The Basic Works of Aristotle (Modern Library Classics) (29 page)

BOOK: The Basic Works of Aristotle (Modern Library Classics)
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27
     The science which is knowledge at once of the fact and of the reasoned fact, not of the fact by itself without the reasoned fact, is the more exact and the prior science.

A science such as arithmetic, which is not a science of properties
qua
inhering in a substratum, is more exact than and prior to a science like harmonics, which is a science of properties inhering in a substratum; and similarly a science like arithmetic, which is constituted of fewer basic elements, is more exact than and prior to geometry, which requires additional elements. What I mean by ‘additional elements’ is this: a unit is substance without position,
(35)
while a point is substance with position; the latter contains an additional element.

28
     A single science is one whose domain is a single genus, viz. all the subjects constituted out of the primary entities of the genus—i. e. the parts of this total subject—and their essential properties.

One science differs from another when their basic truths have neither a common source nor are derived those of the one science from those of the other. This is verified when we reach the indemonstrable premisses of a science, for they must be within one genus with its conclusions: and this again is verified if the conclusions proved by means of them fall within one genus—i. e. are homogeneous.
[87b]

29
     One can have several demonstrations of the same connexion not only by taking from the same series of predication middles which are other than the immediately cohering term—e. g. by taking
C, D,
(5)
and
F
severally to prove
A–B
—but also by taking a middle from another series. Thus let
A
be change,
D
alteration of a property,
B
feeling pleasure, and
G
relaxation. We can then without falsehood predicate
D
of
B
and
A
of
D,
for he who is pleased suffers alteration of a property,
(10)
and that which alters a property changes. Again, we can predicate
A
of
G
without falsehood, and
G
of
B;
for to feel pleasure is to relax, and to relax is to change. So the conclusion can be drawn through middles which are different, i. e. not in the same series—yet not so that neither of these middles is predicable of the other, for they must both be attributable to some one subject.
(15)

A further point worth investigating is how many ways of proving the same conclusion can be obtained by varying the figure.

30
     There is no knowledge by demonstration of chance conjunctions; for chance conjunctions exist neither by necessity nor as general connexions but comprise what comes to be as something distinct from these.
(20)
Now demonstration is concerned only with one or other of
these two; for all reasoning proceeds from necessary or general premisses, the conclusion being necessary if the premisses are necessary and general if the premisses are general.
(25)
Consequently, if chance conjunctions are neither general nor necessary, they are not demonstrable.

31
     Scientific knowledge is not possible through the act of perception. Even if perception as a faculty is of ‘the such’ and not merely of a ‘this somewhat’, yet one must at any rate actually perceive a ‘this somewhat’,
(30)
and at a definite present place and time: but that which is commensurately universal and true in all cases one cannot perceive, since it is not ‘this’ and it is not ‘now’; if it were, it would not be commensurately universal—the term we apply to what is always and everywhere. Seeing, therefore, that demonstrations are commensurately universal and universals imperceptible, we clearly cannot obtain scientific knowledge by the act of perception: nay,
(35)
it is obvious that even if it were possible to perceive that a triangle has its angles equal to two right angles, we should still be looking for a demonstration—we should not (as some
48
say) possess knowledge of it; for perception must be of a particular, whereas scientific knowledge involves the recognition of the commensurate universal. So if we were on the moon, and saw the earth shutting out the sun’s light,
(40)
we should not know the cause of the eclipse: we should perceive the present fact of the eclipse, but not the reasoned fact at all, since the act of perception is not of the commensurate universal.
[88a]
I do not, of course, deny that by watching the frequent recurrence of this event we might, after tracking the commensurate universal, possess a demonstration, for the commensurate universal is elicited from the several groups of singulars.
(5)

The commensurate universal is precious because it makes clear the cause; so that in the case of facts like these which have a cause other than themselves universal knowledge
49
is more precious than sense-perceptions and than intuition. (As regards primary truths there is of course a different account to be given.
50
) Hence it is clear that knowledge of things demonstrable cannot be acquired by perception,
(10)
unless the term perception is applied to the possession of scientific knowledge through demonstration. Nevertheless certain points do arise with regard to connexions to be proved which are referred for their explanation to a failure in sense-perception: there are cases
when an act of vision would terminate our inquiry, not because in seeing we should be knowing, but because we should have elicited the universal from seeing; if, for example, we saw the pores in the glass and the light passing through, the reason of the kindling would be clear to us
51
because we should at the same time see it in each instance and intuit that it must be so in all instances.
(15)

32
     All syllogisms cannot have the same basic truths. This may be shown first of all by the following dialectical considerations. (1) Some syllogisms are true and some false: for though a true inference is possible from false premisses,
(20)
yet this occurs once only—I mean if
A,
for instance, is truly predicable of
C,
but
B,
the middle, is false, both
A–B
and
B–C
being false; nevertheless, if middles are taken to prove these premisses, they will be false because every conclusion which is a falsehood has false premisses, while true conclusions have true premisses,
(25)
and false and true differ in kind. Then again, (2) falsehoods are not all derived from a single identical set of principles: there are falsehoods which are the contraries of one another and cannot coexist, e. g. ‘justice is injustice’, and ‘justice is cowardice’; ‘man is horse’, and ‘man is ox’; ‘the equal is greater’, and ‘the equal is less’. From our established principles we may argue the case as follows,
(30)
confining ourselves therefore to true conclusions. Not even all these are inferred from the same basic truths; many of them in fact have basic truths which differ generically and are not transferable; units, for instance, which are without position, cannot take the place of points, which have position. The transferred terms could only fit in as middle terms or as major or minor terms, or else have some of the other terms between them,
(35)
others outside them.

Nor can any of the common axioms—such, I mean, as the law of excluded middle—serve as premisses for the proof of all conclusions. For the kinds of being are different, and some attributes attach to
quanta
and some to
qualia
only; and proof is achieved by means of the common axioms taken in conjunction with these several kinds and their attributes.
[88b]

Again, it is not true that the basic truths are much fewer than the conclusions, for the basic truths are the premisses,
(5)
and the premisses are formed by the apposition of a fresh extreme term or the interposition of a fresh middle. Moreover, the number of conclusions is indefinite, though the number of middle terms is finite; and lastly some of the basic truths are necessary, others variable.

Looking at it in this way we see that, since the number of conclusions is indefinite, the basic truth cannot be identical or limited in number.
(10)
If, on the other hand, identity is used in another sense, and it is said, e. g., ‘these and no other are the fundamental truths of geometry, these the fundamentals of calculation, these again of medicine’; would the statement mean anything except that the sciences have basic truths? To call them identical because they are self-identical is absurd, since everything can be identified with everything in that sense of identity.
(15)
Nor again can the contention that all conclusions have the same basic truths mean that from the mass of all possible premisses any conclusion may be drawn. That would be exceedingly naïve, for it is not the case in the clearly evident mathematical sciences, nor is it possible in analysis, since it is the immediate premisses which are the basic truths, and a fresh conclusion is only formed by the addition of a new immediate premiss: but if it be admitted that it is these primary immediate premisses which are basic truths,
(20)
each subject-genus will provide one basic truth. If, however, it is not argued that from the mass of all possible premisses any conclusion may be proved, nor yet admitted that basic truths differ so as to be generically different for each science, it remains to consider the possibility that, while the basic truths of all knowledge are within one genus, special premisses are required to prove special conclusions.
(25)
But that this cannot be the case has been shown by our proof that the basic truths of things generically different themselves differ generically. For fundamental truths are of two kinds, those which are premisses of demonstration and the subject-genus; and though the former are common, the latter—number, for instance, and magnitude—are peculiar.

33
      Scientific knowledge and its object differ from opinion and the object of opinion in that scientific knowledge is commensurately universal and proceeds by necessary connexions,
(30)
and that which is necessary cannot be otherwise. So though there are things which are true and real and yet can be otherwise,
scientific knowledge
clearly does not concern them; if it did, things which can be otherwise would be incapable of being otherwise.
(35)
Nor are they any concern of
rational intuition
—by rational intuition I mean an originative source of scientific knowledge—nor of indemonstrable knowledge, which is the grasping of the immediate premiss.
[89a]
Since then rational intuition, science, and opinion, and what is revealed by these terms, are the only things that can be ‘true’, it follows that it is
opinion
that is concerned with that which may be true or false, and can be otherwise:
opinion in fact is the grasp of a premiss which is immediate but not necessary. This view also fits the observed facts, for opinion is unstable,
(5)
and so is the kind of being we have described as its object. Besides, when a man thinks a truth incapable of being otherwise he always thinks that he knows it, never that he opines it. He thinks that he opines when he thinks that a connexion, though actually so, may quite easily be otherwise; for he believes that such is the proper object of opinion, while the necessary is the object of knowledge.
(10)

In what sense, then, can the same thing be the object of both opinion and knowledge? And if any one chooses to maintain that all that he knows he can also opine, why should not opinion be knowledge? For he that knows and he that opines will follow the same train of thought through the same middle terms until the immediate premisses are reached; because it is possible to opine not only the fact but also the reasoned fact,
(15)
and the reason is the middle term; so that, since the former knows, he that opines also has knowledge.

The truth perhaps is that if a man grasp truths that cannot be other than they are, in the way in which he grasps the definitions through which demonstrations take place, he will have not opinion but knowledge: if on the other hand he apprehends these attributes as inhering in their subjects, but not in virtue of the subjects’ substance and essential nature, he possesses opinion and not genuine knowledge; and his opinion,
(20)
if obtained through immediate premisses, will be both of the fact and of the reasoned fact; if not so obtained, of the fact alone. The object of opinion and knowledge is not quite identical; it is only in a sense identical, just as the object of true and false opinion is in a sense identical. The sense in which some maintain that true and false opinion can have the same object leads them to embrace many strange doctrines,
(25)
particularly the doctrine that what a man opines falsely he does not opine at all. There are really many senses of ‘identical’, and in one sense the object of true and false opinion can be the same, in another it cannot. Thus, to have a true opinion that the diagonal is commensurate with the side would be absurd: but because the diagonal with which they are both concerned is the same,
(30)
the two opinions have objects so far the same: on the other hand, as regards their essential definable nature these objects differ. The identity of the objects of knowledge and opinion is similar. Knowledge is the apprehension of, e. g. the attribute ‘animal’ as incapable of being otherwise, opinion the apprehension of ‘animal’ as capable of being otherwise—e. g. the apprehension that animal is an element in the essential nature of man is knowledge; the apprehension of animal as predicable of man but not as an element in
man’s essential nature is opinion: man is the subject in both judgments,
(35)
but the mode of inherence differs.

This also shows that one cannot opine and know the same thing simultaneously; for then one would apprehend the same thing as both capable and incapable of being otherwise—an impossibility.
[89b]
Knowledge and opinion of the same thing can coexist in two different people in the sense we have explained, but not simultaneously in the same person. That would involve a man’s simultaneously apprehending, e. g., (1) that man is essentially animal—i. e. cannot be other than animal—and (2) that man is not essentially animal,
(5)
that is, we may assume, may be other than animal.

Further consideration of modes of thinking and their distribution under the heads of discursive thought, intuition, science, art, practical wisdom, and metaphysical thinking, belongs rather partly to natural science, partly to moral philosophy.

BOOK: The Basic Works of Aristotle (Modern Library Classics)
5.48Mb size Format: txt, pdf, ePub
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