Aristotle · a new plain-English translation from the original language
1| On Interpretation. First we must settle what a noun is and what a verb is, then what a negation is, and an affirmation, and a statement, and a sentence. Now spoken sounds are symbols of affections in the soul, and written marks are symbols of spoken sounds. And just as written marks are not the same for all men, neither are spoken sounds. But the affections of the soul themselves, of which these are primarily signs, are the same for all; and the things of which these are likenesses are also, already, the same. This has been discussed in the work on the soul, for it belongs to a different inquiry. Now just as in the soul there is at one time a thought without truth or falsity, and at another time a thought to which one of these must already belong, so it is also in speech; for falsity and truth have to do with combination and division. Nouns themselves and verbs by themselves resemble a thought without combination and division — for instance 'man' or 'white,' when nothing further is added; for it is not yet true or false. A sign of this is that even 'goat-stag' signifies something, but not yet anything true or false, unless 'is' or 'is not' is added, either simply or with reference to time.
2| A noun, then, is a spoken sound significant by convention, without time, no part of which is significant in separation. For in 'Callippus' the 'horse'-part signifies nothing by itself, as it does in the phrase 'fine horse.' Yet it is not the same with compound nouns as with simple ones; for in simple nouns the part is in no way significant, while in compound nouns the part is meant to be significant, but not in separation from the rest — for instance in 'pirate-boat' the 'boat'-part signifies nothing by itself. 'By convention' means that no noun is a noun by nature, but only when it becomes a symbol; for even inarticulate noises — for instance those of beasts — make something clear, yet none of them is a noun. Now 'not-man' is not a noun. Nor indeed is there a name laid down for what one should call it, for it is neither a sentence nor a negation. Let it be called an indefinite noun, since it holds alike of anything whatever, whether existing or not existing. Again, 'of Philo' or 'to Philo' and the like are not nouns but inflections of a noun. Its account is the same as that of the noun in other respects; but whereas with 'is' or 'was' or 'will be' added it is not true or false, the noun always is — for instance 'of Philo is' or 'of Philo is not': nothing here is yet either true or false.
3| A verb is what additionally signifies time, no part of which signifies anything by itself, and it is always a sign of things said of something else. I say that it additionally signifies time in this sense: 'health' is a noun, but 'is healthy' is a verb, for it additionally signifies that this holds now. And it is always a sign of what is said of something else — of what holds of a subject, or is in a subject. I do not call 'is not healthy' or 'does not ail' a verb; for though it additionally signifies time and always holds of something, there is no name laid down for this difference — let it be called an indefinite verb, since it holds alike of anything whatever, whether existing or not existing. Likewise 'was healthy' or 'will be healthy' is not a verb but an inflection of a verb; it differs from the verb in that the verb additionally signifies the present time, while the inflections signify the time around it. Verbs said just by themselves are nouns and signify something — for the speaker fixes his thought, and the hearer comes to rest — but they do not yet signify whether a thing is or is not; for not even 'to be' or 'not to be' is a sign of the fact, not even if you say simply 'being' itself, unqualified. For by itself it is nothing, but it additionally signifies some combination, which cannot be thought without the things combined.
4| A sentence is a spoken sound significant by convention, some part of which is significant in separation — as an expression, though not as an affirmation or negation. I mean, for instance, 'man' signifies something, but not that it is or is not; but it will be an affirmation or negation if something is added. But a single syllable of 'man' is not significant.: for in 'mouse,' the '-ouse' is not significant, but is now only a sound. In double words the part does signify, but not in its own right, as said before. Every sentence is significant, not as an instrument, but, as said, by convention. But not every sentence is a statement-making sentence — only one in which truth or falsity is present. It is not present in all: a prayer, for instance, is a sentence, but neither true nor false. Let the others be set aside, for their study belongs more properly to rhetoric or poetics; the statement-making sentence belongs to the present inquiry.
5| The first single statement-making sentence is the affirmation, then the negation; all the others are single by conjunction. Every statement-making sentence must be made of a verb or an inflection of a verb; for even the account of 'man' is not yet a statement-making sentence unless 'is' or 'was' or 'will be' or something of that kind is added. Why 'the two-footed land animal' is one thing and not many is a further question — for it is not simply by being said in close succession that it will be one. But this belongs to another inquiry. A statement-making sentence is single either when it makes clear one thing, or when it is single by conjunction; sentences are plural when they make clear several things and not one, or when they lack conjunction. Let the noun or the verb by itself be called just an expression, since it is not possible to signify something in speech in such a way as to make a statement — whether one is answering a question or speaking on one's own initiative. Of these, the simple statement is one in which something is said of something, or something is said to be absent from something; while the statement composed of these is already a kind of compound sentence. A simple statement is a spoken sound significant about whether something holds or does not hold, in the way the times are divided.
6| An affirmation is a statement of something about something; a negation is a statement of something away from something. Now since it is possible to state as not holding what does hold, and as holding what does not hold, and as holding what does hold, and as not holding what does not hold — and likewise for the times outside the present — it would be possible for anything that has been affirmed to be denied, and for anything that has been denied to be affirmed. So it is clear that to every affirmation there corresponds an opposite negation, and to every negation an opposite affirmation. And let this be called a contradiction: an affirmation and a negation that are opposite. I call opposite the affirmation and negation of the same thing about the same thing — not homonymously — together with whatever other qualifications we make against sophistical objections.
7| Since some things are universal and some particular (I call universal what is by nature predicated of several things, and particular what is not — for instance 'man' is among the universals, and 'Callias' among the particulars), it is necessary to state that something holds or does not hold, sometimes of one of the universals, sometimes of one of the particulars. Now if one makes a universal statement about a universal, affirming or denying that it holds, the statements will be contrary. I mean by making a universal statement about a universal, for instance 'every man is white,' 'no man is white.' But when the statements are about universals, though not made universally, these are not contrary, even though what they signify may sometimes be contrary. I mean by not making a universal statement about universals, for instance 'a man is white,' 'a man is not white'; for though 'man' is universal, the statement does not use it as universal — for 'every' does not signify the universal, but that it is taken universally. But to predicate the universal universally of what is predicated universally is not true; for no affirmation will be true in which the universal is predicated universally of what is predicated universally — for instance, 'every man is every animal.'
8| I call an affirmation opposed to a negation contradictorily when the one signifies the universal and the other signifies the same thing as not universal — for example, every man is white — not every man is white, no man is white — some man is white. And I call an affirmation of the universal opposed to a negation of the universal contrarily, for example every man is white — no man is white, every man is just — no man is just. Hence these latter cannot both be true at the same time, but the ones opposed to them can sometimes both be true of the same subject at the same time, for example not every man is white and some man is white. Now among the contradictions that are universal-of-universals, one of the two must necessarily be true or false, and likewise among those that concern particulars, for example Socrates is white — Socrates is not white; but among those that concern universal terms taken not universally, it is not always the case that one is true and the other false. For it is true at the same time to say that there is a white man and that there is not a white man, and that there is a beautiful man and that there is not a beautiful man. For if a man is ugly, he is also not beautiful; and if something is coming to be, it also is not.
9| It might seem strange at first sight, because "there is not a white man" appears to signify at the same time that no man is white; but in fact it neither signifies the same thing nor does so of necessity. And it is clear too that a single negation belongs to a single affirmation. For the negation must deny the very same thing that the affirmation affirmed, and of the same subject — either of some particular subject or of some universal subject — and it must do so in the same way, either as universal or as not universal. I mean, for example, Socrates is white — Socrates is not white. But if something else is denied, or the same thing denied of something else, that will not be the opposite statement but a different one. To "every man is white" the opposite is "not every man is white"; to "some man is white" the opposite is "no man is white"; to "there is a white man" the opposite is "there is not a white man." It has been stated, then, that to one affirmation one negation is opposed contradictorily, and which these are; and that the contrary statements are different ones, and which these are; and that not every contradiction is true or false, and why, and when it is true or false.
10| An affirmation and a negation are single when they signify one thing of one thing, whether the subject taken universally is taken as universal or not in the same way — for example, every man is white — not every man is white, there is a white man — there is not a white man, no man is white — some man is white, provided that "white" signifies one thing. But if one name is imposed on two things which do not make up one thing, there is not a single affirmation nor a single negation — for example, if someone were to set the name "cloak" on both a horse and a man, then "the cloak is white" would not be a single affirmation nor would its negation be single. For this is no different from saying "the horse and the man are white," and this in turn is no different from saying "the horse is white and the man is white." If, then, these signify many things and are many statements, clearly the first statement too signifies either many things or nothing — for some particular man is not a horse. So in these cases too it is not necessary that of the contradiction one member be true and the other false.
11| In the case, then, of things that exist and have come to be, the affirmation or the negation must be true or false; and in the case of universals taken universally, it is always necessary that one be true and the other false, and likewise in the case of particulars, as has been said; but in the case of universals not taken universally, it is not necessary — and this too has been discussed. But in the case of particulars that are future, it is not the same. For if every affirmation and negation is true or false, then everything must either hold or not hold; so that if one man says something will be and another says this same thing will not be, clearly one of them must be speaking the truth, if every affirmation and negation is true or false — for both cannot hold at once in such cases. For if it is true to say that a thing is white or that it is not white, it must be white or not white; and if it is white or not white, it was true to affirm it or to deny it; and if it does not hold, one is lying, and if one is lying, it does not hold — so that either the affirmation or the negation must be true or false. Nothing, then, either is or comes to be by chance or as it chances, nor will it be or not be so, but everything happens of necessity and not as it chances.
12| For either the one who affirms will be speaking the truth or the one who denies. For otherwise the thing would equally have come to be or not have come to be; for what happens as it chances is no more thus than not thus, either now or in the future. Further, if it is white now, it was true to say beforehand that it would be white, so that it was always true to say of anything that has come to be that it is or will be. But if it was always true to say that it is or will be, it is not possible for this not to be, or not to come to be. And what cannot fail to come to be, it is impossible for it not to come to be; and what it is impossible for not to come to be, it is necessary for it to come to be. Everything that is going to be, then, comes to be of necessity. Nothing, therefore, will happen as it chances or by chance; for if by chance, it is not by necessity. But neither is it possible to say that neither of the two is true — that is, that it neither will be nor will not be. For, in the first place, if the affirmation is false, the negation is not true, and if this in turn is false, it follows that the affirmation is not true either. And besides this, if it is true to say that a thing is white and large, both must hold of it; and if they will hold tomorrow, they will hold tomorrow. But if it is neither going to be nor not going to be tomorrow, then there would be no such thing as what happens as it chances — for example, a sea battle;
13| for it would have to be that a sea battle neither takes place tomorrow nor fails to take place. These, then, and others like them, are the absurdities that follow, if it is necessary, of every affirmation and negation — whether the statements concern universals spoken of universally or concern particulars — that one of the opposed pair be true and the other false, and that nothing that comes to be is as it chances, but everything is and comes to be of necessity. It would follow that there would be no need to deliberate or to take trouble, on the assumption that if we do this, this will result, but if we do not, it will not. For nothing prevents someone from having said ten thousand years ago that this would be so, and another having denied it, so that whichever of the two it was true to say at that time would necessarily come to be. And indeed it makes no difference either whether anyone actually spoke the contradiction or not; for it is clear that the facts are as they are even if one man did not affirm it and another deny it. For it is not on account of its being affirmed or denied that a thing will be or will not be, nor is this any more so for ten thousand years back than for any length of time whatever. Hence if in the whole of time the state of things was such that one or the other of the two was truly assertible, it was necessary for this to come to be, and each thing that has come to be always was such that it came to be of necessity. For what anyone truly said would be, it was not possible for this not to come to be; and of what comes to be, it was always true to say that it would be.
14| If then these consequences are impossible — for we see that there is a starting point of future things both from deliberating and from doing something, and that in general, among things that are not always in actuality, the possible to be and not to be alike is present; things in which both are admissible, both being and not being, and so also coming to be and not coming to be. And many things are plain to us as standing this way — for instance, that this cloak is capable of being cut up, and yet will not be cut up, but will instead wear out first. Likewise it is also capable of not being cut up; for the wearing out first would not have occurred, if not being cut up were not possible. So too with the other comings-to-be, all those spoken of in terms of this kind of capacity. It is plain, then, that not everything is or comes to be of necessity; rather, some things are as chance has it, and neither the affirmation nor the negation is more true than the other, while for other things one alternative holds more, and as a rule, yet it is still possible for the other to come about instead, and for the first not to.
15| That what is, is, when it is, and that what is not, is not, when it is not, is necessary. Yet it is not necessary that everything which is, is of necessity, nor that everything which is not, is not. For it is not the same thing for everything that is to be of necessity when it is, and for it to be of necessity without qualification; and likewise for what is not. The same account holds for the contradiction. It is necessary that a thing either be or not be, and either will be or will not be; but it is not necessary, once you have divided the alternatives, to say which one is necessary. I mean, for example: it is necessary that there will be a sea battle tomorrow or that there will not be one, but it is not necessary that a sea battle take place tomorrow, nor that it not take place — only that it take place or not take place is necessary. So, since statements are true in the same way as the facts are, it is plain that wherever things stand so that the alternatives are open by chance and admit of the contraries as well, the same necessity must hold for the contradiction. This is what happens with things that are not always, or not always not. In their case, one part of the contradiction must be true and the other false — not this one determinately or that one, but whichever it turns out to be — and one is more true, but not already true or false. So it is plain that it is not necessary, of every affirmation and negation of a pair of opposites, that one be true and the other false; for the case is not the same with things that are not but are capable of being or not being as it is with things that are — rather, it is as has been said.
16| Since an affirmation signifies something said of something, and this something is either a name or the nameless, and what is in the affirmation must be one thing said of one thing (the name and the nameless have been discussed earlier; for I do not call 'not-man' a name but an indefinite name, since the indefinite too signifies, in a way, one thing — just as 'does not recover' is not a verb but an indefinite verb), every affirmation and negation will be composed either of a name and a verb or of an indefinite name and a verb. There is no affirmation or negation without a verb; for 'is', 'will be', 'was', 'comes to be', and all such words, are verbs among those already laid down, since they additionally signify time. So the first affirmation and negation will be 'a man is' — 'a man is not', then 'a not-man is' — 'a not-man is not', and again 'every man is' — 'not every man is', 'every not-man is' — 'not every not-man is'. And the same account holds for the tenses outside the present. But when 'is' is predicated as a third element, the oppositions are then spoken of in two ways. I mean, for example, 'a man is just';
17| I say that in that case 'is' is composed as a third element, either a name or a verb, in the affirmation. So because of this there will be four such statements, of which two will stand to the affirmation and negation as the privations do, following the same line, and two will not. I mean that 'is' will be attached either to 'just' or to 'not just', and likewise the negation. So there will be four. We grasp what is meant from the examples set out below. 'A man is just' — the negation of this is 'a man is not just'. 'A not-just man is' — the negation of this is 'a not-just man is not'. For here 'is' and 'is not' will be attached both to 'just' and to 'not just'. These, then, are ordered as stated in the Analytics. And it is the same way if the affirmation is of the universal name, for example 'every man is just'. The negation of this is 'not every man is just'. 'Every man is not-just' — 'not every man is not-just'. Except that these do not admit of being true together in the same way as the diametrically opposed pairs do; though sometimes they do. These two, then, are opposed to each other, and there are two others opposed to 'not-man' taken as a subject with something added to it;
18| 'A not-man is just' — 'a not-man is not just', 'a not-man is not-just' — 'a not-man is not not-just'. There will be no more oppositions than these. These stand apart from the earlier ones, by themselves, using 'not-man' as a name. In cases where 'is' does not fit, as with 'recovers' and 'walks', the same effect is produced by the verbs so placed as if 'is' had been attached; for example, 'every man recovers' — 'not every man recovers', 'every not-man recovers' — 'not every not-man recovers'. For here one must not say 'not every man', but must attach the 'not', the negation, to 'man'. For 'every' does not signify the universal but that the term is taken universally. This is clear from the following: 'a man recovers' — 'a man does not recover', 'a not-man recovers' — 'a not-man does not recover'. These differ from the former by not being universal. So 'every' or 'no one' signifies nothing further than that the name is taken universally, either in the affirmation or in the negation; the rest must be added just as it was.
19| Since the contrary of 'every animal is just' is the statement signifying that no animal is just, it is plain that these two will never be true together, nor of the same subject; but their opposites will be true together at times, for example 'not every animal is just' and 'some animal is just'. And these follow from them: from 'every man is not-just' follows 'no man is just', and from 'some man is just' follows the opposite of that, namely 'not every man is not-just'; for there must be some who are not. It is also plain that in the case of particulars, if it is true, when asked, to deny, it is also true to affirm; for example, 'Is Socrates wise?' 'No.' Then Socrates is not wise. But in the case of universals, the statement made in the same way is not true; rather, the negation is true. For example, 'Is every man wise?' 'No.' Then every man is not wise — but this is false. Rather, 'not every man is wise' is true; and this is the opposite statement, while the other is the contrary.
20| Names and verbs opposed by way of the indefinite, as with "not-man" and "not-just", might seem to be denials without a name and a verb. But they are not; for a denial must always be either true or false, and one who says "not-man" has stated no more truth or falsehood than one who says "man" — indeed less — unless something further is added. "Every not-man is just" signifies the same as none of those other statements, nor does its opposite, "not every not-man is just," signify the same as any of them; but "every not-just thing is not-man" signifies the same as "no just thing is not-man." When the names and verbs are transposed they signify the same thing, as in "a man is white" and "white is a man." For if this were not so, there would be more than one denial of the same affirmation. But it has been shown that there is one denial of one affirmation. For the denial of "a man is white" is "a man is not white"; and of "white is a man," if this is not the same as "a man is white," the denial will be either "white is not a not-man" or "white is not man." But the one is the denial of "white is a not-man," the other of "a man is white," so that there will be two denials of one affirmation. It is clear, then, that when the name and the verb are transposed, the same affirmation and denial results.
21| To affirm or deny one thing of many, or many things of one, is not a single affirmation or denial unless what is signified by the many is itself some one thing. By "one" I do not mean simply that a single name is applied when there is not some one thing arising from those components — man, for instance, is perhaps both animal and two-footed and tame, but a single thing also comes to be out of these; whereas out of white and man and walking there is no one thing. So neither, if one affirms some one thing of these, is it a single affirmation — it is a single utterance but many affirmations — nor, if these are affirmed of one thing, is it single; rather it is likewise many. If, then, the dialectical question is a request for an answer — either of the premise or of one part of a contradictory pair — and the premise is one part of a single contradictory pair, there could not be a single answer to such statements; for neither is the question one, even if it is true. This has been discussed in the Topics. At the same time it is clear that "what is it?" is not a dialectical question either; for the question must allow one to choose whichever part of the contradiction one wishes to state. Instead the questioner must further specify whether man is this or is not this.
22| Since some things are predicated in combination, such that the whole predicate is one thing made of things predicated separately, while others are not, what is the difference? For it is true to say of man both "animal" separately and "two-footed" separately, and these together as one, and also "man" and "white," and these too together as one. But it is not the case that, if "shoemaker" and "good" each hold, then "good shoemaker" holds too. For if, because each is true, the combination of both must also hold, many absurd consequences will follow. For "man" is true of man, and "white" is true of man, so the whole combination would be true too. Again, if "white" holds of that itself, then the whole would be true too, so that it will be "white white man," and this to infinity. And again, "musical white walking"; and these combined repeatedly, to infinity. Further, if Socrates is Socrates and is man, then Socrates is "Socrates man." And if he is man and two-footed, then he is "man man two-footed."
23| It is clear, then, that if one asserts without qualification that combinations occur in every case, many absurd things follow in what one says; how the matter should be laid down, we now state. Of things predicated, and of the subjects of which they happen to be predicated: whichever are said accidentally — either both of the same subject, or one of the other — these will not be one, as when a man is white and musical, but "white" and "musical" are not one; for both are accidents of the same subject. Nor, even if it is true to say "the white is musical," will "the musical white" be some one thing; for "the musical is white" holds accidentally, so "the white musical" will not be some one thing. This is why "shoemaker" is not, without qualification, "good," but "animal" and "two-footed" are; for the latter combination is not accidental. Further, neither do things already contained within the other combine to form something new. This is why "white" is not said repeatedly, nor is man called "man animal" or "man two-footed"; for "animal" and "two-footed" are already contained in man. But it is true to say something both of a particular thing and without qualification, as when a particular man is called man, or a particular white man is called a white man; not always, however, but when one of a pair of opposites is contained in the term added on — a term to which a contradiction attaches — then it is not true but false, as in calling a dead man a man; but when no such thing is contained, it is true.
24| Or rather: when it is contained, it is always not true; when it is not contained, it is not always true — as with "Homer is something," for instance a poet. Is he, then, also without qualification? Or not? For "is" is predicated of Homer accidentally; it is because he is a poet, and not in its own right, that "is" is predicated of Homer. So that in whatever predications there is no contrariety present — if accounts are used in place of names, and the predicate is predicated in its own right and not accidentally — in these cases it will be true to say both "a certain" and "without qualification." But of what is not, because it is an object of opinion, it is not true to say that it is something that is; for the opinion about it is not that it is, but that it is not.
25| Now that these matters have been settled, we must examine how the denials and affirmations of "possible to be" and "not possible to be," "admissible to be" and "not admissible to be" stand in relation to one another, and likewise those concerning the impossible and the necessary; for they involve certain puzzles. For among composite statements, it is those contradictories that are opposed to one another which are arranged by "to be" and "not to be" — for instance, the denial of "a man to be" is "a man not to be," not "a not-man to be"; and the denial of "a white man to be" is "a white man not to be," but not "a not-white man to be." For if the affirmation or the denial held of everything, it would be true to say that a piece of wood is a not-white man. And if this is so, then also in cases where "to be" is not added, whatever is said in place of "to be" will do the same — for instance, the denial of "man walks" will not be "not-man walks," but "man does not walk"; for it makes no difference to say "man walks" or "man is walking." So that if this holds everywhere, then also the denial of "possible to be" will be "possible not to be," and not "not possible to be." But it seems that the same thing can both be and not be;
26| for everything capable of being cut, or of walking, is also capable of not walking and not being cut. The reason is that everything possible in this way is not always in actuality, so that the denial will hold of it too; for what is capable of walking can also not walk, and what is visible can also not be seen. But surely it is impossible for opposite statements to be true of the same thing; therefore "possible not to be" is not the denial of "possible to be." For from this it follows either that the same thing is affirmed and denied at once of the same subject, or that affirmations and denials do not come about by adding "to be" and "not to be." If, then, the former is impossible, the latter must be the one to choose. The denial of "possible to be," then, is "not possible to be." The same account holds also for "admissible to be"; for the denial of this too is "not admissible to be." And likewise for the others, such as the necessary and the impossible. For just as in those earlier cases "to be" and "not to be" were additions, while the underlying things were, in one case the white, in another the man, so here "to be" and "not to be" become, as it were, the underlying thing, while "to be possible" and "to be admissible" are additions that determine it — just as in those other cases "to be" and "not to be" determined the true and the false, so here these additions determine "to be possible" and "to be not possible."
27| The denial of "possible not to be" is not "not possible to be," but "not possible not to be"; and the denial of "possible to be" is not "possible not to be," but "not possible to be." Hence "possible to be" and "possible not to be" might seem to follow from one another; for the same thing can possibly be and not be — these are not contradictories of one another, "possible to be" and "possible not to be." But "possible to be" and "not possible to be" are never true together of the same thing at the same time; for they are opposed. Nor indeed are "possible not to be" and "not possible not to be" ever true together of the same thing. Likewise, the denial of "necessary to be" is not "necessary not to be," but "not necessary to be"; and of "necessary not to be" it is "not necessary not to be." And of "impossible to be" the denial is not "impossible not to be," but "not impossible to be"; and of "impossible not to be" it is "not impossible not to be." And in general, as has been said, one must posit "to be" and "not to be" as the underlying subjects, and treat affirmation and denial as what these produce in relation to being and not being, by
28| combining with them. And one must think that these are the opposed pairs of statements: possible — not possible, contingent — not contingent, impossible — not impossible, necessary — not necessary, true — not true. And the entailments come out logically when the terms are set down this way. For "possible to be" is followed by "contingent to be," and this converts with it, and so do "not impossible to be" and "not necessary to be"; "possible not to be" and "contingent not to be" are followed by "not necessary not to be" and "not impossible not to be"; "not possible to be" and "not contingent to be" are followed by "necessary not to be" and "impossible to be"; and "not possible not to be" and "not contingent not to be" are followed by "necessary to be" and "impossible not to be." Let this be examined from the table, as we lay it out: possible to be — not possible to be contingent to be — not contingent to be not impossible to be — impossible to be not necessary to be — necessary not to be possible not to be — not possible not to be contingent not to be — not contingent not to be not impossible not to be — impossible not to be not necessary not to be — necessary to be
29| Now "impossible" and "not impossible" follow upon "contingent" and "possible," and upon "not contingent" and "not possible," contradictorily, but in reversed order. For "possible to be" is followed by the denial of "impossible" — that is, "not impossible to be" — and the denial "not possible to be" is followed by the affirmation "impossible to be"; for "impossible to be" follows upon "not possible to be." For "impossible to be" is an affirmation, and "not impossible to be" is a denial. How matters stand with "necessary" must now be examined. It is clear that it is not the same here, but the contraries follow one another, while the contradictories go their separate way. For "not necessary to be" is not the denial of "necessary not to be"; for it is possible for both to be true of the same thing at once, since what is necessary not to be is also not necessary to be. The reason why "necessary" does not follow in the same way as the others is that "impossible" is assigned in a manner contrary to "necessary," though it has the same force. For if it is impossible for a thing to be, it is necessary for it not to be, rather than for it to be; and if it is impossible for it not to be, it is necessary for it to be. So that if those terms correspond to "possible" and "not possible" in the same way as before, these correspond in a contrary fashion, since "necessary" and "impossible" do not signify the same thing, but, as has been said, in reversed fashion. Or is it impossible for the contradictories of "necessary" to be set out this way?
30| For what is necessary to be is possible to be; for if it were not, its denial would follow — for it is necessary either to affirm or to deny. So if it is not possible for it to be, it is impossible for it to be; and then it would be impossible for what is necessary to be to be — which is absurd. But then "not impossible to be" follows upon "possible to be," and "not necessary to be" follows upon that; so it turns out that what is necessary to be is not necessary to be — which is absurd. But then again, neither does "necessary to be" follow upon "possible to be," nor does "necessary not to be"; for both can hold of what is possible, and whichever of the two necessity-statements is true, the possibility-statements will no longer both be true. For a thing is possible both to be and not to be at once; but if it is necessary for it to be or not to be, both will no longer be possible. It remains, then, that "not necessary not to be" follows upon "possible to be." For this is true also of what is necessary to be. Indeed this statement is the contradictory of the one that follows upon "not possible to be": for that is followed by "impossible to be" and "necessary not to be," whose denial is "not necessary not to be." So these contradictories too follow in the manner stated, and nothing impossible results when they are set out this way.
31| One might raise the difficulty whether "possible to be" follows upon "necessary to be." For if it does not follow, its contradictory will follow, namely "not possible to be"; and if someone should deny that this is the contradictory, he would have to say "possible not to be" instead — and both of these are false of what is necessary to be. But again, the same thing seems capable of both being cut and not being cut, and of being and not being, so that what is necessary to be would turn out to be contingently not to be — and this is false. It is clear, then, that not everything possible to be, or to walk, is also possible for its opposite; there are cases where this is not true — first of all among things possible not by way of reason, as for instance fire is capable of heating, and has a nonrational capacity. Now capacities that involve reason are the same capacities for several things, including contraries, but the nonrational ones are not all so; rather, as has been said, fire is not capable of both heating and not heating, nor are the other things that are always in activity. Some things, however, even among those with nonrational capacities, can admit contraries at once. But this has been said for the sake of showing that not every capacity is a capacity for opposites, not even all those spoken of as belonging to the same kind.
32| And some capacities are equivocal. For "possible" is not said in a single sense: in one sense a thing is called possible because it is true of it as actually being the case — for instance, a thing is "possible to walk" because it is walking, and in general a thing is "possible to be" because what is called possible to be already actually is; in another sense, a thing is called possible because it could be actual — for instance, a thing is "possible to walk" because it could walk. This latter capacity belongs only to things capable of change, while the former belongs also to unchangeable things. In both cases it is true to say that it is "not impossible" to walk or to be, both of what is already walking and in activity and of what merely has the capacity to walk. Now it is not true to say "possible" in this second sense of what is necessary, without qualification, but the other sense is true of it. So that, since the universal follows upon the particular, what necessarily is is followed by its being possible to be — though not in every sense of "possible." And perhaps the necessary and the not-necessary are indeed the starting point of everything's either being or not being, and the rest must be examined as following upon these. It is clear from what has been said that what necessarily is is in actuality; so that if eternal things are prior, actuality too is prior to potentiality. And some things are actualities without potentiality — the primary substances, for instance — while others exist with potentiality, being prior in nature but posterior in time; and others are never actualities but only potentialities.
33| Is an affirmation contrary to a negation, or is an affirmation contrary to an affirmation — is the statement "every man is just" contrary to the statement "no man is just," or is "every man is just" contrary to "every man is unjust"? For example: "Callias is just" — "Callias is not just" — "Callias is unjust." Which of these is the contrary of the first? If what is in speech follows what is in thought, and there the opinion of the contrary is the contrary opinion — for example, that every man is just is contrary to that every man is unjust — then the same must hold of affirmations in speech as well. But if there the opinion of the contrary is not the contrary opinion, then neither will the affirmation be contrary to the affirmation, but rather the negation we mentioned will be. So we must examine which true opinion is contrary to a false opinion: the one expressed by the negation, or the one that holds the contrary to be so. I mean this: there is a true opinion of the good, that it is good, another that it is not good, which is false, and a third, that it is bad. Which of these is contrary to the true one? And if there is only one, in virtue of which is it the contrary? To suppose that contrary opinions are defined by this — by being opinions of contraries — is false.
34| For the opinion that the good is good and the opinion that the bad is bad may well be the same and true, whether there are several such opinions or only one. Yet these things — good and bad — are contraries. But opinions are not contrary by being opinions of contraries, but rather by being held in a contrary way. Now if there is an opinion of the good that it is good, and another that it is not good, and there is also something else which does not belong to it and cannot belong to it, then none of the other opinions should be posited — neither those that hold what does not belong to belong, nor those that hold what does belong not to belong (for both kinds are unlimited in number: both those that opine that what does not belong belongs, and those that opine that what belongs does not belong) — but only those in which the deception properly lies. And these are the ones from which comings-to-be arise. Comings-to-be are from opposites, so the deceptions are too. If, then, the good is both good and not bad, and one of these belongs to it in its own right and the other accidentally (for it is accidental to it to be not bad), and the opinion that grasps a thing in its own right is more true of each thing than the other, and likewise more false, if indeed it is also more true — then the opinion that the good is not good is false of what belongs to it in its own right, while the opinion that it is bad is false of what belongs to it accidentally.
35| So the negative opinion about the good would be more false than the opinion holding the contrary. But the one who holds the contrary opinion is the one most deceived about each thing, for contraries are among the things that differ most from one another concerning the same subject. If, then, one of these opinions is the contrary of the true one, but the opinion of the contradiction is more contrary still, it is clear that this latter would be the contrary one. The opinion that the good is bad is a composite opinion; for the same person must also, probably, suppose that it is not good. Further, if the same must hold in other cases too, then on this ground as well the account would seem to be well stated; for either the rule of contradiction holds everywhere, or nowhere. In cases where a thing has no contrary, the opinion opposed to the true one is false — for instance, one who thinks that a man is not a man is deceived. If, then, these opinions are contraries, so too are the other pairs that stand as contradictions. Further, the opinion of the good, that it is good, stands in the same relation as the opinion of the not-good, that it is not good, and besides these there is the opinion of the good, that it is not good, and the opinion of the not-good, that it is good. What, then, would be the contrary of the true opinion of the not-good, that it is not good?
36| It is surely not the opinion saying that it is bad; for then at some point both could be true at once, and a true opinion is never contrary to a true opinion — for something not good may be bad, so that it is possible for both to be true together. Nor again is it the opinion that it is not bad, for this too is true; for in that case as well both could hold together. What remains, then, is that the opinion of the not-good, that it is good, is contrary to the opinion of the not-good, that it is not good — for this is false. So too the opinion of the good, that it is not good, is contrary to the opinion of the good, that it is good. It is clear that it will make no difference even if we take the affirmation universally; for the universal negation will be the contrary — for instance, to the opinion holding that whatever is good is good, the contrary is the opinion that none of the good things is good. For the opinion of the good, that it is good, if the good is taken universally, is the same as the opinion holding of whatever is good that it is good; and this differs in no way from holding that everything that is good is good. And likewise for the not-good. So if this is how it stands with opinion, and affirmations and negations in speech are symbols of what is in the soul, it is clear that the negation about the same subject taken universally is contrary to the affirmation — for instance, to "every good thing is good" or "every man is good," the contrary is "nothing is good" or "no one is good," while the contradictory is "not every" or "not everyone."
37| It is clear too that a true opinion cannot be contrary to a true opinion, whether as opinion or as negation. For contrary opinions concern opposites, and concerning these it is possible for the same person to hold the truth; but it is not possible for contraries to belong to the same thing at the same time.