Q12

[MitchellL341]

Would someone please explain how they got #12 correct with speed and efficiency? I found myself testing most of the ACs. Thank you.

[Laura Damone]

Hi!

Question: In what order did you test the ACs? If you went in order, you'd only need to test two answers to get to the correct choice, which is very efficient for a Rule Substitution question!

There is, however, a way to prephrase the correct answer. First, look at the rule you're trying to sub out: J --> -Y ; Y --> -J. Then, look at the other rules that address J and Y to see if you can come up with a new rule that you could link to those existing rules that would effectively prevent J and Y from being selected together.

Since the first J rule is just about which slot J occupies, it's not likely to be much help. The other Y rule, however, is very likely to help because it gives you another element that Y can't be selected with: P.

So, how do you effectively make J --> -Y when all you know is P --> -Y? You connect J to P such that J --> P --> -Y . Thus you can prephrase B: J is selected only if P is selected.

If you recall the "split the conclusion" technique for Sufficient Assumption questions, this should be familiar!

Now, for a lot of test takers, Rule Sub questions are almost never going to be worth the time they take. If, after thinking about it, this question still makes your brain hurt, here's a little strategic tip. Also much like Sufficient Assumption questions, if you're really confused and just need to blind guess and get out of there, see if any answers are the reversal of one another. If there are two answers that reverse one another, there's a solid chance that the LSAT is testing whether you can pick the right order. So, if you gotta guess, guess one of the two reversed answers. Applying that strategy to this question would give you a 50/50 shot between A and B.

Hope this helps!