Chapter XXX

1. Point out any ambiguities which underlie the following propositions--

(1) Every one who has read the book in French will recommend those who have not to read it in English.

(2) I will not do this because he did it.

(3) These are all my books.

(4) By an old statute of the date of Edward III it was accorded 'that Parliament should be holden every year once or more often if need be.'

(5) They found Mary and Joseph and the babe lying in a manger.

(6) The king and his minister are feeble and unscrupulous.

(7) Heres meus uxori meae triginta pondo vasorum argenteorum dato, quae volet.

2. Examine the following arguments, formulating them when sound, and referring them, when unsound, to the proper head of fallacy--

(1) We know that thou art a teacher come from God; for no man can do these signs that thou doest, except God be with him. S. John iii. 2.

(2) 'Sir Walter Scott's novels have ceased to be popular.' 'Well, that's only because nobody reads them.'

(3) What we produce is property. The sheriff produces a prisoner. .'. A prisoner is property.

(4) As all metals are not necessarily solid, we may expect some metals to be liquid.

(5) Moses was the son of Pharaoh's daughter. .'. Moses was the daughter of Pharaoh's son.

(6) If Aeschines took part in the public rejoicings over the success of my policy, he is inconsistent in condemning it now; if he did not, he was a traitor then.

(7) It is wrong to stick knives into people. .'. Surgeons ought to be punished.

(8) If a thing admits of being taught, there must be both teachers and learners of it. .'. If there are neither teachers nor learners of a thing, that thing does not admit of being taught.

(9) It is unnecessary to lend books, if they are common, and wrong to lend them, if they are rare. Therefore books should not be lent from public libraries.

(10) Seeing is believing. .'. What is not seen cannot be believed.

(11) St. Paul was not of Jewish blood, for he was a Roman citizen.

(12) To call you an animal is to speak the truth. To call you an ass is to call you an animal. .'. To call you an ass is to speak the truth.

(13) Pain chastens folly. A life of ease must therefore be one of folly incurable.

(14) We cannot be happy in this world; for we must either indulge our passions or combat them.

(15) It must be clear to the most unlettered mind that, as all things were originally created by the Deity, including the hair on our heads and the beards on our faces, there can be no such thing as property.

(16) The crime was committed by the criminal. The criminal was committed by the magistrate. .'. The crime was committed by the magistrate.

(17) General councils are as likely to err as the fallible men of whom they consist.

(18) Dead dogs are heavier than living ones, because vitality is buoyant.

(19) Deliberation is concerned with actions. Actions are means. .'. Deliberation is concerned with means.

(20) 'No beast so fierce but has a touch of pity; But I have none: therefore I am no beast.'

(21) Practical pursuits are better than theoretical. .'. Mathematics are better than logic.

(22) Death must be a good. For either the soul, ceasing to be, ceases ta suffer, or, continuing to be, lives in a better state.

(23) What is right should be enforced by law. .'. Charity should be so enforced.

(24) All animals were in the Ark. .'. No animals perished in the Flood.

(25) If he robs, he is not honourable. If he pays all his dues, he does not rob. .'. If he pays all his dues, he is honourable.

(26) A dove can fly a mile in a minute. A swallow can fly faster than a dove. .'. A swallow can fly more than a mile in a minute.

(27) 'I must soap myself, because it's Sunday.' 'Then do you only soap yourself on Sunday.'

(28) If the charge is false, the author of it is either ignorant or malicious. But the charge is true. Therefore he is neither.

(29) All the angles of a triangle are equal to two right angles. The angle at the vertex is an angle of a triangle. .'. It is equal to two right angles.

(30) Si gravis sit dolor, brevis est; si longus, levis. Ergo fortiter ferendus.

(31) You are not what I am. I am a man. .'. You are not a man.

(32) The extension of the franchise is necessary, for it is imperative that the right of voting should be granted to classes who have hitherto not possessed this privilege.

(33) If Hannibal is really victorious, he does not need supplies; while, if he is deluding us, we ought certainly not to encourage him by sending them. Livy, xxiii. 13. § 5.

(34) Laws must punish, and punishment hurts. All laws therefore are hurtful.

(35) The sun is an insensible thing. The Persians worship the sun. .'. The Persians worship an insensible thing.

(36) Some ores are not metals; for they are not fluids, and some metals are not fluids.

(37) All the Grecian soldiers put the Persians to flight. .'. Every Grecian soldier could rout the Persians.

(38) The resurrection of Jesus Christ is either an isolated fact or else admits of parallel. But if it be an isolated fact, it cannot be rendered probable to one who denies the authority of Christianity; and, if it admit of parallel, it no longer proves what is required. Therefore it is either incapable of being substantiated or else makes nothing for the truth of Christianity.

(39) The resurrection of Christ in the flesh and his ascension into heaven were events either intrinsically incredible in their nature or not. If the former, the prevalent belief in them can only be accounted for by miracles; if the latter, they ought to be believed even without miracles. St. Aug. De Civ. Dei, xxii. 8.

(40) Only contented people are wise. Therefore the tramp contented in his rags is necessarily a wise man.

(41) Four-legged things are brutes. Tables are four-legged things. .'. Tables are brutes.

(42) The apparent volcanoes in the moon are not volcanoes; for eruptions are produced by gases only, and there are no gases in the moon.

(43) To read the Scriptures is our duty. Therefore the Captain was wrong in punishing the helmsman for reading the Bible at the time when the ship struck.

(44) The divine law orders that kings should be honoured. Louis Quatorze is a king. .'. The divine law orders that Louis Quatorze should be honoured.

(45) Those who desire the same object are unanimous. Caesar and Pompey both desire the same object, namely, supreme power. .'. They are unanimous.

(46) Either the ministers left at home will be ciphers or they will not be ciphers. If they are ciphers, cabinet government, which is equivalent to constitutional government, will receive a rude blow. If they are not ciphers, the cabinet will be considering matters of the utmost importance in the absence, and the gratuitous absence, of two of its most important members. 'The Standard,' Wed. June 5, 1878.

(47) One patent stove saves half the ordinary amount of fuel. Therefore two would save it all.

(48) One number must win in the lottery. My ticket is one number. .'. It must win.

(49) All good shepherds are prepared to lay down their lives for the sheep. Few in this age are so prepared. .'. Few in this age are good shepherds.

(50) You cannot define the sun; for a definition must be clearer than the thing defined, and nothing can be clearer than the source of all light.

(51) To give the monopoly of the home market to the produce of domestic industry ... must in almost all cases be either a useless or a hurtful regulation. If the produce of domestic can be brought there as cheap as that of foreign industry, the regulation is evidently useless; if it cannot, it is generally hurtful. Adam Smith, Wealth of Nations, Bk. iv. ch. 2.

(52) Verberare est actio. Ergo et vapulare.

(53) The ages of all the members of this family are over 150. The baby is a member of this family. .'. Its age is over 150.

(54) Romulus must be an historical person; because it is not at all likely that the Romans, whose memory was only burdened with seven kings, should have forgotten the most famous of them, namely, the first.

(55) All scientific treatises that are clear and true deserve attention. Few scientific treatises are clear and true. .'. Few scientific treatises deserve attention.

(56) The Conservative Government is an expensive one; for, on their going out of Office, there was a deficit.

(57) A man is forbidden to marry his brother's wife, or, in other words, a woman is forbidden to marry her husband's brother, that is, a woman is directly forbidden to marry two brothers. Therefore a man may not marry two sisters, so that a man may not marry his wife's sister.

INDEX.

The references refer to the sections.

Abstraction, 97.

Acategorematic words, 71.

Accent, Fallacy of, 855.

Accident, 318.

Accident, Fallacy of, 860.

A dicto secundum quid, Fallacy of, 861.

Amphiboly, Fallacy of, 848.

Antecedent of a complex proposition, 212. of an inference, 428.

A posteriori Truth, 232.

A priori Truth, 231.

'A' Propositions, 260. conversion of, 489.

Arguing in a circle, 882.

Argumentum ad hominem, etc., 867.

Attribute, 81 sqq. Essential and non-essential, 320.

Attributives, 88 sqq.

Basis of Division, 391.

Categorematic words, 71.

Circulus in definiendo, 382.

Common Terms, 105. how formed, 99. nature of, 48.

Complex Proposition, 209. conversion of, 709. conversion by contraposition of, 728. conversion by negation of, 721. divided into conjunctive and disjunctive, 214. permutation of, 718.

Complex Syllogism, 731. mixed form of, 778.

Composition, Fallacy of, 849.

Conception, 33.

Conceptualists, 51.

Conclusion, 540. predicate of, 542. subject of, 542.

Conjunctive Syllogisms, 733. canon of, 742. reduction of partly, 744. partly conjunctive syllogisms as an immediate inference, 753.

Connotation of Terms, 148.

Consequent of a complex proposition, 213. of an inference, 428.

Consequent, Fallacy of, 873.

Contingent, 17.

Contradiction, Law of, 25 sqq.

Contradictory Propositions, 458. Terms, 129.

Contrary Propositions, 458. Terms, 130.

Converse, 480.

Conversion, 479. of complex propositions, 709. by contraposition, 516. illative, 481. by negation, 504. per accidens, 487. simple, 486. rules of, 482.

Convertend, 480.

Correlatives, 142.

Deduction and Induction, difference of, 431 sqq.

Deductive Inference, 442.

Deductive Logic, definition of, 4.

Definition of Terms, 347 sqq. of Aristotle ([Greek: òrismós]), 336. final, 374. nominal, 375. provisional, 374. real, 375. rules of, 378.

Denotation of Terms, 152.

Description, 360.

Designations, 112.

Determination, 167.

Dictum de omni et nullo, 569. de diverso, 641. de exemplo et excepto, 642.

Dilemma, 732, 779. rebutted, 792. reduction of, 796. regarded as an immediate inference, 798.

Disjunctive Syllogism, 760. canon of, 765. reduction of, 766. regarded as an immediate inference, 770.

Distinction, 424.

Distribution of Terms, 274. four rules for, 293.

Divided whole, 393.

Dividing members, 394.

Division, 385 sqq. by dichotomy, 412. rules of, 395.

Division, Fallacy of, 851.

Division of Propositions, 206. of terms, 86. of things, 77.

Enthymeme, incorrectly so-called, 557.

Epicheirema, 803.

Episyllogism, 802.

'E' Propositions, 260. conversion of, 490.

Equivocation, Fallacy of, 845.

Excluded Middle, Law of, 25 sqq., 502.

Extension of Terms, 149 sqq., 166 sqq.

Fallacy, 827 sqq. of ambiguity, 831. definition of, 828. formal, 838. logical, 836. material, 831, 836. of undisturbed middle, 585.

Figure of Speech, Fallacy of, 857.

Figures, of a Syllogism, 558. special canons of, 633. special rules of, 606. special uses of, 648.

Formal Logic, 16.

Four Terms, Fallacy of, 840.

Fundamentum Divisionis, 391.

Generalisation, 168.

Heads of Predicables, 313. as given by Aristotle, 336.

'Ideas' of Plato, 52.

Identity, Law of, 25 sqq.

Ignoratio Elenchi, Fallacy of, 865.

Ignotum per ignotius, 383.

Illicit Process, Fallacy of, 586.

Immediate Inference, 442 sqq. by added determinants, 535. by complex conception, 537. applied to complex propositions, 701.

Immediate Inference, compound forms of, 503. partly conjunctive syllogisms regarded as, 753. by conversion, 479. disjunctive syllogisms regarded as, 770. by opposition, 462. by permutation, 496.

Induction, differing from Deduction, 430 sqq.

Inductive Logic, 2, 204.

Inferences in general, 426. classification of, 441. deductive, 442. inductive, 430.

Intimae species, 405.

Intension of Terms, 150, 166.

Intuition, 232.

Inverse Variation, Law of, 166.

'I' Propositions, 260. conversion of, 490.

'Judgement,' various meanings of, 32, 36.

'Law,' ambiguities of the word, 7 sqq.

Major Premiss, 544.

Major Term, 542.

Many Questions, Fallacy of, 884.

Mediate Inferences or Syllogisms, 444, 540 sqq. axioms of, 576.

Membra Dividentia, 394.

Middle Term, 541. position of, in a syllogism, 563.

Minor Premiss, 545.

Minor Term, 542.

Modality, Question of, 196.

Moods of a Syllogism, 558. determination of the legitimate, 599. subaltern, 628. valid in the Four Figures, 621. mnemonics of, valid in Four Figures, 629.

Name, definition of, 61.

Negative Premisses and Conclusion, Fallacy of, 842.

Nominalists, 50, 54.

Non causa pro causa, Fallacy of, 883.

Opposition, 449 sqq. contradictory, 457. contrary, 454. laws of, 464. subaltern, 456. sub-contrary, 455.

'O' Propositions, 260. conversion of, 491.

Partition, 423.

Permutation, 496 sqq. of Complex Propositions, 718.

Petitio Principii, Fallacy of, 874.

Predicable, 314.

Predicate of a Proposition, 58, 184. read in extension, 307. quantification of, 295 sqq. quantity of, 281, 494.

Predication, 194. in quid or in quale, 332.

Primary Existences, 55.

Problema, the, 556.

Proper Names, 113.

Proposition, 172 sqq. accidental, 238. affirmative, 258. complex or conditional, 209. conjunctive or hypothetical, 214, 704. conversion of, 479. definition of, 178. disjunctive, 214. divisions of, 206. essential, 238. exceptive, 270. exclusive, 266. extensive, 264. general, 251. indefinite, 244. intensive, 264. modal, 205. negative, 258. particular, 240. pure, 205. quality of, 258. quantity of, 246. real or synthetical, 227. simple or categorical, 207. singular, 250. tautologous or identical, 273. universal, 239. verbal or analytical, 224.

Proprium, 336.

Pro-syllogism, 802.

Quaestio, the, 556.

Quality of the matter, 204. of propositions, 258.

Quantification of the Predicate, 295 sqq., 493.

Quantity of propositions, 258. of terms, 148.

Realists, 49.

Real Kinds, 371.

Reasoning or Inference, 35. the canon of, 560. trains of, 800.

Reduction of propositions, 667. of the dilemma, 796. of disjunctive syllogisms, 766. indirect, 691. mnemonics for, 697. ostensive or direct, 673. of partly conjunctive syllogisms, 744.

Relation, immediate inference by, 462. compatible and incompatible, 462.

Science, 20.

Secondary Existences, 55.

Simple Apprehension, 33.

Sorites, the, 807 sqq.

Specialisation, 167.

Subalternant, 458.

Subalternate, 458.

Subalternation, 458.

Subalterns, 458.

Sub-contraries, 458.

Sub-division, 401.

Suppositio Materialis, 76.

Syllogism, 546 sqq. complex, 731. in common discourse, 557. conjunctive, 733. definition of, 552. disjunctive, 760. general rules of, 582. figures of, 560, 563. with three figures, 656. legitimate moods of, 599 sqq. mnemonics for, 598. moods of, 559, 562.

Syncntegorematic words, 70.

Term, 57 sqq. absolute, 140. abstract, 95. analogous, 139. attributive, 88. collective, 118. common, 105. concrete, 96. connotative, 147. contradictory, 129. contrary, 130. definition of, 347.

Terms, distribution of, 275. distributive and collective use of, 119. division of, 86. equivocal, 137. incompatible, 135. individual, 121. major, middle, and minor, 542. negative, 126. non-connotative, 147. positive, 126. privative, 126. quantity of, 148.

Terms, relative, 141. repugnant, 135. singular, 43, 104. subject, 87. undistributed, 277. univocal, 137.

Universals, nature of, 48, 55.

'U' Propositions, 297.

Words, their relation to terms, 65 sqq,

THE END.