states: "All students with learning disabilities have special educational needs."

Does this strengthen? No.

(A): LD ==> SEN
not SEN ==> not LD

As you can see, answer choice (A) does not explain what happens when we have no students with learning disabilities. We only know that if there are no students with special educational needs, then we do not have students with learning disabilities. However, the charter states that the student body must have some students with special educational needs.

We still have no information explaining why not having students with learning disabilities means that there are no students enrolled with special educational needs. Remember, those two things are not the same.

Answer choice (D) states: "The only students with special educational needs are students with learning disabilities."

Does this strengthen? Yes.

(D) SEN ==> LD
not LD ==> not SEN

Here was have a logical connection between having no students with learning disabilities to concluding that there will be no students with special educational needs. Answer choice (D) helps explain why since there are no students with learning disabilities, we can conclude that the school is currently in violation of its charter, since not having students with learning disabilities means that there are not any students with special educational needs.

Negation of (D): Students with learning disabilities are not the only students with special educational needs.

Does this make the argument fall apart? Yes.

If students with learning disabilities are not the only type of students with special educational needs, then the fact that "no students with learning disabilities have yet enrolled in the school," is not enough to conclude that there are no students with special educational needs, which would violate the school's charter.

Hope that clears things up! Please let us know if you have any other questions.

Sangwook on January 8, 2015

Thanks a lot!!!^^