LSAT Course Homework p309 Parallel Reasoning #2

[KathrynJ]

Hello,

Please redirect me if this is addressed elsewhere.
In our lesson on parallel reasoning questions, I thought I understood that the positive or negative conditions of the components didn't matter.
However, a contrapositive of a conditional does matter.
So, with question 2 on p.309, I was deliberating between B and E. I almost went with B, because they both had a contrapositive element. But, ignoring the negative or positive dimension, E seemed to be a better fit.

So, is it erroneous to tell us we can disregard the positive and negative, because of contrapositives? (i.e. contrapositives must be respected?)

Thanks!

[Steve Stein]

For parallel reasoning we want to parallel the components of the argument, and in this case, that argument is conditional and uses the contrapositive, as follows:

recession --> low demand --> low interest
therefore: NOT low interest --> NOT recession

The correct answer choice, A, parallels this nicely:

fish ready --> cooked through --> white
therefore: NOT white --> NOT ready

Both arguments use the contrapositive to draw a proper inference.

Answer choice E comes close:
Forecasts right --> inflation --> governing party lose
therefore: governing party lose -->

As we can see, the contrapositive is not drawn correctly in that case.

Let me know whether this clears that one up--thanks!

~Steve

[KathrynJ]

Thanks. Let's see if I'll be able to get that right.