Aristotle

by Various Works [lit]

  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