The Basic Works of Aristotle (Modern Library Classics) (33 page)

9
     Now while some things have a cause distinct from themselves, others have not. Hence it is evident that there are essential natures which are immediate, that is, are basic premisses; and of these not only
that
they are but also
what
they are must be assumed or revealed in some other way. This too is the actual procedure of the arithmetician, who assumes both the nature and the existence of unit.
(25)
On the other hand, it is possible (in the manner explained) to exhibit through demonstration the essential nature of things which have a ‘middle’,
¹¹
i. e. a cause of their substantial being other than that being itself; but we do not thereby demonstrate it.

10
     Since definition is said to be the statement of a thing’s nature, obviously one kind of definition will be a statement of the meaning of the name, or of an equivalent nominal formula.
(30)
A definition in this sense tells you, e. g. the meaning of the phrase ‘triangular character’.
¹²
When we are aware that triangle exists, we inquire the reason why it exists. But it is difficult thus to learn the definition of things the existence of which we do not genuinely know—the cause of this difficulty being, as we said before,
¹³
that we only know accidentally whether or not the thing exises.
(35)
Moreover, a statement may be a unity in either of two ways, by conjunction, like the
Iliad,
or because it exhibits a single predicate as inhering not accidentally in a single subject.
¹⁴

That then is one way of defining definition. Another kind of definition is a formula exhibiting the cause of a thing’s existence.
[94a]
Thus the former signifies without proving, but the latter will clearly be a
quasi
-demonstration of essential nature, differing from demonstration in the arrangement of its terms. For there is a difference between stating why it thunders, and stating what is the essential nature of thunder; since the first statement will be ‘Because fire is quenched in the clouds’, while the statement of what the nature of thunder is will be ‘The noise of fire being quenched in the clouds’.
(5)
Thus the same statement takes a different form: in one form it is continuous
¹⁵
demonstration, in the other definition. Again, thunder can be defined as noise in the clouds, which is the conclusion of the demonstration embodying essential nature. On the other hand the definition of immediates is an indemonstrable positing of essential nature.
(10)
We conclude then that definition is (
a
) an indemonstrable statement of essential nature, or (
b
) a syllogism of essential nature differing from demonstration in grammatical form, or (
c
) the conclusion of a demonstration giving essential nature.

Our discussion has therefore made plain (1) in what sense and of what things the essential nature is demonstrable,
(15)
and in what sense and of what things it is not; (2) what are the various meanings of the term definition, and in what sense and of what things it proves the essential nature, and in what sense and of what things it does not; (3) what is the relation of definition to demonstration, and how far the same thing is both definable and demonstrable and how far it is not.

11
      We think we have scientific knowledge when we know the cause,
(20)
and there are four causes: (1) the definable form, (2) an antecedent which necessitates a consequent,
¹⁶
(3) the efficient cause, (4) the final cause. Hence each of these can be the middle term of a proof, for
¹⁷
(
a
) though the inference from antecedent to necessary consequent does not hold if only one premiss is assumed—two is the minimum—still when there are two it holds on condition that they have a single common middle term.
(25)
So it is from the assumption
of this single middle term that the conclusion follows necessarily. The following example will also show this.
¹⁸
Why is the angle in a semicircle a right angle?—or from what assumption does it follow that it is a right angle? Thus, let
A
be right angle,
B
the half of two right angles,
C
the angle in a semicircle. Then
B
is the cause in virtue of which
A,
(30)
right angle, is attributable to
C,
the angle in a semicircle, since
B = A
and the other, viz.
C, = B,
for
C
is half of two right angles. Therefore it
is
the assumption of
B,
the half of two right angles, from which it follows that
A
is attributable to
C,
i. e. that the angle in a semicircle is a right angle. Moreover,
B
is identical with (
b
) the defining form of
A,
since it is what
A
’s definition
¹⁹
signifies. Moreover, the formal cause has already been shown to be the middle.
²⁰
(35)
(
c
) ‘Why did the Athenians become involved in the Persian war?’ means ‘What cause originated the waging of war against the Athenians?’ and the answer is, ‘Because they raided Sardis with the Eretrians’, since this originated the war.
[94b]
Let
A
be war,
B
unprovoked raiding,
C
the Athenians. Then
B,
unprovoked raiding, is true of
C,
the Athenians, and
A
is true of
B,
since men make war on the unjust aggressor. So
A,
having war waged upon them,
(5)
is true of
B,
the initial aggressors, and
B
is true of
C,
the Athenians, who were the aggressors. Hence here too the cause—in this case the efficient cause—is the middle term. (
d
) This is no less true where the cause is the final cause. e. g. why does one take a walk after supper? For the sake of one’s health. Why does a house exist? For the preservation of one’s goods. The end in view is in the one case health,
(10)
in the other preservation. To ask the reason why one must walk after supper is precisely to ask to what end one must do it. Let
C
be walking after supper,
B
the non-regurgitation of food,
A
health. Then let walking after supper possess the property of preventing food from rising to the orifice of the stomach,
(15)
and let this condition be healthy; since it seems that
B,
the non-regurgitation of food, is attributable to
C,
taking a walk, and that
A,
health, is attributable to
B.
What, then, is the cause through which
A,
the final cause, inheres in
C
? It is
B,
the non-regurgitation of food; but
B
is a kind of definition of
A,
for
A
will be explained by it. Why is
B
the cause of
A
’s belonging to
C
? Because to be in a condition such as
B
is to be in health.
(20)
The definitions must be transposed, and then
the detail will become clearer. Incidentally, here the order of coming to be is the reverse of what it is in proof through the efficient cause: in the efficient order the middle term must come to be first,
(25)
whereas in the teleological order the minor,
C,
must first take place, and the end in view comes last in time.

The same thing may exist for an end and be necessitated as well. For example, light shines through a lantern (1) because that which consists of relatively small particles necessarily passes through pores larger than those particles—assuming that light does issue by penetration—and (2) for an end,
(30)
namely to save us from stumbling. If, then, a thing can exist through two causes, can it come to be through two causes—as for instance if thunder be a hiss and a roar necessarily produced by the quenching of fire, and also designed, as the Pythagoreans say, for a threat to terrify those that lie in Tartarus? Indeed,
(35)
there are very many such cases, mostly among the processes and products of the natural world; for nature, in different senses of the term ‘nature’, produces now for an end, now by necessity.

Necessity too is of two kinds.
[95a]
It may work in accordance with a thing’s natural tendency, or by constraint and in opposition to it; as, for instance, by necessity a stone is borne both upwards and downwards, but not by the same necessity.

Of the products of man’s intelligence some are never due to chance or necessity but always to an end, as for example a house or a statue; others,
(5)
such as health or safety, may result from chance as well.

It is mostly in cases where the issue is indeterminate (though only where the production does not originate in chance, and the end is consequently good), that a result is due to an end, and this is true alike in nature or in art. By chance, on the other hand, nothing comes to be for an end.

12
      The effect may be still coming to be,
(10)
or its occurrence may be past or future, yet the cause will be the same as when it is actually existent—for it is the middle which is the cause—except that if the effect actually exists the cause is actually existent, if it is coming to be so is the cause, if its occurrence is past the cause is past, if future the cause is future. For example, the moon was eclipsed because the earth intervened, is becoming eclipsed because the earth is in process of intervening,
(15)
will be eclipsed because the earth will intervene, is eclipsed because the earth intervenes.

To take a second example: assuming that the definition of ice is solidified water, let
C
be water,
A
solidified,
B
the middle, which is
the cause, namely total failure of heat. Then
B
is attributed to
C,
and
A,
solidification, to
B:
ice forms when
B
is occurring,
(20)
has formed when
B
has occurred, and will form when
B
shall occur.

This sort of cause, then, and its effect come to be simultaneously when they are in process of becoming, and exist simultaneously when they actually exist; and the same holds good when they are past and when they are future. But what of cases where they are not simultaneous? Can causes and effects different from one another form, as they seem to us to form, a continuous succession,
(25)
a past effect resulting from a past cause different from itself, a future effect from a future cause different from it, and an effect which is coming-to-be from a cause different from and prior to it? Now on this theory it is from the posterior event that we reason (and this though these later events actually have their source of origin in previous events—a fact which shows that also when the effect is coming-to-be we still reason from the posterior event), and from the prior event we cannot reason (we cannot argue that because an event
A
has occurred,
(30)
therefore an event
B
has occurred subsequently to
A
but still in the past—and the same holds good if the occurrence is future)—cannot reason because, be the time interval definite or indefinite, it will never be possible to infer that because it is true to say that
A
occurred, therefore it is true to say that
B,
the subsequent event, occurred; for in the interval between the events, though
A
has already occurred, the latter statement will be false.
(35)
And the same argument applies also to future events; i. e. one cannot infer from an event which occurred in the past that a future event will occur. The reason of this is that the middle must be homogeneous, past when the extremes are past, future when they are future, coming to be when they are coming-to-be, actually existent when they are actually existent; and there cannot be a middle term homogeneous with extremes respectively past and future. And it is a further difficulty in this theory that the time interval can be neither indefinite nor definite,
(40)
since during it the inference will be false.
[95b]
We have also to inquire what it is that holds events together so that the coming-to-be now occurring in actual things follows upon a past event. It is evident, we may suggest, that a past event and a present process cannot be ‘contiguous’, for not even two past events can be ‘contiguous’. For past events are limits and atomic; so just as points are not ‘contiguous’ neither are past events,
(5)
since both are indivisible. For the same reason a past event and a present process cannot be ‘contiguous’, for the process is divisible, the event indivisible. Thus the relation of present process to past event is analogous to that of line to point, since a
process contains an infinity of past events.
(10)
These questions, however, must receive a more explicit treatment in our general theory of change.
²¹

The following must suffice as an account of the manner in which the middle would be identical with the cause on the supposition that coming-to-be is a series of consecutive events: for
²²
in the terms of such a series too the middle and major terms must form an immediate premiss; e. g. we argue that,
(15)
since
C
has occurred, therefore
A
occurred: and
C
’s occurrence was posterior,
A
’s prior; but
C
is the source of the inference because it is nearer to the present moment, and the starting-point of time is the present. We next argue that, since
D
has occurred, therefore
C
occurred. Then we conclude that,
(20)
since
D
has occurred, therefore
A
must have occurred; and the cause is
C,
for since
D
has occurred
C
must have occurred, and since
C
has occurred
A
must previously have occurred.

If we get our middle term in this way, will the series terminate in an immediate premiss, or since, as we said, no two events are ‘contiguous’, will a fresh middle term always intervene because there is an infinity of middles? No: though no two events are ‘contiguous’, yet we must start from a premiss consisting of a middle and the present event as major.
(25)
The like is true of future events too, since if it is true to say that
D
will exist, it must be a prior truth to say that
A
will exist, and the cause of this conclusion is
C;
for if
D
will exist,
C
will exist prior to
D,
and if
C
will exist,
A
will exist prior to it. And here too the same infinite divisibility might be urged,
(30)
since future events are not ‘contiguous’. But here too an immediate basic premiss must be assumed. And in the world of fact this is so: if a house has been built, then blocks must have been quarried and shaped. The reason is that a house having been built necessitates a foundation having been laid, and if a foundation has been laid blocks must have been shaped beforehand.
(35)
Again, if a house will be built, blocks will similarly be shaped beforehand; and proof is through the middle in the same way, for the foundation will exist before the house.

Now we observe in Nature a certain kind of circular process of coming-to-be; and this is possible only if the middle and extreme
terms are reciprocal, since conversion is conditioned by reciprocity in the terms of the proof.
(40)
This—the convertibility of conclusions and premisses—has been proved in our early chapters,
²³
and the circular process is an instance of this.
[96a]
In actual fact it is exemplified thus: when the earth had been moistened an exhalation was bound to rise, and when an exhalation had risen cloud was bound to form, and from the formation of cloud rain necessarily resulted, and by the fall of rain the earth was necessarily moistened: but this was the starting-point,
(5)
so that a circle is completed; for posit any one of the terms and another follows from it, and from that another, and from that again the first.

Some occurrences are universal (for they are, or come-to-be what they are, always and in every case); others again are not always what they are but only as a general rule: for instance,
(10)
not every man can grow a beard, but it is the general rule. In the case of such connexions the middle term too must be a general rule. For if
A
is predicated universally of
B
and
B
of
C, A
too must be predicated always and in every instance of
C,
since to hold in every instance and always is of the nature of the universal.
(15)
But we have assumed a connexion which is a general rule; consequently the middle term
B
must also be a general rule. So connexions which embody a general rule—i. e. which exist or come to be as a general rule—will also derive from immediate basic premisses.