The anatomy of an argument

What a Logical Reasoning question looks like

Half of your scored LSAT is Logical Reasoning: two sections of short passages, each followed by one question (occasionally two). LSAC says the section measures your ability to examine, analyze and critically evaluate arguments as they occur in ordinary language, in passages drawn from newspapers, magazines, scholarly writing, advertisements and informal discussion (LSAC, Logical Reasoning). Each question has five answer choices, and the directions ask for the best one: the choice that most accurately and completely answers the question (LSAC, Logical Reasoning Sample Questions).

Every Logical Reasoning question has three parts:

1. The stimulus: a short passage, usually an argument, sometimes a set of facts or a dialogue.
2. The question stem: what you must do with it (find the conclusion, find an assumption, find a flaw…).
3. Five choices, of which one is best.

Before any of that can work, you need the skill LSAC lists first: recognizing the parts of an argument and how they relate. That is this lesson.

Premises and conclusions

An argument is a set of claims in which some claims (the premises) are offered as reasons to believe another claim (the conclusion).

The town should move its summer concerts to the riverside park. The square where they are held now floods in heavy rain, and three of last year's eight concerts were cancelled for that reason.

• Premise: the square floods in heavy rain.
• Premise: three of eight concerts were cancelled because of flooding.
• Conclusion: the town should move the concerts to the riverside park.

Notice that the conclusion came first. On the LSAT the conclusion can sit anywhere: first, last, or buried in the middle of a sentence. Position tells you nothing; function tells you everything.

The "why should I believe that?" test

For each claim, ask: does anything else in the passage support this? and does this support anything else?

• A claim that is supported but supports nothing further is the main conclusion.
• A claim that supports something and is not itself supported is a premise.
• A claim that is supported and supports the main conclusion is an intermediate conclusion (also called a subsidiary conclusion).

A useful check: put the claims in the order "[premise], therefore [conclusion]". If the sentence reads naturally, you have the direction right. "The square floods, therefore the concerts should move" makes sense; "The concerts should move, therefore the square floods" does not.

Indicator words

Certain words announce a claim's role. They are helpful, but they are clues, not proof.

Kind	Common indicator words
Conclusion indicators	therefore, thus, hence, so, consequently, it follows that, accordingly, which shows that, we can conclude that
Premise indicators	because, since, for, given that, after all, as shown by, in view of the fact that
Contrast (often introducing the author's own view)	but, however, yet, nevertheless, still, although (the clause after although is usually conceded, not argued for)
Opposing view	some argue that, critics claim, it is often said, many believe, according to the council

Two cautions:

• "So" and "thus" can mark an intermediate conclusion, not the main one.
• Many arguments have no indicators at all. Then the "why should I believe that?" test does the work.

The other things a stimulus contains

Real arguments carry extra material. Learn to label it.

• Background: facts that set the scene but are not offered as reasons. ("The festival began in 1998.")
• A concession: something the author admits that seems to cut the other way. ("Admittedly, the park has less parking.") The concession is not the conclusion; the author grants it and argues past it.
• An opposing view: a position the author describes in order to reject it. ("Some council members say the square is part of the town's identity.") The rejection, not the view, is usually the main conclusion.
• An example: a specific case offered in support of a general claim.

Worked example 1: the conclusion in the middle

Many readers assume that the novelist Ilse Varga wrote quickly, because she published eleven novels in fourteen years. Her recently opened letters, however, show that she drafted each novel over a period of six or seven years, working on several at once. The common assumption about her working habits is therefore mistaken.

Labels:

• "Many readers assume that Varga wrote quickly…": an opposing view, with the reason its holders give (eleven novels in fourteen years).
• "Her letters show she drafted each novel over six or seven years": the premise.
• "The common assumption… is therefore mistaken": the main conclusion.

Which one of the following most accurately expresses the main conclusion of the argument?

• A. Ilse Varga published eleven novels in fourteen years.
• B. Varga's letters show that she worked on several novels at once.
• C. Readers who think Varga wrote quickly are wrong about her working habits.
• D. Novelists who publish many books usually work on several at a time.
• E. Varga's letters are a more reliable source than her publication record.

Answer: C. It restates the main conclusion, that the common assumption is mistaken. A is the evidence for the view the author rejects. B is the author's premise. D generalizes to all novelists, which the passage never does. E may be implied by the reasoning, but it is not what the argument sets out to establish.

Worked example 2: an intermediate conclusion

The water authority's plan to replace the old pipes on Linden Street should be approved. Those pipes are made of a material known to corrode quickly, so they are likely to fail within the decade. A failure on Linden Street would cut water to the hospital.

Run the test:

• "The pipes are made of a fast-corroding material" supports →
• "they are likely to fail within the decade", which, together with "a failure would cut water to the hospital", supports →
• "the plan should be approved".

"They are likely to fail within the decade" is an intermediate conclusion: supported by the material, and in turn supporting the recommendation. The word so introduced it, which shows why "so" does not always mark the main conclusion.

A choice saying "The Linden Street pipes are likely to fail within the decade" would be a trap on a main-conclusion question: it is a conclusion, but not the main one.

Worked example 3: a concession and no indicators

Admittedly, a four-day school week would save the district money on buses and heating. The district's own survey found that most working parents could not arrange care for a fifth weekday. A plan that saves money while leaving young children without supervision is not a sensible plan.

There is no "therefore". Ask what the author is trying to get us to accept. The first sentence is a concession (signalled by "admittedly"). The survey result is a premise. The last sentence is the conclusion, stated as a general judgment that clearly applies to the four-day week. A good answer would read: "The four-day school week is not a sensible plan." A choice that says "A four-day week would save the district money" picks the concession, the opposite of the author's point.

Statements that are not arguments

Sometimes a stimulus offers facts with no conclusion:

In the survey, 40 percent of respondents walked to work. Of those, most lived within two kilometres of their workplace.

Nothing here is offered as a reason for anything else. These stimuli come with questions that ask what can be inferred from the facts, which you will meet in Inferences: must be true and best supported. Recognizing that a passage is not an argument tells you not to hunt for a conclusion that isn't there.

How to answer a main-conclusion question

1. Read the stem first so you know you are hunting for the main conclusion.
2. Label each sentence: premise, conclusion, background, concession, opposing view.
3. Apply the test: which claim does everything else support?
4. Predict in your own words, then find the choice that matches its meaning, not its wording.
5. Check strength and scope. If the author says "probably", the right answer should not say "certainly". If the author speaks of one district, the answer should not speak of all districts.

The four classic traps

Trap	What it looks like	Why it's wrong
A premise	A choice that repeats a fact from the stimulus	It is a reason, not the claim the reasons support
An intermediate conclusion	A supported claim that is still a step on the way	It supports something further
The opposing view	The claim the author describes in order to reject it	It is the opposite of the author's point
An overreach	The right idea, stated too broadly or too strongly	The author claimed less

LSAC's own advice applies throughout: a choice can be true and still not answer the question (LSAC, Suggested Approach for Logical Reasoning). On a main-conclusion question, premises are usually true; they are still wrong answers.

Check yourself

• What makes a claim the main conclusion rather than an intermediate conclusion?
• Why can't you rely on position (first or last sentence) to find the conclusion?
• How do you treat the sentence after "admittedly" or "although"?
• When a passage describes what "some critics claim", what is the author usually doing with that claim?
• Why is a true premise a wrong answer to a main-conclusion question?