Aristotle
as furnishing the basis for astronomical science--stands in marked
contrast with Plato, who rejects this basis, and puts aside, with a
sort of contempt, astronomical observation (Republic, vii. pp.
530-531); treating acoustics also in a similar way. Compare Aristot.
Metaphys. [Greek: L]. p. 1073, a. 6, seq., with the commentary of
Bonitz, p. 506.]
[Footnote 65: Analyt. Prior. I. xxx. p. 46, a. 22-27**: [Greek:
ô(/ste a)\n lêphthê=| ta\ u(pa/rchonta peri\ e(/kaston, ê(me/teron
ê)/dê ta\s a)podei/xeis e(toi/môs e)mphani/zein. ei) ga\r mêde\n
_kata\ tê\n i(stori/an_ paraleiphthei/ê tô=n a)lêthô=s u(parcho/ntôn
toi=s pra/gmasin, e(/xomen peri\ a(/pantos ou(= me\n e)/stin
a)po/deixis, tau/tên eu(rei=n kai\ a)podeiknu/nai, ou(= de\ mê\
pe/phuken a)po/deixis, tou=to poiei=n phanero/n.]
Respecting the word [Greek: i(stori/a]--investigation and record of
matters of fact--the first sentence of Herodotus may be compared with
Aristotle, Histor. Animal. p. 491, a. 12; also p. 757, b. 35;
Rhetoric. p. 1359, b. 32.]
For the fuller development of these important principles, the reader
is referred to the treatise on Dialectic, entitled Topica, which we
shall come to in a future chapter. There is nothing in all
Aristotle's writings more remarkable than the testimony here
afforded, how completely he considered all the generalities of
demonstrative science and deductive reasoning to rest altogether on
experience and inductive observation.
We are next introduced to a comparison between the syllogistic
method, as above described and systematized, and the process called
logical Division into _genera_ and _species_; a process much relied
upon by other philosophers, and especially by Plato. This logical
Division, according to Aristotle, is a mere fragment of the
syllogistic procedure; nothing better than a feeble syllogism.[66]
Those who employed it were ignorant both of Syllogism and of its
conditions. They tried to demonstrate--what never can be
demonstrated--the essential constitution of the subject.[67] Instead
of selecting a middle term, as the Syllogism requires, more universal
than the subject but less universal (or not more so) than the
predicate, they inverted the proper order, and took for their middle
term the highest universal. What really requires to be demonstrated,
they never demonstrated but assume.[68]
[Footnote 66: Analyt. Prior. I. xxxi. p. 46, a. 33. Alexander, in
Scholia, p. 180, a. 14. The Platonic method of [Greek: diai/resis] is
exemplified in the dialogues called Sophistês and Politicus; compare
also Philêbus, c. v., p. 15.]
[Footnote 67: Ibid. p. 46, a. 34: [Greek: prô=ton d' au)to\ tou=to
e)lelê/thei tou\s chrôme/nous au)tê=| pa/ntas, kai\ pei/thein
e)pechei/roun ô(s o)/ntos dunatou= peri\ ou)si/as a)po/deixin
gi/nesthai kai\ tou= ti/ e)stin.]]
[Footnote 68: Ibid. p. 46, b. 1-12.]
Thus, they take the subject man, and propose to prove that man is
mortal. They begin by laying down that man is an animal, and that
every animal is either mortal or immortal. Here, the most universal
term, animal, is selected as middle or as medium of proof; while
after all, the conclusion demonstrated is, not that man is mortal,
but that man is either mortal or immortal. The position that man is
mortal, is assumed but not proved.[69] Moreover, by this method of
logical division, all the steps are affirmative and none negative;
there cannot be any refutation of error. Nor can any proof be given
thus respecting _genus_, or _proprium_, or _accidens_; the _genus_ is
assumed, and the method proceeds from thence to _species_ and
_differentia_. No doubtful matter can be settled, and no unknown
point elucidated by this method; nothing can be done except to
arrange in a certain order what is already ascertained and
unquestionable. To many investigations, accordingly, the method is
altogether inapplicable; while even where it is applicable, it leads
to no useful conclusion.[70]
[Footnote 69: Ibid. p. 46, b. 1-12.]
[Footnote 70: Ibid. b. 26-37. Alexander in Schol. p. 180, b. 1.]
We now come to that which Aristotle indicates as the third section of
this First Book of the Analytica Priora. In the first section he
explained the construction and constituents of Syllogism, the
varieties of figure and mode, and the conditions indispensable to a
valid conclusion. In the second section he tells us where we are to
look for the premisses of syllogisms, and how we may obtain a stock
of materials, apt and ready for use when required. There remains one
more task to complete his plan--that he should teach the manner of
reducing argumentation as it actually occurs (often invalid, and even
when valid, often elliptical and disorderly), to the figures of
syllogism as above set forth, for the purpose of testing its
validity.[71] In performing this third part (Aristotle says) we shall
at the same time confirm and illustrate the two preceding parts; for
truth ought in every way to be consistent with itself.[72]
[Footnote 71: Analyt. Prior. I. xxxii. p. 47, a. 2: [Greek: loipo\n
ga\r e)/ti tou=to tê=s ske/pseôs; ei) ga\r tê/n te ge/nesin tô=n
sullogismô=n theôroi=men kai\ tou= eu(ri/skein e)/choimen du/namin,
e)/ti de\ tou\s gegenême/nous a)nalu/oimen ei)s ta\ proeirême/na
schê/mata, te/los a)\n e)/choi ê( e)x a)rchê=s pro/thesis.]]
[Footnote 72: Ibid. a. 8.]
When a piece of reasoning is before us, we must first try to
disengage the two syllogistic premisses (which are more easily
disengaged than the three terms), and note which of them is universal
or particular. The reasoner, however, may not have set out both of
them clearly: sometimes he will leave out the major, sometimes the
minor, and sometimes, even when enunciating both of them, he will
join with them irrelevant matter. In either of these cases we must
ourselves supply what is wanting and strike out the irrelevant.
Without this aid, reduction to regular syllogism is impracticable;
but it is not always easy to see what the exact deficiency is.
Sometimes indeed the conclusion may follow necessarily from what is
implied in the premisses, while yet the premisses themselves do not
form a correct syllogism; for though every such syllogism carries
with it necessity, there may be necessity without a syllogism. In the
process of reduction, we must first disengage and set down the two
premisses, then the three terms; out of which three, that one which
appears twice will be the middle term. If we do not find one term
twice repeated, we have got no middle and no real syllogism. Whether
the syllogism when obtained will be in the first, second, or third
figure, will depend upon the place of the middle term in the two
premisses. We know by the nature of the conclusion which of the three
figures to look for, since we have already seen what conclusions can
be demonstrated in each.[73]
[Footnote 73: Ibid. a. 10-b. 14.]
Sometimes we may get premisses which look like those of a true
syllogism, but are not so in reality; the major proposition ought to
be an universal, but it may happen to be only indefinite, and the
syllogism will not in all cases be valid; yet the distinction between
the two often passes unnoticed.[74] Another source of fallacy is,
that we may set out the terms incorrectly; by putting (in modern
phrase) the abstract instead of the concrete, or abstract in one
premiss and concrete in the other.[75] To guard against this, we
ought to use the concrete term in preference to the abstract. For
example, let the major proposition be, Health cannot belong to any
disease; and the minor. Disease can belong to any man; _Ergo_, Health
cannot belong to any man. This conclusion seems valid, but is not
really so. We ought to substitute concrete terms to this effect:--It
is impossible that the sick can be well; Any man may be sick; _Ergo_,
It is impossible that any man can be well. To the syllogism, now, as
stated in these concrete terms, we may object, that the major is not
true. A person who is at the present moment sick may at a future time
become well. There is therefore no valid syllogism.[76] When we take
the concrete man, we may say with truth that the two contraries,
health-sickness, knowledge-ignorance, _may_ both alike belong to him;
though not to the same individual at the same time.
[Footnote 74: Ibid. I. xxxiii. p. 47, b. 16-40: [Greek: au(/tê me\n
ou)=n ê( a)pa/tê gi/netai e)n tô=| para\ mikro/n; ôs ga\r ou)de\n
diaphe/ron ei)pei=n _to/de tô=|de u(pa/rchein, ê)\ to/de tô=|de
panti\ u(pa/rchein_, sugchôrou=men.]
M. B. St. Hilaire observes in his note (p. 155): "L'erreur vient
uniquement de ce qu'on confond l'universel et l'indeterminé séparés
par une nuance très faible d'expression, qu'on ne doit pas cependant
negliger." Julius Pacius (p. 264) gives the same explanation at
greater length; but the example chosen by Aristotle ([Greek: o(
A)ristome/nês e)sti\ dianoêto\s A)ristome/nês]) appears open to other
objections besides.]
[Footnote 75: Analyt. Prior. I. xxxiv. p. 48, a. 1-28.]
[Footnote 76: Ibid. a. 2-23. See the Scholion of Alexander, p. 181,
b. 16-27, Brandis.]
Again, we must not suppose that we can always find one distinct and
separate name belonging to each term. Sometimes one or all of the
three terms can only be expressed by an entire phrase or proposition.
In such cases it is very difficult to reduce the reasoning into
regular syllogism. We may even be deceived into fancying that there
are syllogisms without any middle term at all, because there is no
single word to express it. For example, let A represent equal to two
right angles; B, triangle; C, isosceles. Then we have a regular
syllogism, with an explicit and single-worded middle term; A belongs
first to B, and then to C through B as middle term (triangle). But
how do we know that A belongs to B? We know it by demonstration; for
it is a demonstrable truth that every triangle has its three angles
equal to two right angles. Yet there is no other more general truth
about triangles from which it is a deduction; it belongs to the
triangle _per se_, and follows from the fundamental properties of the
figure.[77] There is, however, a middle term in the demonstration,
though it is not single-worded and explicit; it is a declaratory
proposition or a fact. We must not suppose that there can be any
demonstration without a middle term, either single-worded or
many-worded.
[Footnote 77: Ibid. I. xxxv. p. 48, a. 30-39: [Greek: phanero\n o(/ti
to\ me/son ou)ch ou(/tôs a)ei\ lêpte/on ô(s to/de ti, a)ll' e)ni/ote
lo/gon, o(/per sumbai/nei ka)pi\ tou= lechthe/ntos.] A good Scholion
of Philoponus is given, p. 181, b. 28-45, Brand.]
When we are reducing any reasoning to a syllogistic form, and tracing
out the three terms of which it is composed, we must expose or set
out these terms in the nominative case; but when we actually
construct the syllogism or put the terms into propositions, we shall
find that one or other of the oblique cases, genitive, dative, &c.,
is required.[78] Moreover, when we say, 'this belongs to that,' or
'this may be truly predicated of that,' we must recollect that there
are many distinct varieties in the relation of predicate to subject.
Each of the Categories has its own distinct relation to the subject;
predication _secundum quid_ is distinguished from predication
_simpliciter_, simple from combined or compound, &c. This applies to
negatives as well as affirmatives.[79] There will be a material
difference in setting out the terms of the syllogism, according as
the predication is qualified (_secundum quid_) or absolute
(_simpliciter_). If it be qualified, the qualification attaches to
the predicate, not to the subject: when the major proposition is a
qualified predication, we must consider the qualification as
belonging, not to the middle term, but to the major term, and as