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LOGICAL REASONING

By Alexander Smith,2014-08-29 10:20
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LOGICAL REASONING

    Logical Reasoning Bible

    解 题 思 路 整 理

    IPrimary Objectives:

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

    factual statements;

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

    the stimulus contains a fact set, examine each fact;

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

    weak;

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

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

    are automatically associated with certain question types;

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

    your answers to the question stem;

    7.Always read each of the five answers;

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

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

    9.If all 5 answers appear to be losers, return to the stimulus and reevaluate the

    argument.

    IIBasics of Logical Reasoning

    Premise IndicatorsCounter-Premise IndicatorsConclusion Indicatorsbecause, since, for, for But, yet however, on the thus, therefore, hence,

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

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

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

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

    we know this by, for this reason,

    furthermore, moreover,

    besides, in addition, what’s

    more, after all

    1

    Quantity IndicatorsProbability Indicators

    all, every, most, many, some, several, few, Must, will, always, not always, probably, sole, only, not all, nonelikely, would, not necessarily, could, rarely,

    never

    I题型

    Family #1Must Be or Prove Family

    1.Must Be True Questions

    Fact TestThe 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.Correct Answer TypesParaphrased answers, restating a

    portion of the stimulus in different

    terms.

    Combination answers, resulting

    from combining 2 or more

    statements in the stimulus.Incorrect Answer TypesCould Be True answers;

    Exaggerated answers;

    New Info;

    Shell Game;

    The Opposite answers;

    Reverse answers.

    2

2.Main Point Questions

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

    author’s 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 TestThe 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

    the answer is incorrect.

    3

    4.Method of Reasoning

    Method of Reasoning Questions TypesThe 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:

    New” Elements Answers;

    Half Right, Half Wrong;

    Exaggerated Answers;

    Opposite Answers;

    Reverse Answers.

    Method of Reasoning—Argument Part Method—AP questions often feature 2

    Questionconclusions—a main conclusion and

    subsidiary conclusion—where 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 Method—AP is to create wrong answers that describe parts of the argument other than the part named in the question stem.

    4

5.Flaw Questions

    Common Errors of Reasoning Explained

    a. Uncertain Use of a Term or Concepti. Appeal Fallacies

    Appeal to authority;

    Appeal to Popular Opinion/Appeal

    to Numbers;

    Appeal to Emotion.

    b. Source Argumentj. 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 Reasoningk. Exceptional Case/Overgeneralizationd. Errors of Conditional Reasoningl. Errors of Compositions and Division

    Mistaken Negation;以偏全或以全偏概概

    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.

    5

e. Mistaken Cause and Effectm. 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 Mann. 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 Evidencethe 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 Contradictionp. time shift errors

    6

    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 #2Help Family

    7.Strengthen Questions

    To effectively strengthen 3 Incorrect Answer TrapsTo strengthen a Cause and

    argumentsEffect 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.

    7

    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 FormulaThe following rules apply:

    Premise + Answer Choice = Conclusiona. 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

    correct answer;

    c. Elements that appear in the premises but

    not the conclusion normally appear in

    correct answer.

9.Assumption Questions

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

    Conclusion Assumption ValidTrue

    8

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Strengthen Causality题似?

    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.

    9

10.Paradox Questions

    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

    that do not quite meet the of the paradox;

    stated facts. These answers

    b. Similarities and are incorrect.

    differences.

    Family #3Hurt Family

    11.Weaken Questions

    Fundamental RulesCommon Weakening 3 Incorrect Answer Simple Rule for

    ScenarioTrapsweakening a

    conditional

    reasoninga. The stimulus will To weaken a Incomplete Opposite

    contain an argument;conditional info;answers;

    conclusion, attack b. Focus on the the necessary Improper Shell game

    conclusion;condition by comparison;answers;

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

    argument very

    carefully;

    d. Weak questions

    often yield strong

    prephrases;

    e. The answer

    choices are accepted

    as given, even if they

    include “New” info.

    10

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