Chapter IX: Topica (7)

[Footnote 438: Ibid. b. 16-22: [Greek: to\ me\n ou)=n pseudê= to\n lo/gon ei)=nai tou= le/gontos a(ma/rtêma ma=llon ê)\ tou= lo/gou, kai\ ou)de\ tou= le/gontos a)ei\ to\ a(ma/rtêma, a)ll' o(/tan lantha/nê| au)to/n, e)pei\ kath' au(to/n _ge pollô=n a)lêthô=n a)podecho/metha ma=llon, a)\n e)x o(/ti ma/lista dokou/ntôn a)nairê=| ti tô=n a)lêthô=n; toiou=tos ga\r ô)\n e(te/rôn a)lêthô=n a)po/deixi/s e)stin_; dei= ga\r tô=n keime/nôn ti mê\ ei)=nai pantelô=s, ô(/st' e)/stai _tou/tou_ a)po/deixis.]]

[Footnote 439: Ibid. b. 22-24.]

In estimating the dialectical value of an argument, therefore, we must first look whether the conclusion is formally valid; next, whether the conclusion is true or false; lastly, what are the premisses from whence it is derived.[440] For, if it be derived from premisses false yet probable, it has logical or dialectical value; while, if derived from premisses true yet improbable, it has none.[441] If derived from premisses both false and improbable, it will of course be worthless; either absolutely in itself, or with reference to the thesis under debate.

[Footnote 440: Ibid. b. 24: [Greek: ô(/ste dê=lon o(/ti prô/tê me\n e)pi/skepsis lo/gou kath' au(to\n ei) sumperai/netai, deute/ra de\ po/teron a)lêthe\s ê)\ pseu=dos; tri/tê d' e)k poi/ôn tinô=n.]]

[Footnote 441: Topic. VIII. xii. p. 162, b. 27: [Greek: ei) me\n ga\r e)k pseudô=n e)ndo/xôn de/, logiko/s, ei) d' e)x o)/ntôn me\n a)do/xôn de/, phau=los], &c.]

Two faults of questioners in Dialectic are dealt with specially by Aristotle:--(1) _Petitio Principii_; (2) _Petitio Contrariorum_. He had touched upon both of them (in the Analytica Priora) as they concerned the demonstrative process, or the proving of truth: he now deals with them as they concern the dialectical process, or the setting out of opinions and probabilities.[442]

[Footnote 442: Ibid. xiii. p. 162, b. 31: [Greek: to\ d' e)n a)rchê=| kai\ ta\ e)nanti/a pô=s ai)tei=tai o( e)rôtô=n, _kat' a)lê/theian_ me\n e)n toi=s A)nalutikoi=s] (Priora, II. xvi.) [Greek: ei)/rêtai, _kata\ do/xan_ de\ nu=n lekte/on.]]

Five distinct modes may be enumerated of committing the fault called _Petitio Principii_:--

1. You may put as a question the very conclusion which it is incumbent on you to prove, in refutation of the thesis of the respondent. If this is done in explicit terms, your opponent can hardly fail to perceive it; but he possibly may fail, if you substitute an equivalent term or the definition in place of the term.[443]

[Footnote 443: Ibid. b. 34. [Greek: prô=ton ei)/ tis au)to\ to\ dei/knusthai de/on ai)tê/sei; tou=to d' e)p' au)tou= me\n ou) r(a/|dion lantha/nein, e)n de\ toi=s sunônu/mois, kai\ e)n o(/sois to\ o)/noma kai\ o( lo/gos to\ au)to\ sêmai/nei, ma=llon.]]

2. If the conclusion which you are seeking to prove is a particular one, you may put as a question the universal in which it is comprised. Thus, if you are to prove that the knowledge of Contraries is one and the same, you may put as a question, Is not the knowledge of Opposites one and the same? You are asking the very point which it was your business to show; but you are asking along with it much more besides.[444]

[Footnote 444: Ibid. p. 163, a. 1.]

3. If you are seeking to prove an universal conclusion, **you may put as a question one of the particulars comprised therein. Thus, if you are to prove that the knowledge of Contraries is one and the same, you may put as a question, Is not the knowledge of white and black, good and evil, or any other pair of particular contraries, one and the same? It was your business to prove this particular, along with many others besides; but you are now asking it as a question separately.[445]

[Footnote 445: Ibid. a. 5.]

4. If the conclusion which you are seeking to prove has two terms conjointly, you may put as a question one or the other of these separately. Thus, when you are trying to show that the healing art is knowledge of what is wholesome and unwholesome, you may ask, Is it a knowledge of the wholesome?[446]

[Footnote 446: Ibid. a. 8.]

5. Suppose there are two conclusions necessarily implicated with each other, and that it is your business to prove one of them: you may put as a question the other of the two. Thus, if you are seeking to prove that the diagonal is incommensurable with the side, you may put as a question, Is not the side incommensurable with the diagonal?[447]

[Footnote 447: Topic. VIII. xiii. p. 163, a. 10.]

There are also five distinct modes of _Petitio Contrariorum_:--

1. You may ask the respondent, in plain terms, to grant first the affirmative, next, the negative, of a given proposition.[448]

[Footnote 448: Ibid. a. 14: [Greek: prô=ton me\n ga\r ei)/ tis ta\s a)ntikeime/nas ai)tê/saito pha/sin kai\ a)nti/phasin.]]

2. You may ask him to grant, first, that a given subject is, _e.g._, good, next, that the same subject is bad.[449]

[Footnote 449: Ibid. a. 16: [Greek: deu/teron de\ ta)nanti/a kata\ tê\n a)nti/thesin, oi(=on a)gatho\n kai\ kako\n tau)to/n.]]

3. After he has granted to you the affirmative universally, you may ask him to grant the negative in some particular case under the universal: _e.g._, after he has granted that the knowledge of Contraries is one and the same, you ask him to grant that the knowledge of wholesome and unwholesome is not one and the same. Or you may proceed by the way of reversing this process.[450]

[Footnote 450: Ibid. a. 17-21.]

4. You may ask the contrary of that which follows necessarily from the premisses admitted.[451]

[Footnote 451: Ibid. a. 21.]

5. Instead of asking the two contraries in plain and direct terms, you may ask the two contraries in different propositions, yet necessarily implicated with the first two.[452]

[Footnote 452: Ibid. a. 22.]

There is this difference between _Petitio Principii_, and _Petitio Contrariorum_: the first has reference to the conclusion which you have to prove, and the wrong procedure involved in it is relative to that conclusion; but in the second the wrong procedure affects only the two propositions themselves and the relation subsisting between them.[453]

[Footnote 453: Ibid. a. 24: [Greek: diaphe/rei de\ to\ ta)nanti/a lamba/nein tou= e)n a)rchê=|, o(/ti tou= me/n e)stin ê( a(marti/a pro\s to\ sumpe/rasma (pro\s ga\r e)kei=no ble/pontes to\ e)n a)rchê=| le/gomen ai)tei=sthai), ta\ d' e)nanti/a e)sti\n e)n tai=s prota/sesi tô=| e)/chein pôs tau/tas pro\s a)llê/las.]]

Aristotle now, finally, proceeds to give some general advice for exercise and practice in Dialectic. You ought to accustom yourself to treat arguments by converting the syllogisms of which they consist; that is, by applying to them the treatment of which the _Reductio ad Absurdum_ is one case.[454] You ought to test every thesis by first assuming it to be true, then assuming it to be false, and following out the consequences on both sides.[455] When you have hunted out each train of arguments, look out at once for the counter-arguments available against it. This will strengthen your power both as questioner and as respondent. It is indeed an exercise so valuable, that you will do well to go through it by yourself, if you have no companion.[456] Put the different trains of argument, bearing on the same thesis, into comparison with each other. A wide command of arguments affirmative as well as negative will serve you well both for attack and for defence.[457]

[Footnote 454: Ibid. xiv. p. 163, a. 29: [Greek: pro\s de\ gumnasi/an kai\ mele/tên tô=n toiou/tôn lo/gôn prô=ton me\n a)ntistre/phein e)thi/zesthai chrê\ tou\s lo/gous.] For _Conversion_ of Syllogism, see p. 174.]

[Footnote 455: Topic. VIII. xiv. p. 163, a. 36: [Greek: pro\s a(/pasa/n te the/sin kai\ o(/ti ou(/tôs kai\ o(/ti ou)ch ou(/tôs to\ e)pichei/rêma skepte/on.]]

[Footnote 456: Ibid. b. 3: [Greek: ka)\n pro\s mêde/na a)/llon e)/chômen, pro\s au(tou/s.]]

[Footnote 457: Ibid. b. 5: [Greek: tou=to ga\r _pro/s te to\ bia/zesthai_ pollê\n eu)pori/an poiei= kai\ pro\s to\ e)le/gchein mega/lên e)/chei boê/theian, o(/tan eu)porê=| tis kai\ o(/ti ou(/tôs kai\ o(/ti ou)ch ou(/tôs; pro\s ta\ e)nanti/a ga\r sumbai/nei poiei=sthai tê\n phulakê/n.]

Instead of [Greek: pro/s te to\ bia/zesthai], ought we not to read here [Greek: pro/s te to\ mê bia/zesthai], taking this verb in the passive sense? Surely [Greek: bia/zesthai] in the active sense gives the same meaning substantially as [Greek: e)le/gchein], which comes afterwards, both of them referring to the assailant or questioner, whereas Aristotle intends here to illustrate the usefulness of the practice to _both_ parties.]

This same accomplishment will be of use, moreover, for acquisitions even in Science and Philosophy. It is a great step to see and grasp in conjunction the trains of reasoning on both sides of the question; the task that remains--right determination which of the two is the better--becomes much easier. To do this well, however,--to choose the true and to reject the false correctly--there must be conjoined a good natural predisposition. None but those who are well constituted by nature, who have their likings and dislikes well set in regard to each particular conjuncture, can judge correctly what is best and what is worst.[458]

[Footnote 458: Ibid. b. 12-16: [Greek: dei= de\ pro\s to\ toiou=to u(pa/rchein eu)phua=; kai\ tou=t' e)/stin ê( kat' a)lê/theian eu)phui+/a, to\ du/nasthai kalô=s e(le/sthai ta)lêthe\s kai\ phugei=n to\ pseu=dos; o(/per oi( pephuko/tes eu)= du/nantai poiei=n; eu)= ga\r philou=ntes kai\ misou=ntes to\ prosphero/menon eu)= kri/nousi to\ be/ltiston.]]

In regard to the primary or most universal theses, and to those problems which are most frequently put in debate, you will do well to have reasonings ready prepared, and even to get them by heart. It is on these first or most universal theses that respondents become often reluctant and disgusted. To be expert in handling primary doctrines and probabilities, and to be well provided with the definitions from which syllogisms must start, is to the dialectician an acquisition of the highest moment; like familiarity with the Axioms to a geometer, and ready application of the multiplication table to an arithmetical calculator.[459] When you have these generalities and major propositions firmly established in your mind, you will recall, in a definite order and arrangement, the particular matters falling under each of them, and will throw them more easily into syllogisms. They will assist you in doing this, just as the mere distribution of places in a scheme for topical memory makes you recollect what is associated with each. You should lodge in your memory, however, universal major premisses rather than complete and ready-made reasonings; for the great difficulty is about the _principia_.[460]

[Footnote 459: Ibid. b. 17-26.]

[Footnote 460: Topic. VIII. xiv. p. 163, b. 27-33: [Greek: o(moi/ôs kai\ e)n toi=s lo/gois to\ pro/cheiron ei)=nai peri\ ta\s a)rcha\s kai\ ta\s prota/seis a)po\ sto/matos e)xepi/stasthai; katha/per ga\r e)n tô=| mnêmonikô=| mo/non oi( to/poi tethe/ntes eu)thu\s poiou=sin au)ta\ mnêmoneu/ein, kai\ tau=ta poiê/sei sullogistikô/teron dia\ to\ pro\s ô(risme/nas au)ta\s ble/pein kat' a)rithmo/n; pro/tasi/n te koinê\n ma=llon ê)\ lo/gon ei)s mnê/mên thete/on; a)rchê=s ga\r kai\ u(pothe/seôs eu)porê=sai metri/ôs chalepo/n.]]

You ought also to accustom yourself to break down one reasoning into many; which will be done most easily when the theme of the reasoning is most universal. Conceal this purpose as well as you can; and in this view begin with those particulars which lie most remote from the subject in hand.[461] In recording arguments for your own instruction, you will generalize them as much as possible, though perhaps when spoken they may have been particular; for this is the best way to break down one into several. In conducting your own case as questioner you will avoid the higher generalities as much as you can.[462] But you must at the same time take care to keep up some common or general premisses throughout the discourse; for every syllogistic process, even where the conclusion is particular, implies this, and no syllogism is valid without it.[463]

[Footnote 461: Ibid. b. 34.]

[Footnote 462: Ibid. p. 164, a. 2-7: [Greek: dei= de\ kai\ ta\s a)pomnêmoneu/seis katho/lou poiei=sthai tô=n lo/gôn, ka)\n ê)=| dieilegme/nos e)pi\ me/rous;--au)to\n de\ o(/ti ma/lista pheu/gein e)pi\ to\ katho/lou phe/rein tou\s sullogismou/s.]

This passage is to me obscure. I have given the best meaning which it seems to offer.]

[Footnote 463: Ibid. a. 8.]

Exercise in inductive discourse is most suitable for a young beginner; exercise in deductive or syllogistic discourse, for skilful veterans. From those who are accomplished in the former you can learn the art of multiplying particular comparisons; from those who are accomplished in the latter you derive universal premisses; such being the strong points of each. When you go through a dialectical exercise, try to bring away with you for future use either some complete syllogism, or some solution of an apparent refutation, or a major premiss, or a well-sustained exceptional example ([Greek: e)/nstasin]); note also whether either you or your respondent question correctly or otherwise, and on what reason such correctness or incorrectness turned.[464] It is the express purpose of dialectical exercise to acquire power and facility in this procedure, especially as regards universal premisses and special exceptions. Indeed the main characteristic of the dialectician is to be apt at universal premisses, and apt at special exceptions. In the first of these two aptitudes he groups many particulars into one universal, without which he cannot make good his syllogism; in the second of the two he breaks up the one universal into many, distinguishing the separate constituents, and denying some while he affirms others.[465]

[Footnote 464: Ibid. a. 12-19. [Greek: o(/lôs d' e)k tou= gumna/zesthai dialego/menon peirate/on a)pophe/resthai ê)\ sullogismo\n peri\ tinos, ê)\ lu/sin ê)\ pro/tasin ê)\ e)/nstasin], &c.]

[Footnote 465: Topic. VIII. xiv. p. 164, b. 2-6: [Greek: e)/sti ga\r ô(s a(plô=s ei)pei=n dialektiko\s o( protatiko\s kai\ e)nstatiko/s; e)/sti de\ to\ me\n protei/nesthai e(\n poiei=n ta\ plei/ô (dei= **ga\r e(\n o(/lôs lêphthê=nai pro\s o(\ o( lo/gos), to\ d' e)ni/stasthai to\ e(\n polla/; ê)\ ga\r diairei= ê)\ a)nairei=, to\ me\n didou\s to\ d' ou)\ tô=n **proteinome/nôn.]]

You must take care however not to carry on this exercise with every one, especially with a vulgar-minded man. With some persons the dispute cannot fail to take a discreditable turn. When the respondent tries to make a show of escaping by unworthy manoeuvres, the questioner on his part must be unscrupulous also in syllogizing; but this is a disgraceful scene. To keep clear of such abusive discourse, you must be cautious not to discourse with commonplace, unprepared, respondents.[466]

[Footnote 466: Ibid. b. 8-15: [Greek: pro\s ga\r to\n pa/ntôs peirô/menon phai/nesthai diapheu/gein, di/kaion me\n pa/ntôs peira=sthai sullogi/sasthai, ou)k eu)/schêmon de/.]]