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-Evidence. Unknown assumption----> conclusion
-unstated premise. what must be true in order for the argument to be true.
-Ask you to identify an assumption of the author's argument.
EX: Which one of following is an assumption required by the argument above
Logical Reasoning Primary Objectives:
Determine whether the stimulus contains an argument or if it is only a set of factual statements.
a fact, proposition, or statement from which a conclusion is made. A premise gives a reason why something should be believed. Premises support and explain the conclusion and give reasons why the conclusion should be accepted.
a statement or judgment that follows from one or more reasons. A conclusion is the point the author tries to prove by using another statement. Draw from and rest on premises.
something must be true.
1. Must be true/most supported:
Identify the answer choice that is best proven by the information in the stimulus
EX: If the statements above are true, which one of the following must also be true?
EX: Which one of the following can be properly inferred from the passage?
Find the primary conclusion
EX: The main point of the argument is
3. Point at issue/point of agreement:
Identify a point of contention between two speakers and thus these questions appear almost exclusively with two-speaker stimuli.
EX: John and Jones disagree about whether
5. Justify the conclusion:
Justify the conclusion questions ask you to supply a piece of information that, when added to the premises, proves the conclusion.
EX: which one of the following, if assumed, allows the conclusion above to be properly drawn?
Attack or undermine the author's argument.
EX: which one of the following, if true, most seriously weakens the argument?
-Resolve the paradox
Every resolve the paradox question stimulus contains a discrepancy or seeming contradiction. Find the answer choice that best resolves the situation.
EX: which one of the following, if true, would most effectively resolve the apparent paradox above?
Select the answer choice that provides support for the author's argument or strengthens it in some way
EX: which one of the following, if true, most strengthens the argument?
9. Method of reasoning:
Describe in abstract terms the way the author made his or her argument.
EX: which one of the following describes the technique of reasoning used above?
12. Evaluate the argument:
Decide which answer choice will allow you to determine the logical validity of the argument.
EX: the answer to which one of the following questions would contribute most to an evaluation of the argument?
11. Parallel reasoning/parallel flaw:
Identify the answer choice that contains reasoning most similar in structure to the reasoning presented in the stimulus.
EX: which one of the following arguments is most similar in its pattern of reasoning to the argument above
Flaw in the reasoning:
Describe in abstract terms, the error of reasoning committed by the author.
EX: the reasoning in the mayor's argument is flawed because this argument
The correct answer to a Must Be True Question can always be proven by referring to the facts stated in the stimulus.
4. Shell Game
INCORRECT ANSWER DECEPTION
An idea or concept is raised in the stimulus and then a similar idea is an answer choice but the idea is changed enough to be incorrect.
Two Incorrect Answers Types:
1. Answers that are true but do not encapsulate the author's point
Answers that repeat the premises of the argument
Always points to the conclusion. Always a conclusion signifier then the blank at the end:
"Hence, in many cases, by criminals' characterization of their circumstances____"
And you fill in with the conclusion
**Main point IS the Conclusion
-A sufficient condition
can be defined as an event or circumstance whose occurrence indicates that a necessary condition must also occur.
"If someone gets an A on an exam, then they must have studied for the exam."
A+ --------> Study
Be wary of Causal Reasoning: the sufficient condition does not make the necessary condition occur.
-A necessary condition
can be defined as an event or circumstance whose occurrence is required in order for a sufficient condition to occur
A > S
Contrapositive: ~S > ~A
-Every original statement that is true can create a true contrapositive that is important for most games
Sufficient Condition Signals
In order to
Necessary Condition Signals
Unless*: whatever term is modified by unless, except, until becomes the necessary condition
Conditional Reasoning stimulus and Must be True question stem =
look for repeat and contrapositive in answer choices
"At least one of the two" possibly both on the LSAT
"Either Jack or Ron will attend the party"
~J > R or ~R > J
"If you are rich or famous then you are happy"
R or F > H
Contrap: ~H > ~ R or H
If Gomez runs for president, then Hong will not run for president.
G > ~H
Contrap: H > ~G
When you have conditional reasoning in the stimulus and a Weaken question,
immediately look for an answer that attacks the necessary condition
Cause and effect relationships must
show that the cause MADE the effect occur.
1) Chronology of two events
a. Doesn't require the one to cause the other just because close in order
b. Post hoc ergo propter hoc
2) Connection between events is different
Could be a conditional relationship not a causal one
If the causal statement is the conclusion, then the reasoning is flawed.
To not make this mistake, always identify the conclusion and identify where a causal relationship occurs if there is one and what function in the argument it plays
Premise: in N. america, people drink a lot of milk.
Premise: There is a lot of cancer in N. america.
Conclusion: Therefore, drinking milk causes cancer.
How to attack a Causal Conclusion:
A. Find an alternate cause for the stated effect
B. Show that even when the cause occurs, the effect does not occur
C. Show that although the effect occurs, the cause did not occur
D. Show that the stated relationship is reversed
E. Show that a statistical problem exists with the data used to make the causal statement
Smoking causes cancer. = S--> C
Solving Justify the Conclusion Questions Mechanically:
1. Any "new" element in the conclusion will appear in the correct answer choice
2. Elements that are common in the conclusion and at least one premise normally do not appear in the correct answer
a. If an element is in both the conclusion and premises then the bridge is already established and doesn't need justified.
b. Elements that appear in the premises but not the conclusion usually appear in the correct answer
**Link new elements in the premises and conclusion
and ignore common elements to both
Conclusionvalid ---> AssumptionTrue
-Assumption answer choices cannot contain extraneous information
-The correct answer to assumption questions is a statement the author must believe in order for the conclusion to make sense
-The stem usually uses the words assume, presuppose
-The stem never uses IF or conditional indicators
-Supporter assumptions: link together new or rogue elements in the stimulus or fill logical gaps in the argument
EX: All male citizens of Athens had the right to vote. Therefore, Socrates had the right to vote in Athens.
(linking assumption: Socrates was a male in Athens.)
-This linking assumption is a supporter that resembles a justify the conclusion.
protect the argument by eliminating ideas that could weaken the argument
EX: People who read a lot are more intelligent than other people. Thus, reading must cause a person to be intelligent.
Double-Check Answers with Assumption Questions:
1. Logically negate the answer choices under consideration
2. The negated answer choice that attacked the argument will be the correct answer
Assumption Answer Choices Quirks:
1. Watch for answers starting with the phrase at least one, or at least some
a. If the answer starts with either phrase, the answer is often correct
2. Avoid answers that claim an idea was the most important consideration for the author
a. "primary purpose, top priority, main factor" etc are wrong
3. Watch for use of not or other negatives
These answer choices are often right, because the test makers assume it is more difficult to identify.
resolve the paradox
A similarity cannot explain a difference; a difference cannot explain a similarity
Additive v. Inherent Logic
Additive is often the correct answer choice. A--> B <---> C you can connect A to C through B and drop B. That is additive.
Inherent follow from a single statement: A --> B and are true based only on that relationship
Contrapositives are examples of inherent inferences.
Reversible Relationships: Non-Reversible Relationships:
3. Uncertain use of a term or concept: Equivocation
a. Using the same term in different ways is confusing and undermines the argument
Both in stimulus and in answer options, look for shifting interpretation of words
4. Source Argument: Ad Hominem
a. Attacks the person or source before or rather than the argument
Focus on motives or actions of the source
5. Circular Reasoning:
a. Author assumes as true what is supposed to be proven
cause and effect
a. Assuming a causal relationship on the basis of the sequence of events
b. Post Hoc Ergo Propter Hoc
c. Assuming a causal relationship when only correlation exists
d. Failure to consider alternate causes for the effect or for the cause and effect
e. Failure to consider the events may be reversed
f. Look for "cause" and "effect" words in answer choices with a conditional flaw question and you've usually got the right answer
6. Errors of Conditional Reasoning:
a. Mistaken Negation, Mistaken Reversal
b. Confuses the sufficient condition with the necessary condition
c. Confuses the necessary condition with the sufficient condition
d. Look for "sufficient" and "necessary" words in answer choices with a conditional flaw question and you've usually got the right answer
a. Author attacks an opponent's position by ignoring the actual statements and instead distorts and refashions the argument into something weaker and easier to defeat
9. General Lack of Evidence for the Conclusion:
a. Misuse information to such a degree that it fails to provide any information to support the conclusion or only provides irrelevant information
10. Internal Contradiction:
a. self-contradiction is when the author makes conflicting statements
11. Appeal Fallacies:
a. Appeal to authority:
i. Uses the opinion of an authority to attempt to persuade the reader to value the authority's opinion
b. Appeal to popular opinion/numbers/bandwagon:
i. A position is true because the majority believes it
c. Appeal to Emotion:
i. Emotions or emotionally-charged language is used to persuade the reader
12. Survey Errors:
a. Invalid if:
i. Uses a biased sample
ii. The questions are improperly constructed
iii. Respondents gave inaccurate answers
13. Exceptional Case/Overgeneralization:
a. Small number of instances are treated as if they support a broad conclusion
14. Errors of composition and division:
a. Composition: attributes a characteristic of part of the group to the whole or to each in a group
b. Division: author attributes a characteristic of the whole to a part of the group
a. Author uses an analogy that is too dissimilar to the original situation to be applicable
Fallacy of limited options
a. Claims that only two courses of action are available when there may be others
17. Errors in the Use of Evidence:
a. Lack of evidence for a position is taken to prove that the position is false
b. Lack of evidence against a position is taken to prove that position is true
c. Some evidence against a position is taken to prove that position is false
d. Some evidence for a position is taken to prove that position is true
18. Time Shift Errors
a. Assuming conditions will remain constant over time, and that what was the case in the past will be the case in the present or future
19. Numbers or % Errors
a. Author improperly equates a percentage with a definite quantity or uses quantity info to make a judgment about the % represented by the quantity
What to Parallel in Answer:
1. The method of reasoning
a. Causal or conditional reasoning
2. The validity of the argument
a. If the stimulus is valid reasoning, eliminate answers with invalid reasoning
b. If the stimulus has invalid reasoning, eliminate answers with valid reasoning
3. The conclusion
a. Match the certainty level or intent
b. Match absolutes from stimulus with answers: must, always, never, should
4. The premises
a. Match words/absolutes from premises in stimulus with premises in answers
numbers/ percents words
Words to introduce #: Words to Introduce %:
General Rules for Must be True questions with amounts:
1. If the stimulus contains percent or proportions only, avoid answers that contain hard numbers [answer will talk only of percent(s) or proportions]
2. If the stimulus contains only numbers, avoid answers that contain percent or proportions
If the stimulus contains both percents and numbers, any choice that contains numbers, percent, or both may be true
#and % misconceptions
Misconception #1: increasing percentages automatically leads to increasing numbers
If a percent becomes larger the number that corresponds does NOT necessarily have to get larger too
EX: "auto manufacturer X increased their US market share 10% last year to 25% this year. Therefore, Company X sold more cars in the US this year than last."
If the total cars sold decreased enough their share could go up % wise but down in real numbers
# and % misconceptions cont.
Misconception #4: decreasing numbers automatically leads to decreasing percentages
Misconception #5: large numbers automatically mean large percentages, and small numbers automatically mean small percentages
Misconception #6: large percentages automatically mean large numbers, and small percentages automatically mean small numbers
# and % misconceptions continued
Misconception #2: decreasing percentages automatically leads to decreasing numbers
Misconception #3: increasing numbers automatically leads to increasing percentages
EX: the number of bicycle deaths rose dramatically from last month to this month. Therefore, bicycle deaths must make up a greater percentage of all road accidents this month.
~Not true if the total number of accidents dramatically increased as well as the increase in bicycle deaths
evaluate the argument questions
1. The information in the stimulus is suspect, so you should search for the reasoning error present
2. The answer choices are accepted as given, even if they include "new" information. Your task is to determine which answer choice best helps determine the validity of the argument.
the variance test
ONLY for Evaluate the Argument Questions:
Supply two polar opposite responses to the question posed in the answer choice and the analyze how the varying responses affect the conclusion in the stimulus [only use once you've narrowed down the answers to one or two]
CANNOT be true
1. Accept the stimulus information and use only it to prove that one of the answer choices cannot occur.
2. If an answer choice contains information that does not appear directly in the stimulus or as the result of a combination of items in the stimulus, then that answer choice could be true and is incorrect. The correct answer choice will directly disagree with the stimulus or a consequence of the stimulus.
Cannot be True cont
Polar Opposite "must be true" questions" or "reverse Weaken questions"
The stimuli in cannot be true questions rarely contains a conclusion, so don't need to assess an argument, just focus on facts at hand
Will either state "CANNOT be true" or "could be true EXCEPT" or "Must be false"
1. Cannot be true #% questions:
-the stimulus will often supply enough info for you to determine that certain outcomes must occur [i.e. increasing market share while the overall market size remains constant results in greater sales]. The correct answer then violates this outcome.
2. Cannot be true Conditional statements:
a. CANNOT occur: the sufficient condition occurs, and the necessary condition does not occur.
b. When a conditional statement is made in a cannot be true question, actively seek the answer that matches the above scenario
Incorrect answers often play upon the possibility that necessary condition occurs but the sufficient does not. These could occur and are thus incorrect.
point @ issue Qs
To find the correct answer:
Examine the conclusion of each speaker
point at issue Common Incorrect answers:
1. Ethical v. factual situations:
a. Stimulus addresses ethics; then answer choices that are factual in nature cannot be correct.
b. When stimulus addresses facts; answer choices that are ethical cannot be correct
2. Dual Agreement or Dual Disagreement:
a. Incorrect answer choices often supply statements that both speakers would agree with or both would disagree with.
b. But just because its discussed doesn't mean it's the right answer to which the two would disagree
3. The view of one speaker is unknown:
a. Some answers supply only of the speakers' views.
b. The correct answer must contain a "point of disagreement" so these are always wrong
point at issue
The Agree/ Disagree Test:
The correct answer must produce responses where one speaker would say "I agree, the statement is correct" and the other would say "I disagree, the statement is incorrect."
Overlay many question types.
Synonyms: proposition and precept
Principle: broad rule that specifies what actions or judgments are correct in certain situations
principle "conform" questions
"conform": sometimes it asks if the stimulus conforms [=Strengthen principle Q]. Sometimes it asks if the answer choice conforms [=Must principle Q]
1. Must be true principle questions:
a. Must use the principle presented in the stimulus and then apply it to the situation in each answer choice
i. Many principles in stimuli are conditional = diagram
2. Strengthen/justify principle questions:
i. The answer choice contains a principle that acts as an additional, broad premise that supports or proves the conclusion
ii. When reading the stimulus, identify an underlying idea/belief that can be used to draw the conclusion in the stimulus
iii. Tie this idea/belief to the structure of the author's argument and ask if it supports it
How to answer principle questions:
1. If the sufficient condition [the a in "a > b"] is met in one of the scenarios of the answer choice, then it can be concluded that the necessary condition has occurred
2. If the necessary condition is not met in one of the scenarios, then it can be concluded that the sufficient condition has not occurred
3. If the sufficient condition is not met in one of the scenarios in the answer choice, you can conclude that the necessary condition may or may not have occurred
4. If the necessary condition is met in one of the scenarios in the answer choice, you can conclude that the sufficient condition may or may not have occurred
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