8. Questions On Deduction
from 8. Deduction in Clear Thinking by R W Jepson

1. On the assumption that a man must be over 21 years of age to qualify for a vote, does it necessarily follow that:
   1. If Smith has a vote, he is over 21.
   2. Every man who is over 21 has a vote.
   3. A man who is under 21 has no vote.
   4. If a man has no vote, he is under 21.
   5. Either Smith has a vote, or he is under 21.
   6. Either a man has no vote, or he is over 21.
2. During war time the Government put many restrictions on individual liberty and you tolerated them willingly. Are you entitled to infer from this fact that you are justified in being loth to tolerate restrictions in peace time? Give a reason for your answer.
3. What conclusion can be validly drawn from the following pairs of statements? Where no conclusion can be validly drawn, state the reason.
   1. All actuaries are mathematicians:— All statisticians are mathematicians.
   2. Some criminals are deserters:— Smith is a deserter.
   3. No professionals are allowed to compete:— Smith is an amateur.
   4. No professionals are allowed to compete — Smith is not allowed to compete.
   5. No professionals are allowed to compete:— Smith is allowed to compete.
   6. In all bureaucracies corruption is rife — Corruption is rife in Ruritania.
4. On what generalisations are the following opinions based?
   1. The customer cannot expect much consideration from a monopoly like the London Passenger Transport Board.
   2. Doctrinaire? Why, of course : he comes from the X— School of Economics.
   3. You need have no hesitation about buying this house. The drains are in perfect order.
   4. Why do you blush? You have nothing to be ashamed of.
   5. You say the novel you refer to is all about Wessex? Ten to one it was written by Thomas Hardy.

The following arguments are set for analysis and criticism on the lines of the examples in the text of this chapter

5. Look at all those people walking! They must have missed the bus.
6. Nations with large armies carry great weight in international affairs. If therefore a nation wishes to be influential, it must maintain a large army.
7. Si vis pacem, para bellum. Ruritania is preparing for war, therefore she wishes for peace.
8. Luck too often favours the undeserving examination candidate. If luck could be eliminated from examinations, the deserving candidate would have a better chance of success.
9. All the best poets are word-artists. If therefore you cultivate artistry in the use of words, you will write good poetry.
10. Youth is not the period for contented acquiescence. Only those who have forgone their ambitions are contented; and no young person lacks ambition.
11. It is pretty obvious this burglary is the work of a real professional: no amateur would have been half so clever.
12. All the unruly elements in the school come from the X district—what else could you expect?
13. Mother (to son) : You'd better ask your form-master.
    Father: Every human being is liable to error and schoolmasters are no exception; so your form-master is not infallible.
14. A.: There's been a great increase in crime lately, especially in burglary. I expect it's due to all these deserters from the army who are afraid to disclose their identity and therefore can only earn a livelihood by dishonest means.
    B.: No doubt desertion may lead to crime. But to attribute all the increase in crime to deserters is to stigmatise unduly a great many men who, however mistaken they may be in not facing the consequences of desertion, have not stooped so low as to break the criminal law.
15. Irishman (looking at the result of the draw of a sweep ) : What a hit of luck!
    B. : Why, have you drawn a horse?
    I. : No.
    B.: Then why are you lucky?
    I.: Because I didn't buy a ticket.
16. The Prime Minister's broadcast the other night on the fuel crisis was a ' flop '—he was so cold and matter of fact. People won't rise to the occasion in a crisis unless their feelings are roused and their imagination stirred.
17. You can't make a man moral by Act of Parliament, so the new Betting Bill is doomed to failure at the outset.
18. Workers will not give of their best unless they are contented. There is widespread discontent among the industrial workers in the X district caused by the lack of suitable housing accommodation, and so the output per man-hour in the X factories is low compared with that in the neighbouring town of Y where the housing problem is less acute.
19. He must be a sailor. Look at his rolling gait.
20. If a boy cheats in an examination, he deserves to fail. But Smith did not cheat, therefore he did not deserve to fail.
21. I always keep strictly to the law. But I have looked carefully and cannot find any regulation that forbids me to do this, therefore I am justified in doing it.
22. No Church of England clergyman is allowed to sit in the House of Commons. It follows that all M.P.s are laymen.
23. He is the finest character I know. I do not believe he has a single vice.
24. If anyone wishes to get on in politics these days, he must either be uncommonly clever or possess unlimited means. Smith has plenty of money and brains and so is sure to succeed.
25. Genius is akin to madness. As Smith is no genius, he is never likely to lose his reason.
26. Whatever is rare and desired is dear. Cheap diamonds are rare and desired : therefore cheap diamonds are dear.
27. At the election one ought to vote for clever candidates, but so many candidates are stupid that it is better not to vote at all.
28. No law-abiding man steals. I don't steal : therefore I am a law-abiding man.
29. Appearances are deceitful. Smith looks honest, and so the odds are he's a scoundrel.
30. Killing a man is murder, so capital punishment is murder, for it involves killing a man.
31. Counsel For The Prosecution: My learned friend has made an irrelevant observation. Other distinguished lawyers have done the same, so he is in good company.
    Counsel For The Defence: I hasten to assure my learned friend that the observation I made was very far from being irrelevant, as I hope to show later.
    Judge: It follows therefore that you cannot be a distinguished lawyer. (Laughter in Court.)
32. Colonies are indispensable if we are to he prosperous. For if we had no colonies, from where could we be sure of obtaining the raw materials for the industries on which we depend for our prosperity?
33. No child can really learn unless his curiosity has been awakened and unless the interest aroused by this curiosity is strong enough to induce him to satisfy it. No teacher can expect to awaken curiosity or stimulate interest in a child unless his methods are such as to induce a state of willing receptivity which can only exist in a happy and contented mind. Harsh methods and Spartan discipline may succeed in driving knowledge into unwilling heads but the knowledge thus acquired is seldom of any lasting advantage and if it is retained at all, the interest behind its retention is the result of fear, not of willing co-operation. Hence it is the prime business of every teacher to make his pupils happy and contented : they will thus regard learning as a form of self-amusement; and indeed the only effective way to learn is by amusing oneself.
34. Russian propaganda is very busy at the moment telling the world that Great Britain should reduce her military forces drastically and withdraw her armies from Greece. the Middle East and other quarters, as well as from the occupied zone of Germany. Many Labour back-benchers, as well as the Communist Party, are urging the same. The Russian influence, thus obvious in and out of the House of Commons, is a very disturbing feature in contemporary politics.
35. A general ought to be the servant of his own government, and of no other. It follows that whatever rewards he receives for his services ought to be given either by his own government, or with the full knowledge and approbation of his own government. This rule ought to be strictly maintained even with respect to the merest bauble, with respect to a cross, a medal, or a yard of coloured riband. But how can any government be well served, if those who command its forces are at liberty, without its permission, without its privity, to accept princely fortunes from its allies?

    It is idle to say that there was then no Act of Parliament prohibiting the practice of taking presents from Asiatic sovereigns. It is not on the Act which was passed at a later period for the purpose of preventing any such taking of presents, but on grounds which were valid before that Act was passed, on grounds of common law and common sense, that we arraign the conduct of Clive. There is no act that we know of, prohibiting the Secretary of State for Foreign Affairs from being in the pay of continental powers. But it is not the less true that a Secretary who should receive a secret pension from France would grossly violate his duty, and would deserve severe punishment.(— MACAULAY, Clive.)

36. An Incident At The Mad Hatter's Tea-Party
    "I believe I can guess that," Alice added aloud.
    "Do you mean that you think you can find out the answer to it? " said the March Hare.
    " Exactly so," said Alice.
    "Then you should say what you mean," the March Hare went on.
    "I do," Alice hastily replied; "at least—at least I mean what I say—that's the same thing, you know."
    "Not the same thing a bit! " said the Hatter. "You might just as well say that ' I see what I eat ' is the same thing as 'I eat what I see'!"
    You might just as well say," added the March Hare, "that ' I like what I get' is the same thing as ' I get what I like '
37. Alice In Wonderland Again
    Alice, in one of her very tall moments, finds herself looking down into a nest of pigeon's eggs in the topmost branches of a tree. "Serpent!" screamed the Pigeon.
    "You're a serpent; and there's no use denying it. I suppose you'll be telling me that you've never tasted an egg!"
    "Little girls eat eggs quite as much as serpents do, you know."
    "I don't believe it," said the Pigeon; "but if they do, why, then, they're a kind of serpent, that's all I can say."
38. The second Caliph, Omar, after his capture of Alexandria in 642, justified the burning of the famous library there by saying that its destruction would be no loss, for if the volumes contained the same doctrines as the Koran, they were unnecessary, and if they contained doctrines at variance with those of the Koran, they were pernicious.
39. It is useless forcing the employers to raise the wages of their employees : for either they will close their works and thus throw the employees out of work; or they will pass on the increased cost to the consumer, the consumer will then buy fewer manufactured products, and the employees who remain at work will be put on short time and will earn no more and perhaps less than they did before.
40. It is no good compelling undergraduates to attend their College Chapel. If they care about it, they will attend in any case; if they do not, then it cannot do them any kind of good.
41. No conscientious barrister would defend an accused person. For an accused person is either innocent or guilty. If he is innocent the fact must be evident to the judge. If he is guilty, then he ought not to be defended.
42. A young man aspiring to be a barrister promised to pay his tutor for his lessons as soon as he had won a case. A brief did not come his way until he was sued by his tutor for payment. He then argued that if he won his case, according to the judge's decision, he would not have to pay; and that if he lost, the terms of his agreement would not have been fulfilled, and he would still not have to pay. "Not at all," replied his tutor, "if you win, you must pay according to the terms of our agreement; and if you lose, the judge will condemn you to pay."