PTB.S4.Q11 - On the basis of research with young children...

md753

Why is B the right answer for a strengthen if the reverse could also be true: what if those who can copy angles can copy curves just means the other comes first. Isn't the key to the argument the idea that one is before? #help

Clemens_

The author wants to argue: The skills to copy curves must be developed before the skills to copy angles. In other words, the author claims that the ability to copy curves is necessary for the ability to copy angles. Formally, the author thus seeks to establish: If COPY ANGLES, then COPY CURVES.

We are asked to strengthen this hypothesis. That is, we are supposed to identify an answer choice whose truth would make it more likely that the author's claim is correct.

(A) This answer choice talks about the ability to copy lines, it does not get at the conditional statement we are trying to strengthen.
(B) Here we get: If you can COPY ANGLES, then you can COPY CURVES. This is exactly the conditional relationship that the author tries to establish, just in a different natural language formulation. If this conditional is correct, then the author's position indeed becomes much more supported.
(C) This answer choice talks about the ability to discriminate angles, and thus does not relate to the conditional statement that we are considering.
(D) COPY ANGLES <-s-> not COPY CURVES. This is the logical contradiction of what the author is trying to claim and thus very much does not support the author's position.
(E) This answer choice considers only one of the two abilities the relation between which we are trying to ascertain.

Long story short, what matters is the logical structure of the conditional statement that the author is trying to establish. The crucial point to recognize here is that the author wants to establish that something is a necessary condition for something else ("must be"). If this sort of question is giving you trouble, consider retaking those parts of the core curriculum that talk about the formalization of natural language statements into their logical form. Put yourself in the position of being readily able to transcribe "if then" statements and their variations, practice the recognition and distinction of necessary and sufficient conditions.