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# LOGICAL REASONING

By Lauren Holmes,2014-08-25 16:37
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LOGICAL REASONING

Logical Reasoning Bible

I Primary Objectives:

?. Determine whether the stimulus contains an argument or if it is only a set of

factual statements;

?. If the stimulus contains an argument, identify the conclusion of the argument; If

the stimulus contains a fact set, examine each fact;

?. If the stimulus contains an argument, determine whether the argument is strong or

weak;

?. Read closely and know precisely what the author said. Do not generalize;

?. Carefully read and identify the question stem; Do not assume that certain words

are automatically associated with certain question types;

?. Prephrase; After reading the question stem, take a moment to mentally formulate

?. Separate the answer choice into contenders and losers; After completing this

process, review the contenders and decide which is the correct one;

argument.

II Basics of Logical Reasoning

Premise Indicators Counter-Premise Indicators Conclusion Indicators

because, since, for, for But, yet however, on the thus, therefore, hence,

example, for the reason that, other hand, admittedly, in consequently, as a result,

in that, given that, as contrast, although, even so, accordingly, clearly,

indicated by, due to, owing though, still, whereas, in must be that, shows that,

to, this can be seen from, spite of, despite, after all conclude that, follows that,

we know this by, for this reason,

furthermore, moreover,

more, after all

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Quantity Indicators Probability Indicators

all, every, most, many, some, several, few, Must, will, always, not always, probably, sole, only, not all, none likely, would, not necessarily, could,

rarely, never

I 题型

Family #1 Must Be or Prove Family

1. Must Be True Questions

Fact Test The correct answer to a Must Be True

question can always be proven by referring

to the facts stated in the stimulus.

You can often predict the occurrence of

Must Bu True questions because the

stimulus of most Must Be True questions

does not contain a conclusion.

portion of the stimulus in different

terms.

from combining 2 or more

statements in the stimulus.

; New Info;

; Shell Game;

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2. Main Point Questions

Many Main Point problems Main Point---Fill in the Incorrect Answer Types:

feature a structure that Blank Questions

a. Answers that are true but places the conclusion either

do not encapsulate the The blank is always at the at the beginning or in the

authors point; end of the stimulus. There is middle of the stimulus.

a conclusion indicator at the

b. Answers that repeat start of the sentence to help

premises of the argument. you recognized that are

being asked to fill in the

conclusion of the argument.

3. Point at Issue

Incorrect Answers in Point a. Ethical versus Factual Situations;

at Issue Questions

b. Dual Agreement or Dual Disagreement;

c. The View of 1 Speaker is Unknown.

The Agree/Disagree Test The correct answer must produce responses where one

speaker would say I agree, the statement is correct and

the other speaker would say I disagree, the statement is

incorrect. If those two responses are not produced, then

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4. Method of Reasoning

Method of Reasoning Questions Types The stimulus for a Method of Reasoning question will contain an argument, and the

argument can contain either valid or invalid reasoning.

You must watch for the presence of the premise and conclusion indicators.

Use Fact Test to eliminate answers. If an answer choice describes an event that did not occur in the stimulus, then that answer

is incorrect.

Several types of incorrect questions:

; Half Right, Half Wrong;

Method of ReasoningArgument Part MethodAP questions often feature 2

Question conclusionsa main conclusion and

subsidiary conclusionwhere the main

conclusion is typically placed in the first or second sentence and the last sentence

contains the subsidiary conclusion.

Trick: the test makers in MethodAP is to

create wrong answers that describe parts of

the argument other than the part named in the question stem.

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5. Flaw Questions

Common Errors of Reasoning Explained

a. Uncertain Use of a Term or Concept i. Appeal Fallacies

; Appeal to authority;

; Appeal to Popular Opinion/Appeal

to Numbers;

; Appeal to Emotion.

b. Source Argument j. Survey Errors

ad hominem, or attack the person (or ; Survey uses a biased sample; source)

; Survey questions are improperly

; Focusing on the motives of the constructed;

source;

; Respondents to the survey give

; Focusing on the actions of the inaccurate responses.

source.

c. Circular Reasoning k. Exceptional Case/Overgeneralization d. Errors of Conditional Reasoning l. Errors of Compositions and Division

; Mistaken Negation; 以偏概全或以全概偏

; Mistaken Reversal;

; Confuse a necessary condition

for a sufficient condition;

; Confuse a sufficient condition

with a required condition.

If you identify a stimulus with conditional reasoning and are asked a Flaw question, you can quickly scan the answers for the one answer that contains Sufficient, Necessary or both.

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e. Mistaken Cause and Effect m. False Analogy

; Assuming a causal relationship

on the basis of the sequence of

events;

; Assuming a causal relationship

when only a correlation exists;

; Failure to consider an alternate

cause for the effect, or an

alternate cause for both the cause

and the effect;

; Failure to consider that the events

may be reversed.

If you identify a stimulus with causal reasoning and are asked a Flaw question, quickly scan the answers for one that contains Cause, Effect or both.

f. Straw Man n. False Dilemma

Ignore the actual statements made by the opposing speaker and instead distorts and

refashions the argument.

g. General Lack of Relevant Evidence of o. Errors in the Use of Evidence

the Conclusion

; Lack of evidence for a position is

taken to prove that position is false;

; Lack of evidence against a position

is taken to prove that position is

true.

; Some evidence against a position is

taken to prove that position is false;

; Some evidence for a position is

taken to prove that position is true. h. Internal Contradiction p. time shift errors

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q. Numbers and Percentages Errors.

Author improperly equates a percentage

with a definite quantity, or when an author

uses quantity info to make a judgment

about the percentage represented by that

quantity.

6. Parallel Questions

The question stem for any Parallel question reveals whether the stimulus contains valid or

invalid reasoning. If the question stem mentions a flaw, then the reasoning is invalid. If

the question stem does not mention a flaw, then the reasoning is valid. The following elements do a. Topic of the stimulus;

not need to be paralleled:

b. The order of the presentation of the premises and

conclusions in the stimulus.

You must parallel all of a. The Method of Reasoning;

these elements:

b. The Validity of the Argument;

c. The Conclusion;

d. The Premises.

If all else fails, Create a short statement that summarizes the action in

the argument. Then take the abstraction and compare it to

each argument.

Family #2 Help Family

7. Strengthen Questions

To effectively strengthen 3 Incorrect Answer Traps To strengthen a Cause and arguments Effect relationship

Identify the conclusion; Eliminate any alternate ; Opposite answers;

causes;

Personalize the argument; ; Shell game answers;

Show that when the cause Look for weakness or holes occurs, the effect occurs; ; Out of scope

in the argument.

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answers. Show that when the cause

does not occur, the effect

does not occur;

Eliminate the possibility

that the stated relationship

is reversed;

Show that the data used to

make the causal statement is

accurate, or eliminate

possible problems with the

data.

8. Justify Questions

Justify Formula The following rules apply:

Premise + Answer Choice = Conclusion a. Any “New element in the conclusion

will appear in the correct answer;

b. Elements that are common to the

conclusion and at least 1 premise, or to 2

premises, normally do not appear in the

c. Elements that appear in the premises but

not the conclusion normally appear in

9. Assumption Questions

The relationship between the conclusion and the assumption can be described as:

Assumption Conclusion ValidTrue

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Supporter/Defender Assumption Model

Supporter Assumption: These assumptions link together new or rogue elements in the stimulus or fill logical gaps in the argument.

Defender Assumption: These assumptions statements that eliminate ideas or assertions

that would undermine the conclusion.

If there is no obvious weakness in the argument and you are faced with an Assumption question, expect to see a Defender answer choice.

Assumption Negation Technique:

a. logically negate the answer choices under consideration;

b. the negated answer choice that attacks the argument will be the correct answer.

3 Quirks of Assumption Question Answer Choice:

a. Watch of answers starting with the phase at lease one or at least some;

b. Avoid answers that claim an idea was the most important consideration for the author;

c. Watch for the use of not or negatives in assumption answer choices.

Assumptions and Conditionality:

a. If conditional statements are linked together in the argument, the correct answer choice for an Assumption question will typically supply a missing link in the chain;

b. If no conditional chains are present and only a conditional conclusion exists, the

correct answer will usually deny scenarios where the sufficient condition occurs and the

necessary does not, or it works as a Defender.

Assumption and Causality: 解题思路与Strengthen Causality类似

a. Eliminate any alternate causes;

b. Show that when the cause occurs, the effect occurs;

c. Show that when the cause does not occur, the effect does not occur;

d. Eliminate the possibility that the stated relationship is reversed;

e. Show that the data used to make the causal statement is accurate, or eliminate possible

problems with the data.

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The correct answer will The following types of Note: You must address the allow 2 sides to be factually answers are incorrect: facts of the situation. Many correct. answers will try to lure you

; explain only 1 side with reasonable solutions

of the paradox; that do not quite meet the

; b. Similarities and are incorrect.

differences.

Family #3 Hurt Family

11. Weaken Questions

Fundamental Rules Common Weakening 3 Incorrect Answer Simple Rule for

Scenario Traps weakening a

conditional

reasoning

a. The stimulus will To weaken a ; Incomplete ; Opposite

argument; conclusion, attack

; Improper ; Shell game the necessary b. Focus on the comparison; answers; condition by conclusion; showing that the

; Qualified ; Out of scope necessary c. The info in the conclusion. answers. condition does not stimulus is suspect. need to occur in There are often order for the reasoning errors sufficient present, and you condition to occur. must read the

argument very

carefully;

d. Weak questions

often yield strong

prephrases;

choices are accepted

as given, even if

they include New

info.

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