Miscellanies 8.2.3–8.7.22

What other method, then, could be better or clearer for the beginning of such teaching than to go through the term proposed by an account so clear that all who speak the same language follow? Is the name “demonstration,” then, like “blityri,” a mere sound signifying nothing? And how is it that neither the philosopher nor the orator, nor even the judge, brings forward demonstration as a name without meaning, and none of the litigants is ignorant of what it signifies, as though nothing answered to it? Indeed, the philosophers supply demonstration as something that really exists, each in his own way. Concerning everything under inquiry, then, if one would judge rightly, one would lead the argument back to no other agreed starting point than what all who share the same nation and language agree is signified by the term. Then, setting out from there, one must inquire whether the thing signified, which the argument concerns, exists or not; and next, if it should be shown to exist, one must inquire precisely into its nature, what sort it is, and whether it perhaps oversteps the order assigned to it.

But since it is not enough simply to state one's opinion about what is under inquiry (for the opponent may equally declare in reply whatever he wishes), what is said must be confirmed. If its judgment is referred to something equally disputed, and that again likewise to another disputed thing, it will go on to infinity and be undemonstrable; but if the confirmation of what is not agreed is referred to something agreed by all, that must be made the starting point of the teaching. Every term put forward, then, must be translated into an account that is agreed and clear to those who share in the inquiry, which will be the beginning of the teaching and will guide the discovery of what is sought. Let the name “sun,” then, be put forward. The Stoics say that it is “an intelligent kindling from the waters of the sea.” Is not this account more obscure than the name itself, needing another demonstration to show whether it is true? It is better, then, to say in a common and clear account that the sun is so named as “the brightest of the bodies that move in the heavens”; for this account, I think, is more credible and clearer, and agreed by all alike.

In the same way all people would agree that demonstration is an account that supplies conviction about disputed matters from agreed ones. Not only demonstration, conviction, and knowledge, but also foreknowledge is spoken of in two ways: one scientific and secure, the other merely hopeful. Demonstration in the most proper sense, then, is that which plants scientific conviction in the souls of learners; the other kind rests on opinion. So too with a human being: one is truly a human being, the one who possesses common sense, another is wild and bestial. Thus the comic poet said: “How charming a thing is a human being, when he is a human being.” And of an ox, a horse, and a dog the same account holds, according to the animal's excellence or badness. For looking to the perfection of the kind, we come to the most proper of the meanings. So we understand a physician to be one who lacks nothing of the power of medicine, and the one who knows to be one who lacks nothing of scientific knowledge.

Indication differs from syllogism in that what is indicated is a sign of one thing, being itself also one, as we say that pregnancy is an indication that a woman is no longer a virgin; but what is taken by syllogism, being one, follows from several things, as in the case of Python's betraying the Byzantines, if that is how it happened: not one sign but several are taken. And to conclude from agreed premises is to syllogize; but to conclude something from true premises is to demonstrate. So the benefit of demonstration is compound: it comes from taking premises that are true with respect to what is sought, and from drawing the conclusion that follows from them. If either the first is lacking or the second does not follow from it, one has not demonstrated, though one has syllogized. For to draw the proper conclusion from the premises is only to syllogize; but that each of the premises is also true is not only to have syllogized but also to have demonstrated. To conclude (περαίνειν) is, as is clear from the word itself, to bring to the end (πέρας); and the end in every argument is what is sought, which is also called the conclusion (συμπέρασμα). No single, primary statement is called a syllogism, even if it is true; it is compounded of at least three such statements, two as premises and one as conclusion. Either all things need demonstration, or some are credible of themselves.

But if the former, then by asking for a demonstration of each demonstration we shall go on to infinity, and so demonstration will be overturned; but if the latter, these very things that are credible of themselves will become the starting points of demonstrations. Indeed, the philosophers agree that the first principles of all things are undemonstrable. So if there is demonstration at all, there must of all necessity first be something credible of itself, which is called first and undemonstrable. All demonstration, then, is traced back to undemonstrated faith. There may also be other starting points of demonstrations after the source that springs from faith: the things plainly evident to sense and to thought. For the things that present themselves to sense are simple and not further analyzable; those that present themselves to thought are simple, rational, and first; and the compound things generated from them are no less evident and credible, and more rational than the first. Of what follows and what conflicts, then, … is the power proper to reason, which we all have by nature. If, then, an account is found such that it can supply conviction to what is not yet credible from what is already credible, we shall say that this very thing is the essence of demonstration. It has been said that the kind that belongs to conviction and the kind that belongs to demonstration are both twofold: the one produces only persuasion in the souls of the hearers, the other produces scientific knowledge. If, then, one begins from what is evident to sense and thought, and then draws the proper conclusion, one truly demonstrates; but if one begins only from reputable opinions, and not from first things, that is, from things evident neither to sense nor to thought, then if one draws the proper conclusion one will syllogize, but will not make the demonstration scientific; and if not the proper conclusion, one will not even syllogize at all.

Demonstration differs from analysis. For each thing demonstrated is demonstrated through certain other things demonstrated, these too having been demonstrated beforehand by others, until we run back to things credible of themselves or to things evident to sense and thought; this is called analysis. Demonstration, on the other hand, is when one arrives from first things at what is sought through all the intermediate steps. The man skilled in demonstration, then, must take great care for the truth of the premises, but give no thought to the names, whether one chooses to call them axioms or propositions or premises. Likewise he must take equally great care about what is concluded from what is laid down, and trouble himself very little whether one chooses to call the argument concluding, conclusive, or syllogistic. For I say that in every case the demonstrator must keep these two things: to take true premises, and to draw from them the conclusion that follows, which some also call the inference (ἐπιφορά), that which is brought upon the premises. Concerning everything sought, in each problem there is need of various premises, but ones proper to the problem put forward; and the thing put forward must itself be translated into an account, and this account should be agreed by all. If the premises taken are not proper to the problem, it is not possible rightly … to find out anything about it, since the nature of the whole problem, which is also called the question, is unknown. In all matters under inquiry, then, there is something known beforehand (which, being entirely credible of itself, is believed without demonstration), and this must be made the starting point of the inquiry into them and the criterion of what seems to have been found.

For every inquiry finds its answer on the basis of knowledge that already exists; and the knowledge that exists beforehand of any object of inquiry may sometimes be of the substance alone, while its works are unknown, as with stones, plants, and animals whose activities we do not know, or their affections or powers, or, in a word, the attributes that belong to beings; sometimes one of these powers or affections, or some of them, is known, as the desires and passions of the soul, while the substance is unknown and is the object of inquiry; and in many cases, when our own thought sets all these before itself, the inquiry is to which of the substances it might belong in this way. For having taken the notions of both, the substance and the activity, into the mind, we thus come to the inquiry. And there are cases in which, knowing the activities together with the substances, we are ignorant of the affections. The method of discovery, then, is as follows: we must begin by recognizing the problems themselves. For often the form of the expression deceives, confuses, and disturbs the mind, so that it does not easily find to what kind the problem belongs; for example, whether what is conceived in the womb is an animal. For, having some notion both of “animal” and of “what is conceived,” we inquire whether being an animal belongs to what is conceived, that is, whether the power to move, and further to perceive, belongs to the conceived substance. So the inquiry concerns activities and affections, the substance being known beforehand.

We must therefore at once ask the one who poses the question in turn what he calls an animal; this must be done especially when we see the name carried into different uses; and we must investigate whether what the term signifies is disputed or agreed by all. For if he should say that he calls an animal whatever grows and is nourished, we shall ask him further whether he also considers plants to be animals; and then, if he says so, one must next show that what is conceived grows and is nourished. For Plato calls plants too animals, sharing only in “the third form of soul,” the appetitive; Aristotle thinks that plants share in the vegetative and nutritive soul, but does not think fit to call them animals, for he thinks that only what shares in the other soul, the perceptive, deserves to be called an animal; and the Stoics do not even call the vegetative power a soul. But if the questioner denies that plants too are animals, we shall show that he contradicts himself. For having defined the animal by being nourished and growing, and yet declaring that the plant is not an animal, he seems to say nothing other than that what is nourished and grows both is and is not an animal. Let him say, then, what he wants to learn: whether what is in the womb grows and is nourished, or whether it has some share in perception or also in motion by impulse. For according to Plato the plant is ensouled and an animal; according to Aristotle it is not yet an animal, since it lacks the perceptive faculty, but it is already ensouled (for him, at any rate, the animal is an ensouled, perceptive substance); according to the Stoics the plant is neither ensouled nor an animal, for the animal is an ensouled substance.

If, then, the animal is ensouled, and soul is a perceptive nature, it is clear that what is ensouled is already perceptive. If, then, the questioner, asked in return whether what is in the womb is an animal, should say that he calls an animal what is nourished and grows, he has his answer; but if he should say that what he is asking is whether what is conceived is already perceptive, or also capable of moving itself by some impulse, then the investigation of the matter becomes clear, since the deception about the name no longer remains. But if he does not answer what he was asked in return, and is unwilling to say what he has in mind, or of what thing he predicates the name “animal” when he made his proposition, but bids us make the distinctions ourselves, he would be recognized as contentious. And if, there being two methods, one by question and answer and the other by continuous exposition, he has refused the one, let him listen while we go through everything bearing on the problem; then, when we have finished, he will be free to take up each point in turn.

But if he tries to cut the examination short by asking questions, it is clear that he does not even want to listen. But if he chooses to answer, first of all we must ask him to what thing he applies the name “animal”; and when he has answered this, we must ask again what “what is conceived” or “what is in the womb” signifies to him: whether by “what is in the womb” he means also the things not yet formed and the seed itself that has been deposited, or only what is already articulated and formed, the so-called embryos. When he has answered this too, one must then conclude and teach the matter at hand in order. But if he wants us to speak without answering himself, let him hear: “Since you are unwilling to say of what signified thing you are speaking in what you proposed (for then I would not be arguing about meanings but would already be examining the things themselves), know that you have done something like this: as if you had proposed whether the dog is an animal. For I might reasonably say, ‘What sort of dog?’ For I will go through the land dog and the sea dog and the star in the heavens, and also Diogenes and the other dogs in turn. For I could not divine whether you are asking about all or about one. What you will do later, then, do now: say clearly which one you are inquiring about. But if you are twisting about names, then the very name ‘what is conceived’ is plainly, to everyone, neither an animal nor a plant, but a name and a sound and a body and a being and a something, and anything rather than an animal. And if this is what you proposed, you have your answer.”

Nor, indeed, is what is signified by the name “what is conceived” an animal; that is incorporeal, a sayable, a matter, a thought, and anything rather than an animal. The nature of the animal would be something else; for it was clearly shown to belong to the very thing under inquiry, I mean the nature of the embryo, what sort it is, while the question about what is signified by the name “animal” is a different problem. I say, then: if you call an animal that which can perceive and move by impulse, an animal is not simply what is moving by impulse and perceiving (for it can also sleep, or not perceive when objects of sense are not present); rather, what is naturally able to exercise impulse or also to perceive is the mark of an animal. For something of this sort is signified by these words. First, whether what is conceived can already perceive or move by impulse, which is what is proposed for examination. Second, whether what is conceived will at some time be able to perceive or move by impulse, a sense in which no one inquires, since it is evident. The question was whether the embryo is already an animal or still a plant. And then the name “animal” was translated into an account, so that it might be clear, since we found that it differs from what is not an animal by perception and by motion according to impulse. Again, we distinguished this from the things adjacent to it, saying that one thing is what is such potentially, which is not yet perceiving and moving but will at some time be such, and another is what is already such in actuality; and of the latter, one is already active, while another can be active but is at rest or asleep. It is this that is under inquiry. For the embryo is not to be called an animal because it is nourished; that is the view of those who depart from the essence of what is sought and turn their attention to what is otherwise incidental.

Demonstration is appointed as common to all things said to be found: it is an account that confirms one thing from others. The things from which what is sought is to be confirmed must be agreed upon and known by the learner; and the starting point of all these is what is evident to sense and thought. The first demonstration, then, is composed of these; while one that, from things already demonstrated, concludes something further by means of the first is no less credible than the former, but cannot be called first, because it is not concluded from first propositions. Of the three kinds of difference among the things sought, then, the first has been shown: I mean that, while the substance is known, some of its works or affections are unknown. The second kind of problem was that in which we all know the works and affections but are ignorant of the substance, for example, in what part of the body the ruling faculty of the soul is.

The same attempt at demonstration applies to the third problem as well. Some say, then, that one animal cannot have several ruling principles. Now several principles of the same kind cannot belong to one animal, but there is nothing absurd in its having principles that differ in kind. Against the Pyrrhonists. If suspension of judgment says that nothing is certain, it is clear that it will begin with itself and first invalidate itself. Either, then, it grants that something is true and that one need not suspend judgment about everything, or it persists in saying that nothing is true, and then clearly it will not itself be true in the first place. For either it speaks truly or it does not. If it speaks truly, it grants, against its will, that something is true; if it does not speak truly, it leaves true the things it wished to abolish. For insofar as the suspension that abolishes is shown to be false, in that very respect the things abolished are shown to be true, like the dream that says all dreams are false. For being destructive of itself, it becomes confirmatory of the others. And in general, if it is true, it will make its beginning with itself, being a suspension not of anything else but first of itself. Then, if someone apprehends that he is a man, or that he is suspending judgment, he is plainly not suspending judgment. And how could he have entered into the dispute at all, if he suspends judgment about everything? And how could he answer what was asked? For about this very thing he is plainly not suspending judgment. Indeed he even declares that he suspends judgment. Therefore, if we must obey them and suspend judgment about everything, we shall first suspend judgment about suspension itself, whether it is to be believed or not.

Further, if the truth is just this, not to know the truth, then from the start nothing true is granted by him. But if he says that this too, ignorance of the truth, is disputable, in this very thing he grants that the truth is knowable, in that he evidently does not affirm his suspension about it. A school is an inclination toward doctrines, or, as some say, an inclination toward many doctrines that have coherence with one another and with appearances, tending toward living well. And a doctrine is a rational apprehension; and apprehension is a state and an assent of the mind. Not only those who suspend judgment, but every dogmatist too is accustomed to suspend judgment on some matters, either from weakness of mind, or from the obscurity of the things, or from the equal force of the arguments. The approaches to inquiries and their starting points concern these things and are found in them.

Before definitions, demonstrations, and divisions, one must first set out in how many ways the thing sought is spoken of; homonyms must be dealt with, and synonyms arranged distinctly according to their meanings. Then one must inquire whether the thing proposed is among those considered in relation to others or is taken by itself. After this: whether it is, what it is, what belongs to it incidentally; or also thus: whether it is, what it is, why it is. Toward the study of these, knowledge of particulars and of universals contributes, as do prior things and the divisions of them according to their differences. Induction, then, yields the universal and the definition; divisions yield the species, the essence, and the individual; the study of the number of meanings yields the grasp of the proper sense; and the working through of difficulties increases the differences in them and the demonstrations, and in general the study and what follows from it. From all of these, scientific knowledge and truth are established. Again, what is summed up from division becomes a definition; for the definition is taken both before division and after: before, when it is conceded or laid down; after, when it is demonstrated. And in perception the universal is summed up from the particular; for perception is the starting point of induction, and the universal is its end. Induction, then, does not show what a thing is, but that it is or is not; division presents what it is; and definition, like division, teaches the substance and what it is, but not whether it is; while demonstration makes clear all three: whether it is, what it is, and why it is. Some definitions also include the cause.

Since we have scientific knowledge when we see the cause, and there are four causes (the matter, the mover, the form, the end), definition will be fourfold. First, then, one must take the genus, in which are the nearest of the higher terms, and after this the proximate differentia. The continuous series of differentiae, cut and divided off, fills out the essence. It is not necessary to state all the differentiae of each thing, but only those that make the species. Geometrical analysis and synthesis resemble dialectical division and definition; and from division we run back to what is simpler and more fundamental. We divide the genus of the thing sought into the species contained in it; for example, in the case of man, we divide “animal,” which is the genus, into the species that appear in it, mortal and immortal; and so, always cutting the genera that seem compound into simpler species, we arrive at what is sought and no longer admits division. For having divided animal into mortal and immortal, and then the mortal into land-dwelling and water-dwelling, and again the land-dwelling into winged and walking, and so dividing the species proximate to what is sought, which also contains what is sought, we shall come by cutting to the simplest species, which contains nothing else but only what is sought. For again we divide the walking into rational and irrational. And then, selecting the species taken from the division that are proximate to man, and putting them together into one account, we give the definition of man, which is: a mortal, land-dwelling, walking, rational animal.

Hence division holds the place of matter for definition, seeking out the simplicity of the name, while definition holds the place of the craftsman and maker, putting together, constructing, and presenting the knowledge of what is. Definitions are neither of the things themselves nor of the Ideas; rather, of the things of which we have universal concepts, we say that definitions are the accounts that express these concepts; for divisions too are made of these concepts. Of divisions, one divides what is divided into species, as a genus; another into parts, as a whole; another into accidents. The division of a whole into parts is conceived for the most part in terms of magnitude; the division into accidents can never be comprehended entire, since every being must certainly have a substance. Hence both these divisions are not approved, and only the cutting of the genus into species is approved, by which both sameness in genus and difference in specific differentiae are marked. The species is always seen in some part, but not conversely: if something is a part of something, it will not therefore also be a species. For the hand is a part of the man, but it is not a species. And the genus is present in the species, for “animal” is in both man and ox; but the whole is not present in the parts, for the man is not in his feet. Therefore the species is more proper than the part. And whatever is predicated of the genus will all be predicated of the species too.

It is best, then, to divide the genus into two species, or if not, into three. The species, when divided more generally, are characterized by the same and the other; and then, when divided through the things signified generically, they are characterized by these. For each of the species is either substance (as when we say, “of beings, some are bodies, others incorporeal”), or quantity, or quality, or relation, or place, or time, or position, or having, or acting, or being acted upon. Whoever has scientific knowledge of anything whatever will also give its definition; so that one who cannot comprehend in an account and define anything whatever could never have scientific knowledge of it. And it is from ignorance of definition that the many disputes and deceptions arise. For if the one who knows the thing has knowledge of it in his mind, and can also make clear in an account what he thinks, and the expression of the thought is a definition, then it is necessary that the one who knows the thing can also give its definition.

The differentia too is added to definitions, holding the place of a sign for the definition. At any rate, when “capable of laughter” is added to the definition of man, it makes the whole: a rational, mortal, land-dwelling, walking animal, capable of laughter. For the things added to the definition by way of differentia are signs of the things proper to it, but do not indicate the nature of the things themselves. Indeed, they say that the differentia is the rendering of a property; and insofar as what has the differentia differs from all others, a differentia that belongs to it alone and is convertible with the thing in definitions, one must necessarily take the first genus as primary and subsisting. In the longer definitions, then, the multitude of species found through the ten categories is taken; in the shortest, the leading ones among the proximate species, taken together, signify the substance and nature of the thing; and the shortest consists of three, the genus and two of the most necessary species. This is done for brevity. We say, then: “Man is the rational animal capable of laughter.” And one must also take in what belongs peculiarly to the thing defined, either its own excellence or its own work, and some other such things. Definition, then, though it explains the substance of a thing, cannot comprehend the nature of the thing exactly, but it makes the substance plain through the most proper species; and definition holds the substance, as it were, in the manner of a quality.

The causes that produce suspension of judgment are, at the highest level, two: one is the changeable and unstable character of human judgment, which by nature produces disagreement, whether of people with one another or of each with himself; the second is the disagreement in things, which reasonably is productive of suspension. For since we were able neither to trust all impressions, because of their conflict, nor to distrust them all, because the one that says all are untrustworthy, being one of them all, is included together with them all, nor to trust some and distrust others, because of their equality, we have been brought to suspension. Of these very chief causes of suspension, the instability of the mind produces disagreement, and disagreement is the proximate cause of suspension. Hence life is full of lawcourts and councils and assemblies, and in general of choosing and avoiding the things called good and bad, which are marks of a mind in perplexity and wavering before the equal force of opposing things. And the book-chests are full of the treatises and works of those who disagree in their doctrines and have persuaded themselves that they know the truth in things.