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GMAT CRITICAL REASONING REVIEW PART I—Types of Arguments ARGUMENT DEFINITION An argument is a connected series of statements or propositions intended to provide support, justification or evidence for the truth of another statement or proposition.
Arguments consist of one or more premises and a conclusion. Premises + Conclusion = Argument Reasons + Claim = Argument Premises are those statements that are taken to provide the support or evidence; the conclusion is that which the premises allegedly support. þ A conclusion is a statement the author wants you to believe. þ Conclusions are ideas that require evidence to support them. þ Conclusions are derived from reasoning. The conclusion will not be: • Examples • Statistics • Definitions • Background Information • Evidence Conclusion indicator words: but, proves that, consequently, shows that, hence, so, indicates that, suggests that, in fact, in short, it follows that, therefore, thus, it is highly probable that, the truth of the matter is, it should be clear that, points to the conclusion that, we may deduce that, etc.
Note: When someone claims something is true or ought to be done and provides no statements to support the claim, that claim is not a conclusion because no basis for belief has been offered; it’s an opinion instead, and can be dismissed as such. Deductive Arguments � Arguments based on laws, rules, or other widely accepted principles are best expressed deductively. � A deductive argument is termed “valid” or “sound” if the conclusion logically follows from the premises. If not, they’re considered “invalid” or “unsound.” � A deductive conclusion may be judged “true” or “false.” – If both premises are true, the conclusion is true. – If the argument contains an assumption, the writer/speaker must prove the truth of the assumption in order to establish the truth of the argument. � Deductive reasoning applies what the writer already knows. Though it does not necessarily or always yield anything new, it builds stronger arguments than does inductive reasoning because it offers the certainty of a conclusion’s being true or false.
Corpse + Interviews + Arrest + Denial (by defendant) + Threat (by prosecutor) + Plea Bargain + Hearing/Trial + Confession/Twist = Episode Theme song: https://www.youtube.com/watch?v=xz4-‐aEGvqQM
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Deductive
Diagnosis: “You’re ticklish under your jaw.” “You ate at Taco Bell.” https://www.youtube.com/watch?v=wYlVBhwfvL4
Inductive Arguments � Arguments that establish the truth of the conclusion as “probable” or “probably true.” � Induction is usually described as moving from the specific to the general. � Arguments based on experience or observation are best expressed inductively. � It begins with the evidence of specific facts, observations, or experiences and moves to a general conclusion. � Inductive conclusions are considered “reliable” or “unreliable” (not true or false) in relation to the quantity and quality of the evidence supporting it. An inductive conclusion indicates probability, the degree to which the conclusion is likely to be true.
� Frustrating though it may be for those who seek certainty, inductive thinking is, of necessity, based only on a sampling of the facts. � Induction leads to new “truths.” Induction can support statements about the unknown on the basis of what is known.
r Inductive
Examples “Given the view that species evolve into one another, then members of one species must somehow give rise to members of another species. It follows that members of the second species must somehow derive as variants of members of the first.” —Stuart A. Kauffman, The Origins of Order: Self-‐Organization and Selection in Evolution Deductive “Dumbbell training is inherently safe. I’ve never observed a torn muscle or any other serious injury resulting from the proper use of dumbbells.” —Bill Philips, Body for Life Inductive
PART II—Inferences & Assumptions Inferences � An intellectual act by which one concludes that something is true in light of something else’s being true, or seeming to be true. � It’s a conclusion about the unknown based on the known. � Inferences can be accurate or inaccurate, logical or illogical, justified or unjustified. � The inference is the movement of thought from the premises to the conclusion.
Summary of An American Tragedy: Clyde Griffiths, a son of evangelists, takes a job as a bellhop, is involved in an automobile accident, escapes to another city, finds work in his uncle’s factory, divides his affection between a factory girl and a socialite, entices the pregnant factory girl to a lake, lets her drown, and is himself tried, sentenced, and electrocuted.
Assumptions � Something we take for granted or presuppose. � Usually it is something we previously learned and do not question. � It is part of our system of beliefs. � We assume our beliefs to be true and use them to interpret our world. � If our belief is a sound one, our assumption is sound. � If our belief is not sound, our assumption is not sound. Often different people make different inferences because they bring to situations different viewpoints. They see the data differently. To put it another way, they make different assumptions about what they see. For example, two people see a man lying in a gutter. � One might infer, “There’s a drunken bum.” � The other might infer, “There’s a man in need of help.”
These inferences are based on different assumptions about the conditions under which people end up in gutters. Moreover, these assumptions are connected to each person’s viewpoint about people. � The first person assumes, “Only drunks are to be found in gutters.” � The second person assumes, “People lying in the gutter are in need of help.” � The first person may have developed the point of view that people are fundamentally responsible for what happens to them and ought to be able to care for themselves. � The second may have developed the point of view that the problems people have are often caused by forces and events beyond their control. The reasoning of these two people, in terms of their inferences and assumptions, could be characterized in the following way: Situation: A man is lying in the gutter. Inference: That man’s a bum. Assumption: Only bums lie in gutters.
Situation: A man is lying in the gutter. Inference: That man is in need of help. Assumption: Anyone lying in the gutter is in need of help.
PART III—Distinguishing Between Issues, Conclusions & Evidence
Example #1: Supreme Court Justice Potter Stewart once quipped that though he couldn't define pornography, he knew it when he saw it. “Will Internet filtering software ever have it that easy? Not anytime soon, and not without a lot of human intervention. The Internet is too vast and diverse, and the applications too indiscriminate in their quest for the obscene and the pornographic.” Issue: Will Internet filtering software ever have it that easy? Conclusion: Not anytime soon, and not without a lot of human intervention.
Reasons: The Internet is too vast and diverse, and the applications too indiscriminate in their quest for the obscene and the pornographic.
Example #2: For a better college learning environment, all classes should begin in the afternoon. Most students try to schedule afternoon or evening classes anyway; you rarely hear of a student who is upset at being closed out of the 8 a.m. section of a class. Also, experts say that students who are alert learn more and learn more quickly. For example, at Southern State University, one group of students took an 8 a.m. psychology course from Dr. Miller while another group took the same course from Dr. Miller at 2 p.m. The students in the afternoon class had slightly higher averages than those in the morning class. Changing the starting time for classes at universities to afternoon will help students.
Issue: Should starting times for classes be changed to help students learn? Conclusion: All classes should begin in the afternoon.
Example #3: Corporate managers are always interested in techniques for increasing the productivity of their workers. One interesting suggestion made by productivity consultants is to pipe music into the work area. Several recent studies have explored the extent to which different types of music affect workers output. The primary hypothesis examined in the studies was that soft-‐rock music would prove the greatest aid
to productivity. The research has found almost universally that country and western music is the greatest inducement to efficiency. Therefore, corporate officials should seriously consider playing country and western music as a stimulus to worker productivity. Issue: Should music be played to improve worker productivity? Conclusion: Play country western music to improve productivity. Reason: Studies indicate that country/western music promotes worker efficiency. Part IV—Logical Fallacies/Errors of Argument
Term Definition Example(s)
1 False Cause/Causation Fallacy
Arguing that because Event B occurred after Event A, Event A caused Event B
⦁ “There was an increase of births during the full moon. Therefore, full moons cause birth rates to rise.” ⦁ “I drank a ‘Coldbuster’ Jamba Juice and three days later my cold disappeared!”
2 Generalization/ Stereotyping
Conclusion is unjustified due to insufficient/biased evidence
⦁ “Professor Brugger is a hard grader because he gave my roommate a D-‐ last year.” ⦁ “The majority of people in the United States die in hospitals, so stay out of them.” ⦁ “I got bitten by a bunny once. I think they should all be slaughtered. What biological purpose do they serve?”
3 False Analogy/Faulty
Comparison Basing an argument on a poor comparison of two things, ideas, events or situations; comparing “apples and oranges”
⦁ “Teaching kids about sex education is like letting them loose in a candy store.” ⦁ “The American Indian had to make way for Western civilization; after all, you can't make an omelet without breaking a few eggs.” ⦁ “Since the mind is essentially a wet computer, our task is to figure out how we can best program it!”
4 Appeal to False Authority/Association Fallacy
Ideas or actions are (un)acceptable because of people associated with them
⦁ “The hijackers were Egyptian; obviously Egyptians support terrorism.”
5
Ad Hominem (“to the man”)/Personal Attack
An attack on the character of the individual rather than his/her actual arguments or qualifications
⦁ “Rudy Giuliani divorced his loving wife of many years. How could he possibly be qualified to be mayor?”
6 False Dilemma/Either-‐
Or Fallacy An oversimplification that reduces alternatives to only two choices when more may actually exist
⦁ “Either we ban boxing or hundreds of young men will be senselessly killed.” ⦁ “Patients either get better or they don’t.” ⦁ “America: Love it or leave it.”
7 Begging the Question Loading the conclusion in the claim;
assuming that something is true before it’s proven
⦁ “The antiwar demonstrators of the 1970s should be remembered as the cowards that they were.”
https://www.youtube.com/watch?v=3m5qxZm_JqM
8 Ambiguity/Equivocation Two types: the word or phrase may be ambiguous, in which case it has more than one distinct meaning OR the word or phrase may be vague, in which case it has no distinct meaning
⦁ “President Clinton should’ve been impeached only if he had improper relations with Monica Lewinsky. He didn’t have relations with Lewinsky. Therefore, he shouldn’t have been impeached.”
Boneless Chicken
9 Shifting Burden of Proof/Appeal to Ignorance
Whatever has not been proven false must necessarily be true; whatever has not been proven true must necessarily be false. Absence of evidence is evidence.
⦁ “There is no compelling evidence that UFOs are not visiting the Earth; therefore, UFOs exist.” ⦁ “In its 30+ years, SETI hasn’t ever detected signals from an ET, so neither aliens nor their UFOs exist.”
10 Contradiction Simultaneous acceptance and denial of a
proposition or statement; two contradictory inferences can be drawn from the premise
⦁ “Intelligent people have open minds. Politicians are supposed to be intelligent. But anyone who says that recreational drugs shouldn’t be legalized has a closed mind. Therefore, politicians are not intelligent people.”
11 Fallacy of Composition A property shared by a number of
individual items, is also shared by a collection of those items; a property of the parts of an object, must also be a property of the whole
⦁ “This new truck is made entirely of lightweight aluminum components, and is therefore very lightweight.”
12 Fallacy of Division Assuming that a property of some thing
must apply to its parts; a property of a collection of items is shared by each item.
⦁ “Ocelots are now dying out. Sparky is an ocelot. Therefore, Sparky is now dying out.” ⦁ “Humans are conscious and are made of cells; therefore, each cell has consciousness.”