Say It Ain’t So!

A new animal reared its ugly head in the Logic Games section a few years ago – the “rule substitution” question, which asks you which of five possible alternate rules would “have the same effect” on the scenario.  Essentially, if you swapped out one existing rule for the right answer, the same arrangements would be permitted, and the same arrangements would be prohibited.  Here’s a ridiculously simple example:

Six runners, Adam, Brianna, Carlos, Duff, Enya, and Frank, are competing in a race.  They all finish the race, and there are no ties for any of the places.  The order in which the runners finish is consistent with the following statements:

Adam finishes immediately before, or immediately after, Frank.

Carlos finishes after Adam.

 

Which one of the following, if substituted for the statement that Carlos finishes after Adam, would have the same effect on determining the finish of the runners?

A correct answer: Frank does not finish after Carlos.

I’ll dispense with making up a bunch of wrong answers, so we can take a look at why the correct answer is correct.  Often, in sequencing games, you’ll have a rule such as the first one here, which says that two people are consecutive, without saying which one comes first.  The most obvious consequences of this rule are that anyone who finishes before one of the two people must also finish before the other one, and anyone who finishes after either of the two people must finish after the other one.

If that’s a little unclear or abstract, look at it this way.  Let’s say you go to a movie with your mom, and you walk in together, either you right before mom, or mom right before you.  If I walk into the movie after you, I’m also going to walk in after your mom, right?  There’s no room in between you.

So in the original scenario, Adam and Frank are Siamese twins – everyone else either goes before, or after, both of them.  Carlos, therefore (per Rule 2), goes after both of them.  The correct answer is correct because if Frank doesn’t finish after Carlos, then Carlos must finish after Frank (and also, therefore, Adam).  It says the same thing as the original rule – Carlos finishes after the Adam/Frank block.  We don’t have to know what order Adam and Frank are finishing in to know this.

Unfortunately, real rule substitution questions are much more difficult than this.  They’re generally (by far) the most difficult AND the most time consuming Logic Games questions.  They didn’t exist until fairly recently; when they came into existence, they appeared in most exams.  Sometimes, though, there was no rule substitution question.  When there was one, there was always only one, and it was always the last question on the particular game where it cropped up.

In late 2012, for the first time since rule substitution questions debuted, they failed to appear on two consecutive released exams – October and December (Preptests 67 and 68).  It seemed that perhaps the rule substitution question was a thing of the past – an experiment that was being discarded.  Preptest 69 (June, 2013) crushed that dream, as it featured a rule substitution question.  The most recent Preptest gives a strong indication that rule substitution questions are here to stay – In December, 2013 (Preptest 71), for the first time, the Logic Games section had not one but TWO rule substitution questions.  Brutal.

So, what can you do about it?  First and foremost, make sure your practice includes recent Preptests.  If you’re only working on Preptests from the 40s and earlier, you probably haven’t even SEEN a rule substitution question.  The LSAC’s “Ten Actual…” series is a great, cost effective way to purchase multiple Preptests, but the only one that is recent enough to include rule substitution questions is “Ten NEW (emphasis added) Actual, Official LSAT Preptests.”  For more recent individual Preptests, go to Cambridge LSAT.

That’s not to say, by the way, that it’s bad to work off of old Preptests.  They’re ALL useful; the test doesn’t change all that much.  But it does change, and you want to stay on top of those changes, especially when an entirely new question type is introduced.

Second, many people don’t finish the Logic Games section anyway.  They’re working on the third game when they get that five minute warning, and they guess their way through the last few questions.  If that’s you, DON’T even bother with the rule substitution question(s).  They drain too much time, and you might wasted a bunch of time and miss it anyway, because they’re hard.  Let’s say you struggle through a rule substitution question in the first time.  You might run out of time on question 16 and guess on the last seven questions.  But if you’d skipped the rule substitution question, you might run out of time on question 19 and guess on the last four questions (plus the rule substitution question itself).  If you’re not going to finish the section anyway, it’s absolutely not worth the time investment to mess with the rule substitution questions.

Hopefully you’ll get lucky and take one of the tests that doesn’t have a rule substitution question!  But in case you do…be prepared!

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