Self-study
Principal: Support All of our school's rural students participate in the school's lunch program because they live too far away to go home for lunch, while Support roughly one half of their urban counterparts also take part in the program. ████ ████████████ ██ ████ ████████ █████████ ████ ██ ███ ████████ █████████ ████████ ██████████ ████ ███████████ ██ ███████████████ ██████████ ████ ██ ██████ ███ ██████ ██████████ ██ ████ ████ ████ ██ ███ ████████████ ██ ███████████████ ██████████ ███ █████ ████████ ███ ████ ███ █████ █████████
TL;DR
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Distilled Summary & Flaw
Here’s a crisp way to think about the argument and its flaw, generated with the help of hindsight:
The pool of Program kids includes both kinds of students (Rural and Urban). Some of the Program kids do Extracurriculars. So the Extracurriculars pool must also include both kinds of students.
Flaw: It doesn’t have to include some of each. Maybe the subset of Program kids who do Extracurriculars are all Urban kids. (ooOo! Maybe all the Rural kids have to drive home early because they live so far away!)
Hella Long; Will Read
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Distilling The Argument
If you manage to boil the stimulus down to the above summary, criticizing it isn’t so hard. The hard part is turning this stimulus into a workable model in the first place. Here’s a realistic walkthrough of how you’d do that in a timed setting:
The stimulus’ first sentence includes two claims about intersecting sets (an
And you should (aspire to) know that both these questions are likely to be answered by looking at the conclusion. Is the conclusion a claim about intersecting sets? (Like “some flips are flops.”) Is it a causal claim? (Like “this phenomenon occurs because of the blops.”)
For now, just file those questions away and keep reading – it’s very likely you’ll have to make another run through this stimulus once you’ve figured out where it’s going.
Sentence 2 is a “some” claim (in fact it’s two some claims), increasing the likelihood that this is one of those questions with all the diagrams and whatnot. Okay keep reading you’ll diagram later.
The last sentence (which, by the way, is the
So let’s run back through and build our structure, starting with the conclusion.
(Note: These individual claims are actually simple enough that you can probably think about them in English on test day. We’re presenting them in formal logic here for your convenience, but if you want English versions, just look up in the stimulus.)
Conclusion pt. 1: Extracurricular ←some→ Rural
Conclusion pt. 2: Extracurricular ←some→ Urban
Starting with the conclusion is nice because it defines the argument’s scope – knowing our precise goal helps us cut out a bunch of irrelevant stuff unrelated to that goal. Let’s jump back to the first sentence, which includes two separate claims:
Premise 1 : Rural → Program
Premise 2 : Urban —most(ish)→ Program
Notice how we left the
Premise 3: Program ←some→ Extracurricular
Notice how we left the
Now we’re a lot closer to the distilled summary at the top of this explanation:
All the Rural kids and most(ish) of Urban kids are in the Program. Some of the Program kids are Extracurricular kids. So the Extracurricular group must include some Rural kids and some Urban kids.
Hella Long; Will Read
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Anticipating The Flaw
Through the formal logic lens, we’re in a classic “chaining conditionals” situation: the conclusions say two concepts are linked (Rural/Urban and Extracurricular), and the premises try to establish a logical chain that leads from one to the other. This argument’s chains are:
Rural → Program ←some→ Extracurricular
Urban —most(ish)→ Program ←some→ Extracurricular
In Flaw questions involving lots of formal logic, you don’t need to get too technical in describing what went wrong unless the argument commits the specific “necessary vs. sufficient confusion” flaw (which this argument does not).
For our purposes, the important thing is to recognize that the “some” link between Program and Extracurricular is too weak to support a connection between Rural/Urban and Extracurricular.
So it’s enough to anticipate that our flaw will likely highlight the weak link between Program and Extracurricular. It’ll be something like “just because the Program group has both types of kids doesn’t mean any given subset of that group must have both types of kids.”
(Extra Credit: If you’re up to date on your valid argument forms and you have a big ol’ brain, you could say our Rural chain would work if the “some” claim came before the “all” claim, and our Urban chain would work(ish) if you added this: Urban –most(ish)→ Extracurricular. That would be a real flex.)
23.
The reasoning in the principal's ████████ ██ ██████ ███████ ████ ████████
a
takes for granted ████ █ ███████ ██████ ██ ██████ ████████ █████████ ████ █████ ███ ███ ███ ██████ ████████ █████████ ███████████ ██ ███████████████ ██████████
You can evaluate these “takes for granted” claims as necessary assumptions – we’re accusing the argument of needing this claim to be true or else it falls apart.
And it is certainly not necessary for our argument to compare two different categories of academic achievers (strong vs. not strong) to one another, especially because the stimulus itself doesn’t make that distinction, instead just talking about “the strongest.”
b
takes for granted ████ █ ███████ ██████ ██ █████ ████████ ████ █████ ████████ ███████████ ██ ███████████████ ██████████
You can evaluate these “takes for granted” claims as necessary assumptions – we’re accusing the argument of needing this claim to be true or else it falls apart.
(B) certainly points out a potential flawed inference you could make based on the premises. If all the Rural kids are in the program but only half of the Urban kids are, a non-logician might think that means more Rural kids do Extracurriculars.
But our argument doesn’t make that particular mistake. The conclusion only requires one Rural kid and one Urban kid to be doing Extracurriculars, so the argument can get by just fine without this specific claim about how the proportions of the two groups compare.
c
ignores the possibility ████ █████ ███ ███████████ ████ ██ ███ █████ ███████ ███ ██ ███████████████ ██████████ ██ ███ ███████ ████ █████ ███ █████ ████████
The argument’s basis for “knowing” that both kinds of students do Extracurriculars is the idea that both kinds of students are in the Program, and some of the Program kids do Extracurriculars.
But (C) is right – just because the Program group and the Extracurriculars group overlap doesn’t mean the Extracurriculars group draws a healthy, varied sample from the Program group. Maybe the subset of Program kids who do Extracurriculars includes zero Rural students (perhaps because they all have to start driving home early).
d
ignores the possibility ████ ████ █████ ███ █████ ████████ ████ ████ █████ ████ ██ █████████ █████ ████ ███████ ███████████████ ██████████
Our argument does this, but doing it doesn’t matter.
There is indeed a possibility that Extracurricular activities are just a few of the many ways kids can spend their time. I’d even call it a fact. And the argument does indeed ignore this possibility…
…because it’s not at all relevant to the argument’s conclusion, which is about what kinds of kids do Extracurriculars.
(D) wants an argument like “These kids have to spend their time somehow. Therefore they must be doing Extracurricular activities.”
e
at first uses ███ ████ █████████████ ██ ███ █████ ███ ████ █████████ ██████ ███ ██████ ███████ ██ ██████
Equivocation is a common flaw, and it means exactly what (E) says – subtly changing the meaning of a key term over the course of an argument.
Equivocation often reads like a pun. Like maybe a billboard says “Looking for a sign? This is it!” Get it? Because sign can mean omen but also the billboard is a literal sign! Get it?
But as with thousands of other wrong answers on the LSAT that point cleanly to a different common flaw than the flaw displayed in the stimulus, this argument simply doesn’t equivocate: participate just means “attend” throughout.
Equivocating on “participate” would be premises that use participate the way this argument does (i.e. attend), and a conclusion about whether these kids participate in class (i.e. raise their hands and actively contribute).