Topics (Aristotle)/Book 1
The purpose of this treatise is to discover a method by which we shall be able to syllogize about every proposed problem from probabilities, and when we ourselves sustain the argument we may assert nothing repugnant. First, then, we must declare what a syllogism is and what are its differences, in order that the dialectic syllogism may be apprehended, for we investigate this in the proposed treatise.
A syllogism then is a discourse in which, certain things being laid down, something different from the posita happens from necessity through the things laid down. Demonstration indeed is when a syllogism consists of things true and primary, or of such a kind as assume the principle of the knowledge concerning them through certain things primary and true; but the dialectic syllogism is that which is collected from probabilities. Things true and primary indeed are those which obtain belief, not through others, but through themselves, as there is no necessity to investigate the "why" in scientific principles, but each principle itself ought to be credible by itself. Probabilities however are those which appear to all, or to most men, or to the wise, and to these either to all or to the greater number, or to such as are especially renowned and illustrious. Moreover a contentious syllogism is one which is constructed from apparent, but not real probabilities, and which appears to consist of probabilities, or of apparent probabilities. For not every thing which appears probable is so, since none of those which are called probable has entirely the superficial image (of probability), as happens to be the case about the principles of contentious arguments, since immediately, and for the most part, the nature of the false in them is evident even to those who have small perception. Let then the first of the syllogisms called contentious, be also called a syllogism, but let the other be a contentious syllogism, yet not a syllogism (simply), since it appears indeed to draw an inference, but does not collect one.
Besides all the above-named syllogisms, there are paralogisms, which consist of things peculiar to certain sciences, as happens to be the case in geometry, and those (sciences) allied to it. For this mode seems to differ from the syllogisms enumerated, since he who describes falsely, neither syllogizes from the true and primary, nor from the probable, for he does not fall into definition, since he neither assumes things which appear to all men, nor those which appear to the greater number, nor to the wise, and to these neither to all, nor to the greater part, nor to the most famous; but he makes a syllogism from assumptions, appropriate indeed to science, yet not from the true, as either by describing semicircles not as they ought to be, or by drawing certain lines not as they ought to be drawn, he produces a paralogism.
Let then the species of syllogisms, to comprehend them summarily, be those which I have stated, and in a word, to sum up all that have been spoken of, and those which shall be mentioned hereafter, let our definition be so far given, because we do not propose to deliver an accurate description of any of these, but wish merely to run through them briefly, thinking it quite sufficient according to the proposed method, in some way or other to be able to know each of them.
It will be consequent upon what we have stated to describe to what an extent and for what subjects this treatise is useful. It is so for three: exercise, conversation, philosophical science. That it is useful for exercise, appears evident from these, that possessing method, we shall be able more easily to argue upon every proposed subject. But for conversation (it is useful), because having enumerated the opinions of the many, we shall converse with them, not from foreign, but from appropriate dogmas, confuting whatever they appear to us to have erroneously stated. Again, (it is useful) for philosophical science, because being able to dispute on both sides, we shall more easily perceive in each the true and the false; also, (it is applicable) to the first principles of each science, since we cannot say any thing about these from the appropriate principles of a proposed science, as they are the first principles of all, but we must necessarily discuss these through probabilities in the singulars. This however is peculiar, or especially appropriate to dialectic, for being investigative, it possesses the way to the principles of all methods.
We shall possess this method perfectly when we are similarly disposed, as in rhetoric, medicine, and such like powers; and this is to effect what we choose from possibilities, since neither will the rhetorician persuade from every mode, nor the physician heal, but if a man omits no possibility we say that he sufficiently possesses science.
First then let us examine of what this method consists. If therefore we assume for how many, what kind of, and from what things, arguments are constructed, and how we may be well provided with these, we shall sufficiently gain our point. Now those things are equal and the same in number from which arguments are constructed, and about which syllogisms are conversant; for arguments are constructed of propositions, but the things with which syllogisms are conversant are problems. Now every proposition and every problem shows either genus, property, or accident; for difference, being generic, we must place together with genus. Since however of property, one kind signifies the very nature of a thing, but the other does not signify it, let property be divided into the two above-named parts, and let what signifies the very nature of a thing be called definition, but let the other, according to the common appellation attributed about these, be called property. Now it is clear from what we have said, that according to the present division it happens that all are four, either property, or definition, or genus, or accident. Let however no one suppose that we say that each of these asserted by itself is a proposition or a problem, but that problems and propositions are produced from these. Still a problem and a proposition differ in mode, since when it is thus said, is a pedestrian biped animal the definition of man? and is animal the genus of man? there is a proposition, but if (it should be said), whether is a pedestrian biped animal the definition of man or not? there is a problem. So also in other things. Wherefore with propriety problems and propositions are equal in number, for from every proposition you will make a problem by changing the mode.
We must describe what definition, property, genus, and accident are. Now definition is a sentence signifying what a thing is: and either a sentence is employed instead of a noun, or a sentence instead of a sentence, since it is possible to define some things which are signified by a sentence. As many however as in some way or other make the explanation by a noun, evidently do not explain the definition of the thing, since every definition is a certain sentence. Still we must refer a thing of this kind to definition, as that the becoming is beautiful; in like manner also whether sense and science are the same or different, since about these definitions, whether they are the same or different, there is a very great discussion. In short, however, all things may be called definitive which are under the same method with definitions, but that all which have been spoken of are of this kind is evident from these (considerations). For when we are able to argue that a thing is the same and that it is different, we shall by the same manner be well supplied with arguments about definitions, since when we have shown that it is not the same we shall have upset the definition. Still what is now said is not converted, since it is not enough to construct a definition to show that it is the same, but for the subversion of definition it is sufficient to show that it is not the same thing.
Property, indeed, is that which does not show what a thing is, but is present to it alone, and reciprocates with the thing. As it is the property of a man to be capable of grammar, for if he is a man he is capable of grammar, and if he is capable of grammar he is a man; since no one calls property that which may possibly be present with something else, as sleep to a man, not even if it should happen at a certain time to be present with him alone. If then any thing of this kind should be called property, it will not be called property simply, but at a certain time or with reference to something, since to be on the right hand is sometimes a property, but biped happens to be called property with reference to something, as to man with reference to horse and dog; but that nothing which may possibly be present with something else is reciprocally predicated is clear, since it is not necessary if any thing sleeps that it should be a man.
Genus, however, is that which is predicated of many things differing in species, in (answer to) what a thing is; but let those things be said to be predicated in (answer to) what a thing is, which are fitted to answer the person inquiring what the proposed thing is, as it is adapted to man, when it is asked what the proposed thing is, to say that he is animal. Moreover it is generic, whether one thing is in the same genus with another or in a different genus, since such a thing falls under the same method with genus, as having discussed that animal is the genus of man, and in like manner of ox, we shall reason that they are in the same genus; if, however, we should show that it is the genus of one of them, but not of the other, we shall reason that these are not in the same genus.
Accident, again, is that which is not any of these, neither definition, nor property, nor genus; yet it is present with a thing, and is that which may possibly be present with some one and the same thing and may not be present, as, to sit may be and may not be present with some one and the same thing, and in like manner whiteness, for there is nothing to prevent the same thing being at one time white and at another not white. Now of these definitions of accident, the second is the better; since when the first is stated, it is necessary in order to understand it, to know previously what definition genus and property are, but the second is self-sufficient for the knowledge per se of what the thing asserted is. To accident also let comparisons of things with each other belong, in whatever way they are derived from accident, as, whether the honourable or the advantageous be preferable, and whether a life of virtue or of enjoyment is the sweeter, and if there happens to be any other assertion similar to these, for in all things of this kind, the question arises as to which the predicate rather happens to belong. Still from these it is manifest that there is nothing to prevent accident sometimes, and with reference to something, becoming property, as to sit being accident, when some one alone sits, will then be a property, but one not sitting alone, it will be a property with reference to those who do not sit, so that nothing prevents accident from becoming property in a certain relation and at a certain time; simply, however, it will not be property.
Nevertheless we must not forget that every thing which is referred to property, genus, and accident will also be adapted to definitions, for by showing that a thing is not present with that alone which is under definition, as in the case of property, or that what is given in the definition is not genus, or that some one of those things stated in the definition is not present, which may also be said in accident, we shall have subverted the definition; so that, on account of the reason given before, all those things which have been enumerated will after a certain manner be definitive. Nevertheless we must not on this account look for one method universal in all things, as neither is it easy to discover this, and if it were discovered it would be altogether obscure and useless to the proposed treatise. But a peculiar method being delivered as to each of the defined genera singly, the discussion of the proposition will be easy from those things which are appropriate to each. Wherefore, as we have before said, we must make a rough division, but of the rest we must join those which are especially appropriate to each, denominating them both definitive and generic. What, however, have been set forth have almost been adapted to each.
We must first of all distinguish about "the same," in how many ways it is predicated; but "the same," to speak in general terms, may appear to be divided triply, since we are accustomed to denominate a thing the same, in number, or in species, or in genus; in number indeed when the names are many but the thing one, as a garment and a vestment, but in species when the things being many are without specific difference, as man with man, and horse with horse, for such things are said to be the same in species as are under the same species: in like manner also, those are the same in genus which are under the same genus, as horse with man. Nevertheless, it may seem indeed that water from the same fountain, being called the same, has a certain difference besides the modes enumerated, yet such a thing must be placed at least in the same arrangement with those, which are in some way or other said to be under one species, for all such things appear to be of a kindred nature and similar to each other, since all water is said to be the same in species with all water, because of the possession of a certain similarity; but water from the same fountain differs in nothing else except that the similarity is greater; wherefore we do not separate it from those which some way or other are said to be according to one species. Confessedly, however, that which is one in number, seems especially to be called the same, by all men; still we usually attribute this in many ways, most properly indeed and chiefly, when "same" is attributed in name or definition, as garment to a vestment, and animal pedestrian biped, to man; secondly, when (it is attributed) in property, as what is susceptible of science to man, and what naturally is carried upwards, to fire; thirdly, when from accident, as that which sits or is musical, to Socrates. For all these would signify one thing in number, and that what we have now said is true, a person may especially learn, from those who change appellations; for frequently when we desire to call some one who is sitting, by name, we change (the appellation), when he to whom we give the order, does not happen to understand, as if he would rather understand from accidents, and we desire him to call to us, the person who is sitting or discoursing, evidently considering it the same thing to signify by name and by accident. Let therefore "same" be triply divided, as we have said.
That disputations are composed from the things mentioned before, and through these, and pertain to these, we have the first evidence through induction, since if any one considers each of the propositions and problems, it will appear to have originated either from definition, or from property, or from genus, or from accident. Another evidence however is by syllogism, for it is necessary that every thing which is predicated of a certain thing, should either reciprocate with that thing or not. And if indeed it reciprocates it will be definition or property, since if it signifies what a thing is, it is definition, but if it does not signify it, it is property, for this was property, viz. that which reciprocates indeed, but does not signify what a thing is. If however it does not reciprocate with the thing, it either is one of those which are predicated in the definition of the subject, or it is not, and if it is one of those predicated in the definition it would be genus or difference, since definition consists of genus and differences, but if it is not of those predicated in definition, it would be evidently accident, for that was said to be accident which is neither definition, nor genus, nor property, yet is present with a thing.
We must next define the genera of the Categories, in which the above-named four (differences) are inherent. Now these are ten in number; what a thing is, quantity, quality, relation, where, when, position, possession, action, passion, for accident, and genus, and property, and definition will always be in one of these categories, since all propositions through these signify either what a thing is, or quality, or quantity, or some other category. Moreover, it is evident from these that he who signifies what a thing is, at one time signifies substance, at another quality, and at another some other category. For when man being proposed, he says that the thing proposed is man or animal, he says what it is, and signifies substance; but when white colour being proposed, he says that the thing proposed is white or colour, he says what it is, and signifies quality. So also, if when the magnitude of one cubit is proposed, he says that what is proposed is a cubit in size, he will say what it is, and will signify quantity, and so of the rest, for each of these, both if it be itself predicated of itself, and if genus (be predicated) of it, signifies what a thing is. When however (it is spoken) of another thing, it does not signify what it is, but quantity or quality, or some other category, so that the things about which and from which arguments (subsist), are these and so many; but how we shall take them, and by what we shall be well provided with them, we must declare hereafter.
In the first place then, let us define what is a dialectic proposition, and what a dialectic problem, for we must not suppose every proposition nor every problem as dialectic, since no one in his senses would propose that which is assented to by no one, nor would he advance as a question what was palpable to all, or to most men, for the latter does not admit of a doubt, but the former no one would admit. Indeed a dialectic proposition is an interrogation, probable either to all, or to the most, or to the wise; and to these, either to all or most, or to the most celebrated, it is not paradoxical, as any one may admit what is assented to by the wise, if it be not contrary to the opinions of the multitude. Dialectic propositions however are both those which resemble the probable and which are contrary to those which appear probable, being proposed through contradiction, and whatever opinions are according to the discovered arts. For if it be probable that there is the same science of contraries, it would also appear probable that the sense of contraries is the same, and if the grammatical art be one in number, that there is one art also of playing on the pipe, but if there are many grammatical arts, there will also be many piping arts, for all these things seem to be similar and akin. So also those things which are contrary to probabilities, being proposed according to contradiction, will appear probable, for if it is probable that we ought to benefit friends, it is also probable that we ought not to injure them. Nevertheless, that we ought to injure friends is contrary, but that we ought not to injure them is contradictory; so also if we ought to benefit friends, we ought not to benefit enemies; but this also is according to the contradiction of contraries, since the contrary is that we ought to benefit enemies, and in like manner in the case of other things. Still the probable will appear in comparison to be the contrary about the contrary, as, if we ought to benefit friends, we ought also to injure enemies. To benefit friends however may appear contrary to injuring enemies, yet whether it is truly so or not, will be shown in what we say about contraries. Notwithstanding, it is apparent that whatever opinions also are according to the arts, are dialectic propositions; since any one would admit those things, which are assented to by persons conversant with such subjects, as in matters of medicine, that the physician (is to be assented to), the geometrician in geometrical concerns, and similarly of others.
The dialectic problem is a theorem tending either to choice and avoidance, or to truth and knowledge, either per se or as co-operative with something else of this kind, about which the multitude either hold an opinion in neither way, or in a way contrary to the wise, or the wise to the multitude, or each of these to themselves. Now some problems it is useful to know, for the purpose of choice or avoidance, as whether pleasure is eligible or not, but others for knowledge only, as whether the world is everlasting or not, some again by themselves, for neither of these purposes, yet do they co-operate to something of this kind, since there are many things which we do not desire to know for themselves, but for the sake of others, in order that through these we may know something else. Moreover, those are problems also, of which there are contrary syllogisms (for they admit a doubt, whether they are so and so, because of there being credible arguments in both respects). And those about which we have no argument from their being vast, conceiving it difficult to assign their cause, e. g. whether the world is everlasting or not, for any one may investigate such things as these.
Let then problems and propositions be distinguished as we have said: a thesis, on the other hand, is a paradoxical judgment of some one celebrated in philosophy, as that contradiction is impossible, as Antisthenes said, or that all things are moved, according to Heraclitus, or that being is one, as Melissus asserted, for to notice any casual person setting forth contrarieties to (common) opinions is silly. Or (a thesis is an opinion) of things concerning which we have a reason contrary to opinions, as that not every thing which is, is either generated or perpetual, as the sophists declare, since (they say) that a musician is a grammarian, though he is neither generated nor eternal, for this, even if it be not admitted by any one, may appear to be from possessing a reason.
A thesis then is also a problem, yet not every problem is a thesis, since some problems are of such a kind, as that we form an opinion about them in neither way; but that a thesis is also a problem is evident, as it is necesary from what we have said, either that the multitude should be at variance with the wise about the thesis, or one or other of these with themselves, since a thesis is a certain paradoxical judgment. Now almost all dialectical problems are called theses, let it, however, make no difference how they are called, as we have not thus divided them from a desire to fabricate names, but that we may not be ignorant what are their real differences.
Still we need not consider every problem nor every thesis, but that which any one may be in doubt about, who is in want of argument and not of punishment or sense, for those who doubt whether we ought to worship the gods and to love our parents or not, require punishment, but those (who doubt) whether snow is white or not, (need) sense. Nor (need we discuss those things) of which the demonstration is at hand, nor those of which it is very remote, for the one do not admit of doubt, but the other, of greater (doubt) than accords to (dialectic) exercise.
These things then being determined, we must distinguish how many species of dialectic arguments there are. Now one is induction, but the other syllogism, and what indeed syllogism is, has been declared before, but induction is a progression from singulars to universals, as if the pilot skilled in his art is the best, so also is the charioteer, and generally the skilful is the most excellent about each thing. Nevertheless, induction is more calculated to persuade, is clearer, and according to sense more known, and common to many things; but syllogism is more cogent, and efficacious against opponents in disputation.
Let then the genera about which, and from which, arguments subsist be defined, as we have stated before, but the instruments by which we shall be well provided with syllogisms are four; one to assume propositions, the second to be able to distinguish in how many ways each thing is predicated, the third to discover differences, and the fourth the consideration of the similar. In a certain way indeed there are three propositions of these, since it is possible to make a proposition as to each of them, as that the beautiful, or the sweet, or the profitable is eligible, and that sense differs from science, in that he who loses the latter may regain it; but this is impossible with the other, and that the wholesome has the same relation to health as what produces good constitutional habit, to a good habit of constitution. Now the first proposition is derived from that which is predicated in many ways, but the second from differences, and the third from similars.
Propositions then must be selected in as many ways as there has been definition about proposition, either choosing the opinions of all, or those of most, or those of the wise, and of these either of all, or of most, or of the most celebrated, or opinions contrary to the apparent, and whatever are according to arts. Yet it is necessary to propose according to contradiction those which are contrary to the apparently probable, as we observed before; but it is useful to produce them by selecting, not only those which are probable, but those also which are like these, as that there is the same sense of contraries, (for there is the same science,) and that we see by admitting, not by emitting, somewhat, as it is thus also with the other senses, since we both hear from admission and not from emission of something, and also taste, and similarly with the rest. Again, whatever are seen in all or in most things, we must take as principle and apparent theses, since persons lay down these who do not see, at the same time, in what thing it does not happen so. We must also select from written arguments, but descriptions must be made supposing separately about each genus; as about good or about animal, and about every good, beginning from what it is; we must also note besides, the several opinions, as that Empedocles said there are four elements of bodies, for any one would admit what had been asserted by some celebrated man.
But to speak comprehensively, there are three parts of propositions and of problems; for some propositions are ethical, others physical, but others logical. The ethical then are such, as whether it is right to obey parents rather than the laws, if the two are discordant; the logical, as whether there is the same science of contraries or not; and the physical, whether the world is perpetual or not; the like also occurs in problems. Still it is not easy to explain by definition, what the quality of each of the above-named is, but we must endeavour to know each of them from habit, which arises from induction, addressing our attention, according to the before-mentioned examples.
With regard then to philosophy, we must discuss these according to truth; but as to opinion, dialectically; still we must assume all the propositions as universal as possible, and make many one, as that there is the same science of opposites, afterwards that there is of contraries, and also of relatives. In the same manner we must divide these again, as long as it is possible to divide them, as that (there is the same science) of good and of evil, and of white and black, of the cold and the hot, and likewise of other things.
Concerning proposition then, what has been stated will suffice, but as to how many ways (a thing may be predicated), we must discuss not only such things as are predicated in a different manner, but also we must endeavour to give their reasons; as not only that justice and fortitude are called good in one way, but what conduces to a good habit of body and to health in another way, but also that some things (are called so) from being certain qualities, but others from being effective of something, and not from themselves being certain qualities, and indeed in a similar manner in other things.
Whether however a thing is predicated multifariously, or in one way in species, we must investigate through these. First, we must consider in the contrary, if it is multifariously predicated, whether it differs in species or in name, for some things immediately differ even in names, as the grave is contrary in voice to the sharp, but in magnitude the obtuse. Therefore it is clear that the contrary to the sharp is predicated multifariously, but if this be so, the sharp also is, for according to each of these, the contrary will be different, since the same sharp will not be contrary to the obtuse and to the grave, but the sharp will be contrary to each. Again, to the heavy in voice, the sharp is contrary, but in weight, the light, so that the heavy is predicated multifariously since the contrary also is. Likewise to the beautiful in an animal, the ugly, but in a family, the depraved (is contrary), so that the beautiful is equivocal.
In some, indeed, there is no dissonance in the names, but the difference in them is at once palpable in species, as in white and black, for voice is said to be clear and obscure in the same manner as colour. In these, then, there is no dissonance in names, but their difference is at once evident in species, for colour and voice are not similarly called clear, and this is also evident from sense, for of things which are the same in species, the sense is the same; but we do not judge the lightness which is in voice, and that which is in colour, by the same sense, but one by sight, and the other, by hearing. So also the sharp and the obtuse in fluids and magnitudes, the one indeed by touch, the other by taste, since neither are these dissonant in names, neither in themselves nor in the contraries, for what is obtuse is contrary to each.
Again, we must consider if there is any thing contrary to the one, but nothing simply to the other; as, to the pleasure from drinking, the pain from thirst is contrary; but to that which arises from contemplating, that the diameter of a square is incommensurable with its side, there is nothing (contrary), wherefore pleasure is predicated multifariously. To hate, also, is contrary to the love which is mental, but nothing to that which subsists according to bodily energy, wherefore it is evident that to love, is equivocal. Besides, we must consider the media, if there is a certain medium of some, but not of others, or whether there is of both, yet not the same, as of white and black, in colour, the dark brown; but in voice, there is no medium, unless it be the hoarse, as some say that a hoarse voice is the medium; so that white is equivocal, and black in like manner; yet more, whether there are many media of some things, but one of others, as in the case of white and black; for in colours, there are many media, but in voice, one, viz. the hoarse.
Again, in that which is contradictorily opposed, we must consider if it is predicated multifariously, for if this is multifariously predicated, the opposite to this also will be enunciated multifariously; thus, not to see, is predicated in many ways; in one, not to have sight; in another, not to energize with the sight. Now if this is multifariously, to see, must necessarily be multifariously predicated; for to each (signification of the verb) not to see, there will be something opposed, thus to the not possessing sight, the possession of it, and to the not energizing with the sight, the energizing with it.
Further, we must remark this, in the case of those things, which are predicated according to privation and habit; for if the one, is multifariously predicated, the other is, also; thus, if to perceive, is predicated multifariously, both according to the soul and according to the body, to be deprived of sense, will be multifariously predicated, i. e. both according to the soul and the body. Nevertheless, that the particulars now mentioned, are opposed according to privation and habit, is evident, since animals are naturally adapted to possess each of the senses, viz. both according to the soul and according to the body.
We must look also to the cases, for if "justly" is predicated multifariously, "the just" also, will be multifariously predicated; for the just subsists according to each of those which are justly, thus if justly is predicated, both of judging according to one's own opinions, and also in a proper manner, the just is similarly. Likewise, if the healthy is multifariously, the healthily also, will be spoken multifariously, as if that is called "healthy," which produces, preserves, and signifies health, the "healthily" also, will be predicated either productively, or preservingly, or significantly. And in like manner in other things, when (the noun) itself is multifariously predicated, the case also derived from it, will be spoken in many ways, and if the case (the noun) itself besides.
We must regard too, the genera of the categories, as to name, whether they are the same in all things, since if they are not the same, it is evident that what is predicated, is equivocal; thus good in food is what produces pleasure, in medicine, what produces health, in the soul, to be of a certain quality, as temperate, or brave, or just, similarly also in the case of man. Sometimes indeed it is "the when," as the good in opportunity, for that is called good, which is in season: frequently also quantity, for instance, the moderate, for the moderate also is called good, so that good is equivocal. Likewise clearness in respect of body, is colour, but in voice, that which may easily be heard, and in like manner the acute, for the same, is not predicated in all things, after the same manner, for a rapid voice is called acute, as musicians say, who are conversant with numbers; but an angle is acute, which is less than a right angle, and a sword is acute, which has a sharp point.
We must also notice the genera, of those things which are under the same name, whether they are different and not subaltern, thus ὄνος is both an animal and a vessel, since the definition of them according to the name, is different, for the one will be said to be a certain kind of animal, but the other a certain kind of vessel. If however the genera are subaltern, the definitions need not be different, as of a crow, both animal and bird are the genus, when therefore we say, that a crow is a bird, we also say, that it is a certain kind of animal, so that both genera are predicated of it; likewise also when we say that a crow is a winged biped animal, we say that it is a bird, and thus then both the genera are predicated of the crow, and also the definition of them. This nevertheless does not occur in genera which are not subaltern, since neither when we speak of a vessel, do (we speak of) an animal, nor when (we speak of) an animal, (do we mean) a vessel.
Not only indeed must we observe whether the genera of the thing proposed, be different and not subaltern, but also in regard to the contrary, since if the contrary is predicated in several ways, it is evident that the proposition will be so too.
It is useful also, to regard the definition produced from the composite, as of a white body and white (i. e. clear) voice; for the property being taken away, it is necessary that the same definition should be left. Now this does not occur in equivocals, for instance, in the things now spoken of, for the one, will be body having such a colour, but the other, will be an audible voice; body, then, and voice being taken away, what remains is not the same in each, at least it would be necessary if white, were synonymous, that what is predicated in each (definition), should be (the same).
Frequently also in the definitions themselves, the equivocal, which is consequent, escapes us, wherefore, we must look to the definitions. Thus, if any one were to say, that what is significant and productive of health, is that which is symmetrically disposed with respect to health, we must not leave off, but consider what he calls symmetrically, in each, as if the one, were to be of such a kind, as to produce health, but the other, such as to signify, what is the quality of the habit.
Moreover, (we are to examine) whether they may not be compared according to the more, or similarly, as a light voice, and a light garment, and a sharp flavour, and a sharp voice, for these are neither called light nor sharp similarly, nor one, more than the other. So that the light, and the sharp, are equivocal, for every synonym is capable of comparison, since it will either be predicated similarly, or one more than the other.
Since however of things heterogeneous and not subaltern, the differences are also different in species, as of animal and science, (for the differences of these are diverse,) consider whether those things, which are under the same name, are the differences of different, and not of subaltern genera, as the acute (is the difference) of voice and magnitude, for voice, differs from voice, in acuteness, likewise also one mass, from another, so that the acute is equivocal, for these are the differences of diverse, and not of subaltern, genera.
Again, (observe) whether of things under the same name, there be divers differences, as of the chroma which belongs to bodies, and of that which is in melodies, for of that which belongs to bodies, the differences are, that which diffuses, and that which condenses, the vision, but these are not the same differences of that which is in melodies, so that chroma is an equivocal word, for there are the same differences of the same things.
Once more, since species is not the difference of any thing, notice of those which are under the same name, whether one is species, but the other, difference, as bodily clearness is a species of colour, but vocal (clearness) is a difference, since voice differs from voice, in being clear.
Concerning therefore what is multifariously predicated, we must consider it through these and such as these; but the differences we must investigate in the genera themselves with respect to each other, as what difference there is between justice and fortitude, prudence and temperance, (for all these are from the same genus, virtue,) and of those which do not differ very much, one from the other, as in what, sense, differs from, science, since in things which are very different, the differences are altogether palpable.
We must consider similitude in the case of things of different genera, (thus) as one thing is to another, so is another to another, for instance, as science to the object of science, so is sense to the object of sense, and as one thing in a certain other thing, so is another thing in another, e. g. as sight in the eye, so is intellect in the soul, and as tranquillity in the sea, so is serenity in the air. But most of all, it is necessary to be practised, in things vastly diverse, for we may easily perceive similitudes in the rest. Besides, we must also consider those things which are in the same genus, whether something identical is present with all, as for instance, with man, and horse, and dog; since so far as something identical is present with them, so far are they similar.
To have considered in how many ways a thing may predicated, is useful for perspicuity, (as any one can better know what he admits, when it is clearly explained in how many ways it may be predicated,) and for the construction of syllogisms against the thing itself, and not (merely) against the name. For when it is dubious in how many ways it is predicated, he who answers, and he who questions, may possibly not direct their attention, to the same thing, but when it is explained in how many ways it is predicated and with what object a person admits it, the questioner would appear ridiculous if he did not frame his argument against this. But it is also useful that we may not be deceived (ourselves) by paralogism, and may deceive another by it, since when we know in how many ways predication occurs, we can never be deceived by paralogism, but we shall know if the questioner does not argue against the same thing, and we ourselves, when questioning, shall be able to deceive by paralogism, except the respondent happens to know, in how many ways predication occurs. Nevertheless, this is not possible in all cases, but when of things multifariously predicated, some are true, but others false; this mode however is not appropriate to dialectic, wherefore a thing of this kind, must be altogether avoided by dialecticians, viz. arguing against a name, unless any one should be otherwise incapable of discussing the proposition.
Notwithstanding, it is useful to discover differences, in order to (construct) syllogisms of the same, and of the different, and also to the knowledge of what each thing is. That it is useful for syllogisms about the same, and the different, is clear; for when we have discovered the difference of the things proposed, of whatever kind it may be, we shall have shown that they are not the same, (and it is useful) for the knowledge of what a thing is, because we are accustomed to separate the proper definition of the essence of each thing, by the peculiar differences of each.
On the other hand, speculation upon the similar, is useful for inductive reasons, and for hypothetical syllogisms, and for the statement of definitions. For inductive reasons then, because by the induction of similar particulars, we deem it proper to infer the universal, since it is not easy to form induction, when we are ignorant of similars. (It is useful also) for hypothetical syllogisms, because it is probable that as a thing subsists in one of those which are similar, so also it does in the rest, so that in order that we may discuss any of them sufficiently, we should previously acknowledge, that as a thing is in these, so also is its condition in the subject proposed; but when we have demonstrated that, we shall also have proved the proposition by hypothesis, for we have framed a demonstration, upon the supposition that as a thing is in these, so it is also, in the case of what is proposed. Again, for the statement of definitions (it is useful), since being able to comprehend what in each thing is identical, we shall not be in doubt as to what genus the thing proposed ought to be referred, in definition; for of those which are common, what is especially predicated in (the question) what a thing is, will be the genus; in like manner in those which are vastly different from each other, the contemplation of the similar is useful for definitions, as that tranquillity in the sea, is the same thing as serenity in the air, (for each of them is quiet,) and that a point in a line (is identical) with unity in number, for each is a principle. Wherefore by assigning the common genus in all things, we shall appear not to define in a manner foreign (from the subject), and indeed almost those who define, are accustomed thus to explain, for they say that unity is the principle of number, and that a point is the principle of a line; it is evident then that they refer the genus of both to what is common.
The instruments therefore by which syllogisms are constructed, are these; but the places, for which what we have said, is useful, are those (which follow).