Aristotle
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