Part I - Introducing LSAT Logical Reasoning :: The Terrain

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The Format Of Logical Reasoning

Logical Reasoning consists of two of the four scored sections on the LSAT. Each section will have approximately twenty-five questions.

Nature Of The Stimulus – Mostly Arguments

Most of the questions are based on "arguments". What is the definition of "argument" that is used by LSAT? According to LSAT arguments are: "… sets of statements that present evidence and draw a conclusion based on that evidence."

Now, a bit of vocabulary:

Premises: The set of statements that present evidence, which are offered as justification for the conclusion, are called "premises".

The language of "Premise Indicators":

Words like "because", "since", "for the reason that", etc., do indicate justification. For that reason they are often indicative of "premises".

On the LSAT, all "premises" are offered as being true. There is no attempt to justify or support them. Hence, when answering LSAT questions, you just assume that premises are true.

Conclusion: The main point – the position that the "premises" are in support of is called the "conclusion".

The language of "Conclusion Indicators":

Words like "hence", "therefore", "thus", "it follows that", etc., indicate a "conclusion". For this reason they are often "conclusion indicators".

(A word of caution: since arguments can have multiple conclusions, a "conclusion indicator" may not be an indicator of the main conclusion! Please read carefully.)

In contrast to "premises", "conclusions" are not assumed to be true. They are offered as being somehow justified by the "premises".

Getting A Bit Ahead Of Ourselves For The Moment – Two Additional Points About "Premises" and "Conclusions"

First – it is a mistake to think that the "conclusion" or "premises" appear in any particular location in an argument. For example, although the "conclusion" is often at the end, it doesn’t have to be.

Second – arguments may have more than one conclusion. The first conclusion may actually operate as the a premise for a second conclusion.

The extent to which the "premises" justify the "conclusion", is NOT ASSUMED, but is open to challenge. It is the analysis of the relationship between the premises and the conclusion that is at the heart of most of these questions. LSAT calls this the process of evaluating:

"How The Argument Goes". Part II - What Are You Asked To Do With The Arguments? Determine "How The Argument Goes"

"Once you have identified the premises and the conclusion, the next is to get clear about exactly how the argument is meant to go; that is, how the grounds offered for the conclusion are actually supposed to bear on the conclusion. Understanding how the argument goes is a crucial step in answering many questions that appear on the LSAT. This includes questions that ask you to identify a reasoning technique used within an argument, questions that require you to match the patterning of reasoning used in two separate arguments and a variety of other question types.

Determining how the argument goes involves discerning how the premises are supposed to support the overall conclusion."

• page 16 "The Official LSAT SuperPrep."

You will notice that this is very non-technical language. That is deliberate. LSAT cannot use language that would require a specific academic background to understand.

How The Argument Goes – A Three Dimensional Analysis

Dimension 1: The Argument or Passage;

Dimension 2: The Questions;

Dimension 3: The Answer Choices

Every question involves analyzing the interplay among these three dimensions.

Dimension 1: LSAT Logical Reasoning Arguments – What Are They About?

Most of the questions are based on arguments. An argument always has a conclusion which is justified because of one or more premise(s). When you read the argument ask:

  1. What is the main point/conclusion that is being made?
  2. Exactly how far does that main point/conclusion go? What is the subject of that main point (beware of answer choices that are too broad or too narrow)? What exactly is being said about that subject (again beware of answer choices that are too broad or too narrow).
  3. What is the justification/premise for the conclusion? How does that premise support or bear on the conclusion?

In summary: when you read the argument simply ask: What is being said and why?

Arguments or Passage – The Basic Skills

If it is an argument – you must be able to:

  • locate the conclusion and understand the exact scope of what the conclusion is saying. What is the exact conclusion being made? What is the position that is being taken? How far does that conclusion or position go?
  • Identify the premise (which is the justification for the conclusion). The basic structure of an argument is: Conclusion, "because/since/for the reason" that premise.
  • Understand exactly how the premise is supposed to support the conclusion
  • Separate information in the text that is "background context" from the information that collectively is the premise and conclusion.

If the passage is NOT an argument you must be able to understand the primary purpose/main point of the passage.

Dimension 2: LSAT Logical Reasoning Questions – What Are They About? Question Types vs. Question Groups

For each question type you must understand what exactly you are being asked to do. (This does not mean that you must put the argument into a specific category.) In other words, what aspect of "how the argument goes" are you asked to respond to?

There are many different Logical Reasoning question types. It is always easier to think in terms of smaller groups than larger groups. The large number of questions types can be broken into a smaller number of question groups.

Although there is considerable overlap, the vast majority of the actual LSAT questions fall into one of five groups.

Group 1 – Objective Description

These questions will ask you to identify:

  • the method or reasoning used in arguments; or
  • the pattern of reasoning used in arguments (parallel reasoning);
  • matching and identification of argument flaws;
  • questions that ask you to identify what the conclusion of the argument actually is;
  • questions that ask you to identify points on which disputants hold the same or conflicting points of view;

Group 1 questions ask you to identify objective aspects of the argument but do not require you to make a judgement about its persuasive value.

Group 2 – Effectiveness And Persuasiveness – Questions That Ask You To Identify What Would Make The Argument More Or Less Persuasive

These questions will ask you to assess:

  • what additional information would make the argument more or less persuasive (strengthen or weaken how the premises bear on the conclusion). These questions usually do NOT ask what would guarantee that the conclusion would follow from the premises.

Group 2 questions will require you to assess the persuasive value of the argument. They often use the language "strengthen" or "weaken" the above argument? They are related to Group 4 questions, which often use the language of "assumptions".

Group 3 – Questions That Ask You To Determine What Follows From The Argument Or Passage

These questions will ask you to determine:

  • what further inferences can be made from the passage or argument (note that the strength of the inference is important. Are you asked to determine: what ALWAYS follows from, what SOMETIMES follows from or what NEVER follows from).
  • the applicability of "sufficient" vs. "necessary" conditions. (These topics are tied heavily into the analysis of conditional reasoning.)

Group 3 questions may or not be based on arguments.

Group 4 – Questions That Ask You To Identify What Additional Information/Premise Plays A Role In Ensuring The Conclusion Must From The Premise(s)

These questions will ask you to:

  • identify the REQUIRED missing premise: the premise that must be added to guarantee that the conclusion MUST be true;
  • identify a premise, that although NOT REQUIRED would be a GUARANTEE that the conclusion would follow

Group 4 questions are related to Group 2 questions but will be use the language of "assumptions". Group 2 questions often use the language of "strengthen" or "weaken".

Group 5 – Questions That Ask About Principles

These questions will ask you to:

  • identify a principle that will govern a situation;
  • apply an existing principle to a given situation.

Dimension 3: LSAT Logical Reasoning Answer Choices – What Are They About?

This is where the action is. The LSAT is multiple-choice. Your job is to recognise or identify the answer. LSAT will not make this easy. In fact, the job of LSAT is to:

"Attract you to answer choices that are wrong, and repel you from answer choices that are right!"

To facilitate this goal, LSAT has developed a large number of disguises. Some of these disguises are based on content, some are based on application and some are based on format. What follows are some comments on each:

Content Based Disguises – Some Examples:

  • answer choices that include too much or too little;
  • answer choices that require meeting multiple conditions when not all of the conditions are met

Format Based Disguises – Some Examples:

  • the order of the answer choices – attractive wrong answer distracters appearing before the right answer;
  • the ordering of information in a specific answer choice – putting irrelevant information before the part of the answer choice that matters.

Application Based Disguises – Some Explanation:

In my experience theses are by far the hardest for students to see. When reading an answer choice, you must go read the language of the answer choice very carefully. But, you must go well beyond that careful reading.

Ask yourself: if the information in this answer choice were true, how would that affect the answer to the question being asked!

Our Tutorial Series has been designed to explore may of these topics.

To learn about our new "LSAT Logic Course"

To learn about our full-length LSAT Preparation Courses

Copyright © John Richardson 2006, 2007, 2008 all rights reserved.