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Essential Concepts
Skateboarders use vocabulary unique to them. So do professional kangaroo
wrestlers. Not to be left out, there is vocabulary to express core concepts in LSAT
Logical Reasoning that is fundamental and will lay the foundation for your success.
The purpose of this section is to establish the right frame of mind to tackle
the Logical Reasoning section. To that end, we’ll introduce six important concepts
that will appear in some form on your test:
- Necessary and sufficient conditions
- Cause and effect
- Alternatives
- Bait and switch
- Unknowables
- Loose ends
Essential Concept #1: Necessary and Sufficient Conditions
LSAT test makers are especially enamored with the distinction between
what’s required to bring about a result (a necessary condition)
and what by itself is enough to bring about a result (a
sufficient condition). It’s not hard to figure out the relevance of this
distinction to the study and practice of law. Say, for example, that the Duke of
Gloom Manor was found murdered in the night, the autopsy revealing death by
strangulation. In keeping with mystery folklore, Jeeves, the butler, is the
primary suspect. Now if the police determine that Jeeves possesses
sufficient strength to strangle the Duke, that’s not enough
to implicate him in the crime; just because he could have done
it doesn’t mean he did. But if Jeeves’s power is found to be
necessary for the murder to have occurred (that is, no one else
possessed sufficient strength to strangle the Duke), that’s a different story—it
strongly suggests that Jeeves is in fact the culprit.
Necessary and sufficient conditions are an important subset of formal
logic, which we’ll discuss in greater depth later. The tricky thing is that
these conditions are often hidden in seemingly ordinary language, and it’s up to
you to recognize statements of necessity and sufficiency no matter what form
they take. Consider the following:
Logical Reasoning success is contingent upon your ability to recognize and understand the common logical structures, elements, and nuances that appear in the section test after test, year after year.
“Contingent upon your ability” means that the ability described is
required—that is, necessary for Logical Reasoning success. In
other words, without such ability, one will not achieve Logical
Reasoning success. But does that mean that possessing such ability will
guarantee success? No, and that’s the distinction you’re
expected to understand. Familiarity with common Logical Reasoning elements is
not, by itself, sufficient to guarantee success, even though it
is one necessary requirement. That’s because there may be other requirements as
well, such as the ability to read quickly under time pressure. Take a look at
this statement:
If Martin recognizes and understands the common logical structures, elements, and nuances that consistently appear in the Logical Reasoning section, then he will attain Logical Reasoning success.
This is not inferable from the statement before it—it
represents a classic case of mistaking something that’s
required to bring about a result for something that’s
enough to make it happen. Stay alert to this distinction;
you’re likely to see it in many forms. In fact, you’ve seen it once already—go
back and reread “Uncle Charlie and Aunt Selma” on the first page of this
chapter. If it confused you then, it should make more sense now.
Essential Concept #2: Cause and Effect
Lawyers are naturally very preoccupied with the issue of cause and effect.
When untangling matters ranging from traffic quarrels to billion-dollar
disputes, it pays to understand what causes what, what could
not have caused what, what might have been caused by something else,
and so on. Cause and effect is a particularly common source of misunderstanding
and thus finds itself at the heart of some Logical Reasoning questions. What
claims of causation do you notice in the following scenario? Might there be
other possibilities?
From September through December of this year, Amalie had been very shy and self-conscious around her classmates, causing her to shun social interaction. In March, however, she began displaying noticeable confidence and sociability, which was also the month she began to participate in a very popular after-school drama workshop. Clearly, the workshop has worked wonders for Amalie’s self-esteem.
Ironically, the cause-and-effect relationship that’s suspect here does
not concern the statement with the word
causing in it, as there’s no reason to doubt that the
self-consciousness that Amalie exhibited could lead her to shun social
interaction. There’s greater room for debate regarding the author’s conclusion
that the workshop has increased Amalie’s self-esteem. Why? Because it’s also
reasonable to suppose that a boost in self-esteem may have caused Amalie to
participate in the workshop. Or, perhaps, there’s no relationship between her
confidence and her workshop participation; maybe the workshop is required and
the timing is entirely coincidental. In any case, it’s by no means clear that
the workshop caused an improvement in Amalie’s self-esteem, and
a number of possible questions could focus on this ambiguity.
You’ll see numerous examples of causation along the way, but for now, keep
in mind that just because something precedes something else doesn’t mean that
the first necessarily caused the second, and just because two
things are correlated in some way doesn’t necessarily mean
they’re causally linked.
Essential Concept #3: Alternatives
Elwood Blues: What kind of music do you usually have here?
Bartender: Oh, we got both kinds—we got country and western!
Regardless of your opinion of country western music, it should be fairly
obvious that the bartender in this scene from the movie The Blues
Brothers suffers from an acute case of tunnel vision. The structure
of her statement—in particular, her use of the word
both—suggests that she believes there exist in the world only
two kinds of music. Your ability to recognize plausible alternative explanations
or possibilities that the author overlooks will help you with the various
question types.
You’ll soon see how recognizing alternatives leads directly to points.
Meanwhile, maintain a healthy skepticism. To treat the arguments in the Logical
Reasoning section as gospel is the kiss of death, considering how many of them
contain flaws and omissions and allow for alternative explanations or
possibilities. Keep your guard up, especially when an author states
unequivocally how something has to be. As the old, somewhat
sadistic saying goes, “There are many ways to skin a cat.” (Not that we can
figure out why anyone would want to.)
Essential Concept #4: Bait and Switch
Johnson: Due to an extreme aversion to the cold, Mr. Brown almost never ventures out of his apartment when the temperature feels below freezing to him. Since the thermometer I passed in the park yesterday read 31 degrees Fahrenheit, one degree below freezing, the person I briefly glimpsed at the other end of the park could not have been Mr. Brown.
There are actually two bait and switches in this argument: Evidence that
Brown “almost never” goes out under certain conditions is used to conclude that
the person Johnson spots “could not have been” Brown. This is a fairly common
bait and switch, featuring a mismatch in degree. The evidence better supports a
conclusion that the person glimpsed was probably not Brown, but
as stated the conclusion is too definitive to be drawn from the evidence
presented. That’s because “almost never” is not, in fact, the
same as “never.” If a question asked for the flaw in the reasoning, the answer
could read “the author treats a probable result as a definite result,” or
something along those lines. Noticing this bait and switch should make the
correct choice stand out.
But did you notice the other inconsistency between the first part of
Johnson’s argument and his conclusion? It’s a bit trickier and concerns the
difference between “the temperature feels below freezing to him” and “the
thermometer . . . read 31 degrees Fahrenheit.” First, we don’t know that the
thermometer is accurate; it would be better to explicitly state that it
was in fact 31 degrees. Even if we assume that it
definitely was just below the freezing point, we don’t know what actual
temperature feels below freezing to Brown. The “freezing”
element of the evidence does not match the way this element is presented in the
conclusion. Such switches en route from evidence to conclusion are notoriously
subtle, which is why we’re warning you about them up front.
You’ll see many cases such as this as we journey forward. And you’ll see
more of quirky Mr. Brown, as well, when we take up our discussion of Flaw
questions. Can’t wait until then? Not a problem—Johnson and Brown make a cameo
in the next Essential Concept, a little something we call
“unknowables.”
Essential Concept #5: Unknowables
There’s enormous pressure in our media-saturated society to be “in the
know”—that is, to be up on recent events lest we be considered, at best, behind
the times, or at worst a total fool. In the face of this expectation, we have a
tendency to pretend to possess knowledge we don’t actually have. Exploring this
phenomenon, a media critic once regaled fellow professors with bogus claims
supposedly reported in reputable journals. For example, he relayed the “widely
reported study” that proved that eating three chocolate éclairs a day would
actually make people lose weight—to which some of his overeager colleagues, in
an attempt to hide their shameful ignorance of said study, responded “Yeah, I
think I heard something like that . . .”
As far as the LSAT goes, a position of humility with respect to knowledge
is in order. While most exams you’ve taken in your life have tested
what you know—the capital of Wyoming, the twelfth president of
the United States, the atomic weight of helium, for example—the LSAT, to an
astounding degree, tests your power to recognize what you don’t
know. No standardized test is more interested in evaluating your ability to
comprehend the logical boundaries of statements and the limitations on
inferences derived from a set of facts. Again, this corresponds to the
requirements of legal study and practice, disciplines that highly prize a
capacity for recognizing the irrelevant and unknowable.
Logical Reasoning questions (as well as Reading Comprehension questions)
thus are littered with traps, wrong answer choices that are either irrelevant to
the passage or out-and-out unknowable based solely on the information given.
Later in the chapter you’ll learn to adopt an appropriate “don’t know, don’t
care” attitude toward such choices. Right now, let’s consider the case of Pepe’s
and Pablo’s eateries:
Pepe’s Café, located in the northeast corner of the Riverside Quadrangle, closed last July. The same month that Pepe’s Café closed, Pablo’s Cantina experienced a 7% increase in revenues compared to its revenues the previous month.
What don’t we know about this situation? Plenty.
Why did Pepe’s Café close? Who knows? Is Pablo’s Cantina in
the Riverside Quadrangle? In the same neighborhood as Pepe’s Café? In the same
state even? Does Pepe know Pablo? Are Pepe and Pablo even real people (and not
just brand names, for instance)? All unknowable. All excellent fodder for wrong
answer choices.
Just about the only thing we can deduce for sure from the
facts in the passage is that Pablo’s Cantina must have had higher revenues in
July than in June. Still, it’s mighty tempting to concoct our own scenarios. For
example, Pepe’s customers must have flocked to Pablo’s Cantina after Pepe’s
closed, right?—that would explain the rise in Pablo’s July revenues. No, that
could explain the rise. It’s certainly a reasonable
possibility, but there’s absolutely no evidence for it. Maybe it’s the other way
around—maybe Pablo’s successful month put the nail in Pepe’s coffin. Harking
back to the Amalie example, we have no way of knowing whether the two events
described are causally related. These events are correlated
because they happen to occur in the same month and both concern the performance
of restaurants, but that’s not nearly enough to determine that one was caused by
the other. If the author did conclude a causal connection, we would be wise to
recognize what we don’t know and envision alternatives.
Ah, but what about the increased revenue? Doesn’t this mean that Pablo’s
turned a greater profit in July than it did in June? Again, no way to tell—in
fact, this smacks of the old bait and switch discussed earlier, because
“revenue” does not equal “profit.” We know nothing about the expenses at Pablo’s
Cantina; maybe its increase in revenue resulted from a 50 percent increased
outlay for advertising and the restaurant is actually losing
money overall. Here, a good ear for bait and switches allows us to recognize
something we can’t possibly know and dismiss an unsupported inference out of
hand.
Want a bit more practice in not knowing stuff? Consider
again, if you will, the case of thin-blooded Brown in Essential Concept #4—we
can fill a canyon with all the things we don’t know about that
deal:
- Does Brown ever go to that park? DON’T KNOW.
- Do Brown and Johnson live near that park? Or near each other? Does Brown even know Johnson? DON’T KNOW, DON’T KNOW, DON’T KNOW.
- Does Brown go out in warm weather? DON’T KNOW—perhaps he’s a hermit and never goes out at all!
“That’s silly,” you might say. No, it’s not. It may be unfortunate,
unusual, even unbelievable, but it’s not illogical in the sense
that it doesn’t directly contradict any aspect of the stated situation. Think of
it this way: The fact that Noah never plays baseball in the winter does
not imply that he does play baseball in
the summer. The same applies to Mr. Brown. Go on, try it. It’s easy—you may even
surprise yourself with the depth of your ignorance regarding the Johnson/Brown
universe. Don’t get offended—it’s good ignorance,
useful ignorance, as long as you’re mindful of it.
Embrace the unknowable. When it comes to eliminating choices out of left
field (and there are plenty of those on the LSAT), the less you know, the
better—as long as you know what you don’t know.
Essential Concept #6: Loose Ends
A “loose end” is something that appears out of nowhere in the conclusion
or that appears in the evidence and disappears in the conclusion. Always be on
the lookout for aspects of the passage’s conclusion that are insufficiently or
ambiguously related to the evidence. Loose ends must be tied up in order for the
argument to work.
Loose ends in real life are pretty obvious; they’re things that make you
say, “Where did that come from?” Say, for example, your mother
calls and tells you that the New York Philharmonic is performing Mozart this
weekend, so your brother Brian will soon eat Chinese food. Your most likely
response would be “Okay, crazy lady—whatever . . . ” Obviously,
there’s at least one missing piece to this puzzle. Brian’s impending Chinese
feast comes out of nowhere and is therefore a loose end that needs to be tied
somehow to the Mozart concert for your mother’s statement to make sense. If you
cared enough to ask, you might find out that your brother goes to every Mozart
performance by the New York Philharmonic, and whenever he attends the
Philharmonic he makes a point to visit his favorite Chinese restaurant a few
blocks away. This, or some other kind of similar explanation, is necessary to
make your mother’s conclusion understandable based on the evidence she presents
for it.
Loose ends in LSAT Logical Reasoning arguments are more subtle, but the
same principle applies. Consider the following:
Virtue is not a self-sustaining attribute. To be considered virtuous, one must habitually display exemplary behavior not only in familiar but also in novel situations. Dede is virtuous, so she must be well disciplined.
Abstract concepts such as “virtue” and “discipline” may not be as easy to
grasp as Mozart and Chinese food, but if you look carefully the argument above
suffers from the same type of disjunction exhibited in the concert example. It
too contains a term in the conclusion (“well disciplined”) that appears out of
nowhere and needs to be tied in some way to what precedes it for the argument to
work. The habitual adherence to exemplary behavior may seem
like something that naturally requires discipline, but lacking an
explicit connection between these concepts, the argument is
incomplete. The test makers could ask what is assumed by the argument, in which
case the answer might be:
Habitually exhibiting exemplary behavior requires much discipline.
Or they could ask for something that weakens the argument, in which case
severing the tie between these concepts would suffice. Something along the lines
of:
Undisciplined people are often capable of habitually demonstrating exemplary behavior.
In both cases, the answer hinges on recognizing “well disciplined” as a
loose end that needs to be tied up for the argument to be complete.
You’ll get plenty of opportunities to spot loose ends in the pages to
come, as well as numerous chances to employ the other Essential Concepts we’ve
covered in this section.
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