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Constructing Arguments Critical Thinking Ch. 10. Argument A form of thinking in which certain statements (reasons) are offered to support another statement.

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Presentation on theme: "Constructing Arguments Critical Thinking Ch. 10. Argument A form of thinking in which certain statements (reasons) are offered to support another statement."— Presentation transcript:

1 Constructing Arguments Critical Thinking Ch. 10

2 Argument A form of thinking in which certain statements (reasons) are offered to support another statement (conclusion) Chapter 10 – Recognizing arguments – Constructing arguments – Evaluating arguments – Understanding arguments – Constructing extended arguments

3 Reasoning Type of thinking that uses argument (reasons in support of conclusions) Attempt to explain, justify, and predict things

4 Cue Words for Arguments To identify reasons and conclusions Key words Signal a reason in support of a conclusion or conclusion based on certain reasons In the first place In the second place It follows that….

5 Cue Words signaling reasons Since For Because As shown by As indicated by Given that Assuming that In view of First, second.. In the first (second) place May be inferred from May be deduced from For the reason that

6 Cue Words Signaling Conclusions Then It follow that Thereby showing Demonstrates that Allows us to infer that Leads me to believe that Allows us to deduce that Consequently Therefore Thus Hence So (which) shows that (which) proves that Implies that Points to As a result

7 http://www.nytimes.com/books/98/03/01/ home/vidal-drugs.html Drugs: Case for Legalizing Marijuana By GORE VIDAL In the Long Run It Would Save Lives And End Hypocrisy It is possible to stop most drug addiction in the United States within a very short time. Simply make all drugs available and sell them at cost. Label each drug with a precise description of what effect--good and bad--the drug will have on whoever takes it. This will require heroic honesty. Don't say that marijuana is addictive or dangerous when it is neither, as millions of people know--unlike "speed," which kills most unpleasantly, or heroin, which is addictive and difficult to kick. For the record, I have tried--once--almost every drug and liked none, disproving the popular Fu Manchu theory that a single whiff of opium will enslave the mind. Nevertheless many drugs are bad for certain people to take and they should be told about them in a sensible way. Along with exhortation and warning, it might be good for our citizens to recall (or learn for the first time) that the United States was the creation of men who believed that each man has the right to do what he wants with his own life as long as he does not interfere with his neighbor's pursuit of happiness (that his neighbor's idea of happiness is persecuting others does confuse matters a bit).

8 http://www.nytimes.com/books/98/0 3/01/home/vidal-drugs.html This is a startling notion to the current generation of Americans who reflect on our system of public education which has made the Bill of Rights, literally, unacceptable to a majority of high school graduates (see the annual Purdue reports) who now form the "silent majority"--a phrase which that underestimated wit Richard Nixon took from Homer who used it to describe the dead. Now one can hear the warning rumble begin: if everyone is allowed to take drugs everyone will and the GNP will decrease, the Commies will stop us from making everyone free, and we shall end up a race of Zombies, passively murmuring "groovie" to one another. Alarming thought. Yet it seems most unlikely that any reasonably sane person will become a drug addict if he knows in advance what addiction is going to be like. Is everyone reasonably sane? No. Some people will always become drug addicts just as some people will always become alcoholics, and it is just too bad. Every man, however, has the power (and should have the right) to kill himself if he chooses. But since most men don't, they won't be mainliners either. Nevertheless, forbidding people things they like or think they might enjoy only makes them want those things all the more. This psychological insight is, for some mysterious reason, perennially denied our governors. It is a lucky thing for the American moralist that our country has always existed in a kind of time- vacuum: we have no public memory of anything that happened before last Tuesday. No one in Washington today recalls what happened during the years alcohol was forbidden to the people by a Congress that thought it had a divine mission to stamp out Demon Rum and so launched the greatest crime wave in the country's history, caused thousands of deaths from bad alcohol, and created a general (and persisting) contempt for the laws of the United States.

9 The same thing is happening today. But the government has learned nothing from past attempts at prohibition, not to mention repression. Last year when the supply of Mexican marijuana was slightly curtailed by the Feds, the pushers got the kids hooked on heroin and deaths increased dramatically, particularly in New York. Whose fault? Evil men like the Mafiosi? Permissive Dr. Spock? Wild-eyed Dr. Leary? No. The Government of the United States was responsible for those deaths. The bureaucratic machine has a vested interest in playing cops and robbers. Both the Bureau of Narcotics and the Mafia want strong laws against the sale and use of drugs because if drugs are sold at cost there would be no money in it for anyone. If there was no money in it for the Mafia, there would be no friendly playground pushers, and addicts would not commit crimes to pay for the next fix. Finally, if there was no money in it, the Bureau of Narcotics would wither away, something they're not about to do without a struggle. Will anything sensible be done? Of course not. The American people are as devoted to the idea of sin and its punishment as they are to making money--and fighting drugs is nearly as big a business as pushing them. Since the combination of sin and money is irresistible (particularly to the professional politician), the situation will only grow worse. Gore Vidal, playwright and novelist, is the author of the newly published "Two Sisters."

10 The Case for Slavery by A.M. Rosenthal http://query.nytimes.com/gst/fullpage.html?res=950DE4DC173C F935A1575AC0A96F948260 http://query.nytimes.com/gst/fullpage.html?res=950DE4DC173C F935A1575AC0A96F948260 September 26, 1989ON MY MIND; The Case For Slavery By A. M. RosenthalLEAD: Across the country, a scattered but influential collection of intellectuals is intensely engaged in making the case for slavery. With considerable passion, these Americans are repeatedly expounding the benefits of not only tolerating slavery but legalizing it: It would make life less dangerous for the free. It would save a great deal of money. And since the economies could be used to improve the lot of the slaves, in the end they would be better off. The new anti-abolitionists, like their predecessors in the 19th century, concede that those now in bondage do not themselves see the benefits of legalizing their status. But in time they will, we are assured, because the beautiful part of legalization is that slavery would be designed so as to keep slaves pacified with the very thing that enslaves them! The form of slavery under discussion is drug addiction. It does not have every characteristic of more traditional forms of bondage. But they have enough in common to make the comparison morally valid - and the campaign for drug legalization morally disgusting.

11 The Case for Slavery (cont’d) Like the plantation slavery that was a foundation of American society for so long, drug addiction largely involves specifiable groups of people. Most of the enchained are children and adolescents of all colors and black and Hispanic adults. Like plantation slavery, drug addiction is passed on from generation to generation. And this may be the most important similarity: like plantation slavery, addiction can de-stroy among its victims the social resources most valuable to free people for their own betterment - family life, family traditions, family values. In plantation-time America, mothers were taken from their children. In drug-time America, mothers abandon their children. Do the children suffer less, or the mothers? Anti-abolitionists argue that legalization would make drugs so cheap and available that the profit for crime would be removed. Well-supplied addicts would be peaceful addicts. We would not waste billions for jails and could spend some of the savings helping the addicted become drug-free. That would happen at the very time that new millions of Americans were being enticed into addiction by legalization - somehow. dangerous social disorder.

12 The Case for Slavery (cont’d) Are we really foolish enough to believe that tens of thousands of drug gang members would meekly steal away, foiled by the marvels of the free market? Not likely. The pushers would cut prices, making more money than ever from the ever-growing mass market. They would immediately increase the potency and variety beyond anything available at any Government-approved narcotics counters. Crime would increase. Crack produces paranoid violence. More permissiveness equals more use equals more violence. And what will legalization do to the brains of Americans drawn into drug slavery by easy availability? Earlier this year, an expert drug pediatrician told me that after only a few months babies born with crack addiction seemed to recover. Now we learn that stultifying behavioral effects last at least through early childhood. Will they last forever? How long will crack affect neurological patterns in the brains of adult crack users? Dr. Gabriel G. Nahas of Columbia University argues in his new book, ''Cocaine: The Great White Plague,'' that the damage may be irreversible. Would it not be an act of simple intelligence to drop the legalization campaign until we find out?

13 Then why do a number of writers and academicians, left to right, support it? I have discussed this with anti-drug leaders like Jesse Jackson, Dr. Mitchell Rosenthal of Phoenix House and William J. Bennett, who search for answers themselves. Perhaps the answer is that the legalizers are not dealing with reality in America. I think the reason has to do with class. Crack is beginning to move into the white middle and upper classes. That is a tragedy for those addicted. However, it has not yet destroyed the communities around which their lives revolve, not taken over every street and doorway. It has not passed generation to generation among them, killing the continuity of family. But in ghetto communities poverty and drugs come together in a catalytic reaction that is reducing them to social rubble. The anti-abolitionists, virtually all white and well-to-do, do not see or do not care. Either way they show symptoms of the callousness of class. That can be a particularly dangerous social disorder. The Case for Slavery (cont’d)

14 Arguments as Inferences Inferring: a thinking process Reasoning from what you already know (or believe to be true) to form new knowledge or beliefs Work from reasons we know or believe it to form conclusions based on these reasons

15 Arguments Decide Explain Predict Persuade

16 Argument to Decide Reason: Throughout my life, I’ve always been interested in all different kinds of electricity. Reason: There are many attractive job opportunities in the field of electrical engineering. Conclusion: I will work toward becoming an electrical engineer.

17 Argument to Explain Reason: I was delayed in leaving my house because my dog needed an emergency walking. Reason: There was an unexpected traffic jam caused by motorists slowing down to view an overturned chicken truck. Conclusion: Therefore, I was late for our appointment.

18 Argument to Predict Reason: Some people will always drive faster than the speed limit allows, whether the limit is 55 or 65 mph. Reason: Car accidents are more likely to occur at higher speeds. Conclusion: It follows that the newly reinstated 65-mph speed limit will result in more accidents.

19 Arguments to Persuade Reason: Chewing tobacco can lead to cancer of the mouth and throat. Reason: Boys sometimes are led to begin chewing tobacco by ads for the product that feature sports heroes they admire. Conclusion: Therefore, ads for chewing tobacco should be banned.

20 Evaluating Arguments Investigate 2 aspects of arguments independently – How true are the reasons being offered to support the conclusion? – To what extent do the reasons support the conclusion or to what extent does the conclusion follow from the reasons offered?

21 How true are the supporting reasons? Analyze the reasons to determine how true they are: – Does each reason make sense? – What evidence is being offered as part of each reason? – Do you know each reason to be true based on your experience? – Is each reasons based on a source that can be trusted?

22 Do the reasons support the conclusion? Investigate the relationship between the reasons and the conclusion. Is the argument valid or invalid? Do the reasons support the conclusion? Does the conclusion follow from the reasons being offered?

23 Soundness of Arguments True reasons + valid structure = sound argument False reasons and/or invalid structure = unsound argument Truth and validity are not the same concepts Evaluating arguments effectively involves both the truth of the reasons and the validity of the argument’s structure.

24 Deductive Arguments Associated with study of logic If you accept the supporting reasons (premises) as true, then you must necessarily accept the conclusions as true. An argument form in which one reasons from premises that are known or assumed to be true to a conclusion that follows necessarily from those premises.

25 Syllogism Argument form that consists of 2 supporting premises and a conclusion Reason/Premise: All men are mortal. Reason/Premise: Socrates is a man. Conclusion: Therefore, Socrates is mortal. Not all syllogisms are valid. Invalid deductive forms: – All men are mortal. – Socrates is a man. – Therefore, all men are Socrates.

26 Socrates Syllogism: Application of a General Rule: All A is B. Premise: All A (men) are B (mortal) Premise: S is an A (Socrates is a man) Conclusion: Therefore, S is B (Socrates is a man).

27 Effective discussion Listening carefully to other points of view Supporting views with reasons and evidence Responding to the points being made Asking – and trying to answer – appropriate questions Working to increase understanding, not simply to “win the argument”

28 Constructing Extended Arguments Define a thesis Conduct research Organize ideas.

29 Modus Ponens Affirming the antecedent Premise: If I have prepared thoroughly for the final exam, then I will do well. Premise: I prepared thoroughly for the exam. Conclusion: Therefore, I will do well on the exam. Argument Structure If A, then B. Premise: A Conclusion: Therefore B.

30 Modus Tollens Denying the consequences Premise: If Michael were a really good friend, he would lend me his car for the weekend. Premise: Michael refuses to lend me his car for the weekend. Conclusion: Therefore, Michael is not a really good friend. Argument structure Premise: If A, then B. Premise: Not B. Conclusion: Therefore, not A.

31 Disjunctive syllogism Presenting several alternatives Premise: Either I left my wallet on my dresser, or I have lost it. Premise: The wallet is not on my dresser. Conclusion, Therefore, I must have lost it. Argument structure Premise: Either A or B. Premise: Not A. Conclusion: Therefore, B.


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