the knowledge of opposites in general is one: for then he is generally
thought to be begging, along with a number of other things, that which
he ought to have shown by itself. A third way is if any one were to
beg in particular cases what he undertakes to show universally: e.g.
if he undertook to show that the knowledge of contraries is always
one, and begged it of certain pairs of contraries: for he also is
generally considered to be begging independently and by itself what,
together with a number of other things, he ought to have shown. Again,
a man begs the question if he begs his conclusion piecemeal: supposing
e.g. that he had to show that medicine is a science of what leads to
health and to disease, and were to claim first the one, then the
other; or, fifthly, if he were to beg the one or the other of a pair
of statements that necessarily involve one other; e.g. if he had to
show that the diagonal is incommensurable with the side, and were to
beg that the side is incommensurable with the diagonal.
The ways in which people assume contraries are equal in number to
those in which they beg their original question. For it would
happen, firstly, if any one were to beg an opposite affirmation and
negation; secondly, if he were to beg the contrary terms of an
antithesis, e.g. that the same thing is good and evil; thirdly,
suppose any one were to claim something universally and then proceed
to beg its contradictory in some particular case, e.g. if having
secured that the knowledge of contraries is one, he were to claim that
the knowledge of what makes for health or for disease is different;
or, fourthly, suppose him, after postulating the latter view, to try
to secure universally the contradictory statement. Again, fifthly,
suppose a man begs the contrary of the conclusion which necessarily
comes about through the premisses laid down; and this would happen
suppose, even without begging the opposites in so many words, he
were to beg two premisses such that this contradictory statement
that is opposite to the first conclusion will follow from them. The
securing of contraries differs from begging the original question in
this way: in the latter case the mistake lies in regard to the
conclusion; for it is by a glance at the conclusion that we tell
that the original question has been begged: whereas contrary views lie
in the premisses, viz. in a certain relation which they bear to one
another.
14
The best way to secure training and practice in arguments of this
kind is in the first place to get into the habit of converting the
arguments. For in this way we shall be better equipped for dealing
with the proposition stated, and after a few attempts we shall know
several arguments by heart. For by 'conversion' of an argument is
meant the taking the reverse of the conclusion together with the
remaining propositions asked and so demolishing one of those that were
conceded: for it follows necessarily that if the conclusion be untrue,
some one of the premisses is demolished, seeing that, given all the
premisses, the conclusion was bound to follow. Always, in dealing with
any proposition, be on the look-out for a line of argument both pro
and con: and on discovering it at once set about looking for the
solution of it: for in this way you will soon find that you have
trained yourself at the same time in both asking questions and
answering them. If we cannot find any one else to argue with, we
should argue with ourselves. Select, moreover, arguments relating to
the same thesis and range them side by side: for this produces a
plentiful supply of arguments for carrying a point by sheer force, and
in refutation also it is of great service, whenever one is well
stocked with arguments pro and con: for then you find yourself on your
guard against contrary statements to the one you wish to secure.
Moreover, as contributing to knowledge and to philosophic wisdom the
power of discerning and holding in one view the results of either of
two hypotheses is no mean instrument; for it then only remains to make
a right choice of one of them. For a task of this kind a certain
natural ability is required: in fact real natural ability just is
the power right to choose the true and shun the false. Men of
natural ability can do this; for by a right liking or disliking for
whatever is proposed to them they rightly select what is best.
It is best to know by heart arguments upon those questions which are
of most frequent occurrence, and particularly in regard to those
propositions which are ultimate: for in discussing these answerers
frequently give up in despair. Moreover, get a good stock of
definitions: and have those of familiar and primary ideas at your
fingers' ends: for it is through these that reasonings are effected.
You should try, moreover, to master the heads under which other
arguments mostly tend to fall. For just as in geometry it is useful to
be practised in the elements, and in arithmetic to have the
multiplication table up to ten at one's fingers' ends-and indeed it
makes a great difference in one's knowledge of the multiples of
other numbers too-likewise also in arguments it is a great advantage
to be well up in regard to first principles, and to have a thorough
knowledge of premisses at the tip of one's tongue. For just as in a
person with a trained memory, a memory of things themselves is
immediately caused by the mere mention of their loci, so these
habits too will make a man readier in reasoning, because he has his
premisses classified before his mind's eye, each under its number.
It is better to commit to memory a premiss of general application than
an argument: for it is difficult to be even moderately ready with a
first principle, or hypothesis.
Moreover, you should get into the habit of turning one argument into
several, and conceal your procedure as darkly as you can: this kind of
effect is best produced by keeping as far as possible away from topics
akin to the subject of the argument. This can be done with arguments
that are entirely universal, e.g. the statement that 'there cannot
be one knowledge of more than one thing': for that is the case with
both relative terms and contraries and co-ordinates.
Records of discussions should be made in a universal form, even
though one has argued only some particular case: for this will
enable one to turn a single rule into several. A like rule applies
in Rhetoric as well to enthymemes. For yourself, however, you should
as far as possible avoid universalizing your reasonings. You should,
moreover, always examine arguments to see whether they rest on
principles of general application: for all particular arguments really
reason universally, as well, i.e. a particular demonstration always
contains a universal demonstration, because it is impossible to reason
at all without using universals.
You should display your training in inductive reasoning against a
young man, in deductive against an expert. You should try
, moreover,
to secure from those skilled in deduction their premisses, from
inductive reasoners their parallel cases; for this is the thing in
which they are respectively trained. In general, too, from your
exercises in argumentation you should try to carry away either a
syllogism on some subject or a refutation or a proposition or an
objection, or whether some one put his question properly or improperly
(whether it was yourself or some one else) and the point which made it
the one or the other. For this is what gives one ability, and the
whole object of training is to acquire ability, especially in regard
to propositions and objections. For it is the skilled propounder and
objector who is, speaking generally, a dialectician. To formulate a
proposition is to form a number of things into one-for the
conclusion to which the argument leads must be taken generally, as a
single thing-whereas to formulate an objection is to make one thing
into many; for the objector either distinguishes or demolishes, partly
granting, partly denying the statements proposed.
Do not argue with every one, nor practise upon the man in the
street: for there are some people with whom any argument is bound to
degenerate. For against any one who is ready to try all means in order
to seem not to be beaten, it is indeed fair to try all means of
bringing about one's conclusion: but it is not good form. Wherefore
the best rule is, not lightly to engage with casual acquaintances,
or bad argument is sure to result. For you see how in practising
together people cannot refrain from contentious argument.
It is best also to have ready-made arguments relating to those
questions in which a very small stock will furnish us with arguments
serviceable on a very large number of occasions. These are those
that are universal, and those in regard to which it is rather
difficult to produce points for ourselves from matters of everyday
experience.
THE END
.
350 BC
ON YOUTH AND OLD AGE, ON LIFE AND DEATH,
ON BREATHING
by Aristotle
translated by G. R. T. Ross
1
WE must now treat of youth and old age and life and death. We must
probably also at the same time state the causes of respiration as
well, since in some cases living and the reverse depend on this.
We have elsewhere given a precise account of the soul, and while
it is clear that its essential reality cannot be corporeal, yet
manifestly it must exist in some bodily part which must be one of
those possessing control over the members. Let us for the present
set aside the other divisions or faculties of the soul (whichever of
the two be the correct name). But as to being what is called an animal
and a living thing, we find that in all beings endowed with both
characteristics (viz. being an animal and being alive) there must be a
single identical part in virtue of which they live and are called
animals; for an animal qua animal cannot avoid being alive. But a
thing need not, though alive, be animal, for plants live without
having sensation, and it is by sensation that we distinguish animal
from what is not animal.
This organ, then, must be numerically one and the same and yet
possess multiple and disparate aspects, for being animal and living
are not identical. Since then the organs of special sensation have one
common organ in which the senses when functioning must meet, and
this must be situated midway between what is called before and
behind (we call 'before' the direction from which sensation comes,
'behind' the opposite), further, since in all living things the body
is divided into upper and lower (they all have upper and lower
parts, so that this is true of plants as well), clearly the
nutritive principle must be situated midway between these regions.
That part where food enters we call upper, considering it by itself
and not relatively to the surrounding universe, while downward is that
part by which the primary excrement is discharged.
Plants are the reverse of animals in this respect. To man in
particular among the animals, on account of his erect stature, belongs
the characteristic of having his upper parts pointing upwards in the
sense in which that applies to the universe, while in the others these
are in an intermediate position. But in plants, owing to their being
stationary and drawing their sustenance from the ground, the upper
part must always be down; for there is a correspondence between the
roots in a plant and what is called the mouth in animals, by means
of which they take in their food, whether the source of supply be
the earth or each other's bodies.
2
All perfectly formed animals are to be divided into three parts, one
that by which food is taken in, one that by which excrement is
discharged, and the third the region intermediate between them. In the
largest animals this latter is called the chest and in the others
something corresponding; in some also it is more distinctly marked off
than in others. All those also that are capable of progression have
additional members subservient to this purpose, by means of which they
bear the whole trunk, to wit legs and feet and whatever parts are
possessed of the same powers. Now it is evident both by observation
and by inference that the source of the nutritive soul is in the midst
of the three parts. For many animals, when either part-the head or the
receptacle of the food-is cut off, retain life in that member to which
the middle remains attached. This can be seen to occur in many
insects, e.g. wasps and bees, and many animals also besides insects
can, though divided, continue to live by means of the part connected
with nutrition.
While this member is indeed in actuality single, yet potentially
it is multiple, for these animals have a constitution similar to
that of Plants; plants when cut into sections continue to live, and
a number of trees can be derived from one single source. A separate
account will be given of the reason why some plants cannot live when
divided, while others can be propagated by the taking of slips. In
this respect, however, plants and insects are alike.
It is true that the nutritive soul, in beings possessing it, while
actually single must be potentially plural. And it is too with the
principle of sensation, for evidently the divided segments of these
animals have sensation. They are unable, however, to preserve their
constitution, as plants can, not possessing the organs on which the
continuance of life depends, for some lack the means for seizing,
others for receiving their food; or again they may be destitute of
other organs as well.
Divisible animals are like a number of animals grown together, but
animals of superior construction behave differently because their
constitution is a unity of the highest possible kind. Hence some of
the organs on division display slight sensitiveness because they
retain some psychi
cal susceptibility; the animals continue to move
after the vitals have been abstracted: tortoises, for example, do so
even after the heart has been removed.
3
The same phenomenon is evident both in plants and in animals, and in
plants we note it both in their propagation by seed and in grafts
and cuttings. Genesis from seeds always starts from the middle. All
seeds are bivalvular, and the place of junction is situated at the
point of attachment (to the plant), an intermediate part belonging
to both halves. It is from this part that both root and stem of
growing things emerge; the starting-point is in a central position
between them. In the case of grafts and cuttings this is
particularly true of the buds; for the bud is in a way the
starting-point of the branch, but at the same time it is in a
central position. Hence it is either this that is cut off, or into
this that the new shoot is inserted, when we wish either a new
branch or a new root to spring from it; which proves that the point of
origin in growth is intermediate between stem and root.
Likewise in sanguineous animals the heart is the first organ
developed; this is evident from what has been observed in those
cases where observation of their growth is possible. Hence in
bloodless animals also what corresponds to the heart must develop
first. We have already asserted in our treatise on The Parts of
Animals that it is from the heart that the veins issue, and that in
sanguineous animals the blood is the final nutriment from which the
members are formed. Hence it is clear that there is one function in
nutrition which the mouth has the faculty of performing, and a
different one appertaining to the stomach. But it is the heart that
has supreme control, exercising an additional and completing function.
Hence in sanguineous animals the source both of the sensitive and of
the nutritive soul must be in the heart, for the functions relative to