Reference no: EM13762895

Part 1-

I. What is wrong with the following statements?

1. Validity is when an argument is true; i.e., its premises are true and its conclusion is true.

2. An argument is valid when it is both sound and true.

3. Premises can be true or false; conclusions are sound or unsound.

4. An argument's validity depends on the truth of its premises.

5. An argument's soundness depends upon its form.

II. Determine whether the following statements are true or false, and why.

1. A valid argument can have false premises.

2. A sound argument can have a false conclusion.

3. If an argument is sound, then it must be valid.

4. All valid arguments are also sound arguments.

5. All sound arguments are also valid arguments.

6. If an argument has all true premises and a true conclusion, then it is sound.

7. A valid argument must have a true conclusion.

8. It is correct to say that an argument is true or false.

9. An invalid argument must have at least one false premise.

10. An invalid argument must have a false conclusion.

Part 2-

I. Find the valid forms:

1. If a then b

b

a

2. Not b

If a then b

Not a

3. a or b

If a then c

If b then d

If a then d

4. If a then b

If c then d

a or c

b or d

5. Not b

If b then a

Not a

6. If a then b

If c then d

If a then d

II. Symbolize the following arguments, putting them into standard form and determine whether they possess one of our five valid forms or our two formal fallacies. Watch for reversals of the "if-then" statement (e.g. a statement like "I will go if you go" needs to move the "if" part up front: "If you go then I will go" -- "If y then i"; not "i if y.")

1. Either my roommate is in the gym or she is in the cafeteria. But since you have found that she is not in the cafeteria, then she must be in the gym.

2. If everything we do is determined by forces in our environment then we never exercise free will. Thus, we never do exercise free will, because it has been proven that everything we do is determined by forces in our environment.

3. Entering this building is permitted if you have an identification tag. You are not permitted to enter this building, though, because you do not have an identification tag.

4. Either the soil is too acidic for these plants or there is not enough sunlight for them. If the soil is too acidic, then we will have to move the plants. We will also have to move the plants if there is not enough sunlight. So, it seems that we will definitely have to move the plants.

5. It says in the text that if sulfuric acid is too strong, then it will corrode the steel pipes. It will definitely not corrode our steel pipes, because I have determined that the acid is not too strong.

6. Gadgets flimp in cadence. But gadgets flimp in cadence if widgets will slurp obtrusively. Consequently, widgets will slurp obtrusively.

7. This drug is either a cure for cancer or it is a deadly poison. Consequently, it should be mass-produced or it should be destroyed. My reasoning for this is that it should be destroyed if it is a deadly poison, and that if it is a cure for cancer, then it should be mass-produced.

8. This rain is not caused by volcanic ash in the atmosphere. Thus this rain is caused by smog, because scientists have determined that this rain is caused either by volcanic ash in the atmosphere or by smog.

9. If the mind is the same as the brain, then the mind is material. It follows, then, that the mind is the same as the brain if the mind decomposes at death. This is because the mind will decompose at death if it is material.

10. If Senator Sly supports our state, then he will have voted for the new tax bill. I know this to be true because if he goes to Washington, he will have voted for the new tax bill, and because he goes to Washington if he supports our state.

11. Either I will take chemistry or I will take French next term. If I take French I should buy a French dictionary; I should buy a calculator if I take chemistry. Therefore, I should buy a French dictionary and I should buy a calculator.

12. If that star were a nova, then we would certainly see it. This is because we would see it if it radiates much more light, and because if it is a nova it will radiate much more light.

Part 3-

Name the fallacy in the following examples.

1. Given the performance of the three students I've had in class from Ridgemont High School, I'd have to say the people from there are losers.

2. Mom, everybody's wearing green tennis shoes at school now; I won't be popular unless I've got some.

3. Did you fail the exam because you're lazy, or because you're stupid?

4. The layoffs at Boeing were clearly racist: over 60% of the people laid off were black or Puerto Rican.

5. Arthur denies that he is a conservative, so he must be a liberal.

6. Are we to support federal welfare programs, or are we to let people starve on the streets?

7. There can be no truth in Nietzsche's philosophy, for Nietzsche was a man who deserted his friends and betrayed those who trusted him.

8. The Sonics are the outstanding team in the conference, because they have the best players and the best coach. We know they have the best players and the best coach because they will win the conference title. And they will win the conference title because they deserve to win the conference title. Of course they deserve to win the conference title, for they are the outstanding team in the conference.

9. Welfare is a scam. I know a guy who runs a secret gambling operation and drives a Cadillac down to collect his welfare check.

10. A car has either got to be good quality or cheap. I don't want a cheap piece of junk, and I can't afford a good one. That's why I don't have a car.

11. The sun illuminates the earth as a torch illuminates an object. But one moves a torch to illuminate one's house, rather than moving the house to be illuminated by the torch. Hence it is the sun which revolves around the earth rather than the earth around the sun.

12. Newspaper headline: After two nights of looting and rioting, the mayor called a curfew for the next night.

13. The chiropractors have failed entirely in their attempts to establish a scientific basis for their concepts. This question can therefore be settled once and for all. Chiropractic has no basis in science.

14. It is our duty to do what is right. We have the right to disregard good advice. Hence, it is our duty to disregard good advice.

15. When questioned about someone in the State Department whom he had claimed had Communist affiliations, the late Sen. Joe McCarthy declared: "I do not have much information on this except the general statement of the agency that there is nothing in the files to disprove his Communist connection."

16. Scott insists that the Bell curve is not an accurate measure of group performance. He has been an accounting major for three years now, so he knows a lot about mathematics.

Part 4-

Additional Exercises

I. Indicate which of the following passages present arguments. Write out the conclusion of each argument.

1. "I came, I saw, I conquered." -- Julius Caesar, attributed by Suetonius, The Lives of the Caears.

2. "All happy families resemble one another, but each unhappy family is unhappy in its own way." -- Leo Tolstoy, Anna Karenina.

3. "When a man is tired of London, he is tired of life; for there is in London all that life can afford." -- Samuel Johnson, quoted by James Boswell, The Life of Samuel Johnson.

4. "You can fool all of the people some of the time, and some of the people all the time, but you cannot fool all the people all of the time." -- Abraham Lincoln, Speech on September 8, 1855.

5. "Your honor says, I am either a knave or a madman; now, as I'll assure your honor I am no knave, it follows that I must be mad." -- Tobias Smollet, Humphrey Clinker.

6. "If we live, we live to the Lord, and if we die, we die to the Lord; so then, whether we live or whether we die, we are the Lord's." -- Romans 14:8.

7. "He who begins by loving Christianity better than Truth will proceed by loving his own sect or church better than Christianity, and end by loving himself better than all." -- Samuel Taylor Coleridge, Aids to Reflection: Moral and Religious Aphorisms.

8. "We do not hate those who injure us, if they do not at the same time wound our self-love. We can forgive anyone sooner than those who lower us in our own opinion. It is no wonder, therefore, that we as often dislike others for their virtue as for their vices. We naturally hate whatever makes us despise ourselves." -- William Hazlitt, Characteristics.

9. "I draw the line in the dust and toss the gauntlet before the feet of tyranny, and I say segregation now, segregation tomorrow, segregation forever." -- Alabama Governor George C. Wallace, January 1963.

10. "Man, being the servant and interpreter of Nature, can do and understand so much and so much only as he has observed in fact or in thought of the course of Nature; beyond this he neither knows anything nor can do anything." -- Francis Bacon, Works.

II. Which of the following passages contain arguments, and which do not? Identify the stated premises and conclusion in each passage containing an argument.

1. "It is sufficiently agreed that all things change, and that nothing really disappears, but that the sum of matter remains exactly the same." -- Francis Bacon, Cogitationes de Natura Rerum.

2. "Ignorance of the law excuses no man; not that all men know the law, but because ‘tis an excuse every man will plead, and no man can tell how to confute him." -- John Selden, Law.

3. "All censorship exist to prevent anyone from challenging current conceptions and existing institutions. All progress is initiated by challenging current conceptions, and executed by supplanting existing institutions. Consequently the first condition of progress is the removal of censorship. There is the whole case against censorship in a nutshell." -- George Bernard Shaw, preface to Mrs. Warren's Profession.

4. "The true distinction between these forms...is, that in a democracy, the people meet and exercise the government in person; in a republic, they assemble and administer it by their representatives and agents. A democracy, consequently must be confined to a small spot. A republic may be extended over a large region." -- James Madison, The Federalist, no. 14.

5. "Science is nothing but trained and organized common sense, differing from the latter only as a veteran may differ from a raw recruit: and its methods differ from those of common sense only so far as the guardsman's cut and thrust differ from the manner in which a savage wields a club." -- T. H. Huxley, Collected Essays.

6. "All free men, wherever they may live, are citizens of Berlin. And therefore, as a free man, I take pride in the words Ich bin ein Berliner" -- John Fitzgerald Kennedy, Speech at City Hall, West Berlin, June 26, 1963.

7. "It seems that the will of God is changeable. For the Lord says (Gen. vi. 7): It repenteth Me that I have made man. But whoever repents of what he has done has a changeable will. Therefore God has a changeable will." -- Thomas Aquinas, Summa Theologica.

8. "Because intense heat is nothing else but a particular kind of painful sensation; and pain cannot exist but in a perceiving being; it follows that no intense heat can really exist in an unperceiving corporeal substance." -- George Berkeley, Three Dialogues.

9. "For only to the extent that man has fulfilled the concrete meaning of his personal existence will he also have fulfilled himself...The meaning which a being has to fulfill is something beyond himself, it is never just himself." -- Viktor E. Frankel, quoted by Milton Mayeroff in On Caring.

10. "Where force is necessary, one should make use of it boldly, resolutely, and right to the end. But it is well to know the limitations of force; to know where to blend force with manoeuvre, assault with conciliation." -- Leon Trotsky, Was nun?

III. Determine whether each of the following arguments should be regarded as deductive or inductive. (If it is not clear whether the argument was intended to be deductive or inductive, or if there appears to be disagreement between the arguer's perspective and your perspective as evaluator, then decide whether it is more reasonable to interpret the argument as deductive or inductive.)

1. Since Christians are theists and Arabella is a Christian, she is definitely a theist.

2. Since footsteps were heard outside the house, it is unlikely that a resident was the culprit.

3. All poisonous snakes native to the United States have brown and white markings, so that snake you saw in the Poconos, if it was solid black as you say, was not poisonous.

4. The lights were all out and the car was gone, so we concluded that nobody was home.

5. Most major-league baseball players who play the outfield consistently have batting averages over .250. Since Ken Singleton played centerfield for the Orioles for three consecutive years, he must have been batting over.250 when he was traded.