Lastly, we must repeat against these reasoners the argument urged just now. We must explain to them, that there exists, apart from and besides all generation, destruction, change, motion, &c., a certain Immovable Nature (ἀκίνητός τις φύσις — a. 34). Indeed their own doctrine — That all things both are and are not — would seem to imply an universal stationary condition rather than universal change (a. 38). There can be no change; for there is no prospective terminus which can be reached by change. Every thing is assumed as already existing.
We have now to remark upon the special doctrine of Protagoras — πᾶν τὸ φαινόμενον ἀληθές. If we grant that perception is always true upon matters strictly belonging to it, still phantasy is not identical with perception and we cannot say that what appears to the phantasy is always true (τὸ φαινόμενον — which implies a reference to φαντασία — p. 1010, b. 2), Besides, it is strange that thinkers should puzzle themselves about the questions: Whether the magnitude and colour of objects is that which appears to a spectator near or to a spectator far off? and to a spectator healthy or jaundiced? Whether the weight of an object is as it appears to a weak or to a strong man? Whether objects are truly what they appear to men awake or to men asleep? Their own actions show that they do not think there is any doubt; for if, being in Libya, they happen to dream that they are in Athens, none of them ever think of going to the Odeium (b. 5-11). Moreover, respecting the future, as Plato remarks, the anticipations of the ignorant man are not so trustworthy as those of the physician, whether a patient will recover or not (b. 14). Then, again, in respect of present sensations, the perception of sight is not equally trustworthy with the perception of smell about a question of odour (b. 17); and the perception of smell will never report at the same time and about the same thing, that it is at once fragrant and not fragrant; nor, indeed, at different times about the affection itself, but only about the subject to which the affection belonged (b. 20). The same wine which tasted sweet last month, may now taste not sweet; but the sweet taste itself is the same now and last month, and the reports of the sense are never contradictory on this point. The sweet taste which is to come in the future will be of necessity like the sweet taste in the past. Now such necessity is abrogated by all those reasonings which affirm at once the two members of the Antiphasis. These reasonings disallow all essence of every thing, and all necessity; for whatever is necessary, cannot be at once both thus and not thus (b. 21-30).
On the whole, if nothing exist except Percepta, nothing can exist without animated beings; since without these last there can be no perception. It is indeed true, perhaps, that under such a supposition there exist neither Percepta nor acts of Perception (which are affections of the Percipient); but that the Substrata which cause Perception should not exist even without Perception — is an impossibility (p. 1010, b. 33: τὸ δὲ τὰ ὑποκείμενα μὴ εἶναι, ἃ ποιεῖ τὴν αἴσθησιν, καὶ ἄνευ αἰσθήσεως, ἀδύνατον). Perception is not perception of itself; there exists besides, apart from perception, something else which must necessarily be prior to perception. For the Movens is by nature prior to the Motum; and this is not the less true, though each of these two is enunciated in relation to the other (b. 35).
A difficulty is often started, and enquiry made, Who is to be the judge of health and sickness? Whom are we to recognize as the person to judge rightly in each particular case? Persons might as well raise difficulty and make enquiry, Whether we are now awake or asleep? It is plain by men’s actual conduct that they have no real doubt upon the point in any particular case; and both these enquiries arise from the same fundamental mistake — that men require to have every thing demonstrated, and will recognize nothing without demonstration. (Alex. says in Scholia, p. 675, b. 3: ἔστι γὰρ πρὸς ἃ ἐκ φύσεως βέλτιον ἔχομεν ἢ ὥστε δεῖσθαι τῆς περὶ αὐτῶν ἀποδείξεως· ἔστι δὲ ταῦτα αἵ τε αἰσθήσεις, καὶ τὰ ἀξιώματα καὶ αἱ φυσικαί τε καὶ κοιναὶ ἔννοιαι.) Those who sincerely and seriously feel this difficulty, may be expected to acquiesce in the explanation here given (p. 1011, a. 2-14). But those who put forward the difficulty merely for the sake of argument, must be informed that they require an impossibility. They require to have a refutative case made out against them (which can only be done by reducing them to a συλλογισμὸς ἀντιφάσεως); yet they themselves begin by refusing to acknowledge this refutation as sufficient, for they maintain the thesis — That both members of the Antiphasis are alike and equally true (a. 16; compare Alex. Schol., p. 675, b. 20-28).
Those who maintain this last-mentioned thesis say, in other words, That every thing which appears true, is true. But this thesis of theirs cannot be defended except by the admission that every thing is relative, and that nothing is absolute. Accordingly they must take care to announce their thesis, not in absolute terms as it now stands, but in terms strictly relative: Every thing which appears true, appears true to some individual — at a certain moment of time — under certain circumstances and conditions (p. 1011, a. 24). For, if they affirm, in absolute phrase, that all things are alike false and true, on the ground that what appears true is true, urging that the same things do not appear true either to different persons, or to the same person at different times — nay, sometimes even to the same person at the same time, as may be seen by handling a pebble between two crossed fingers (ἐν τῇ ἐπαλλάξει τῶν δακτύλων — a. 33), so that it appears two to the touch, but only one to the sight; — we shall reply, that there is no such contradiction of judgment, if they confine themselves to the same person, the same time, and one and the same sense. In these cases, there is only one affirmation which appears to be true, and therefore, according to their theory, that affirmation is true. They are not, therefore, justified in concluding that every thing is alike true and false (b. 1).
They can only escape this refutation by avoiding to say, This is true, and by saying, This is true to such an individual, at such a time, &c.; that is, by making every affirmation relative to some person’s opinion or perception. Hence the inference is, that nothing either ever has occurred or ever will occur, without the antecedent opinion of some person (μηθενὸς προδοξάσαντος — p. 1011, b. 6): if any thing ever has so occurred, it cannot be true that all things are relative to opinion. Moreover, if the Relatum be one, it must be relative to some one, some definite, Correlate; and, even if the same Relatum be both half and equal, it will not be equal in reference to a double Correlate, but half in reference to a double, and equal in reference to an equal (b. 9). Moreover, if homo and conceptum have both of them no more than a relative existence — that is, if both of them exist only in correlation with a concipiens — then the concipiens cannot be homo; it will be the conceptum that is homo. And, if every individual thing have existence only in relation to a concipiens, this concipiens must form the Correlate to an infinite number of Relata (b. 12). (All this is very briefly and obscurely stated in Aristotle. The commentary of Alexander is copious and valuable: one might suppose that he had before him a more ample text; for it is difficult to find in the present text all that his commentary states.)
Let thus much be said to establish the opinion, That the two members of the Antiphasis (the Affirmative and the Negative) are not both true at the same time. We have shown whence it arises that some persons suppose both to be true; and what are the consequences in which those who hold this opinion entangle themselves. Accordingly, since both sides of the Antiphasis cannot be truly predicated of the same subject, it is impossible that opposite attributes can belong at the same time to the same subject (p. 1011, b. 17: οὐδὲ τἀναντία ἅμα ὑπάρχειν ἐνδέχεται τῷ αὐτῷ). For one of these opposites includes in itself privation, and privation of a certain real essence; now privation is the negation of a certain definite genus. And, since affirmation and negation cannot be truly applied at the same time, it follows that opposite attributes cannot belong at the same time to the same subject. At least it is only possible thus far: one may belong to it absolutely, the other secundum quid; or both of them secundum quid only (τῶν μὲν γὰρ ἐναντίων θάτερον στέρησίς ἐστιν οὐχ ἧττον, οὐσίας δὲ στέρησις ἀπόφασίς ἐστιν ἀπό τινος ὡρισμένου γένους — b. 20).
But, also, there can be nothing intermediate between the two members of the Antiphasis; we must of necessity either affirm or deny any one thing of any other (p. 1011, b. 24). This will appear clearly, when we have first defined what is Truth and Falsehood. To say that Ens is not, or that Non-Ens is, is false: To say that Ens is, or that Non-Ens is not, is true. Accordingly, he who predicates est — or he who predicates non est — will speak truly or speak falsely, according as he applies his predicate to Ens or to Non-Ens. But he cannot, either in application to Ens or to Non-Ens, predicate est aut non est (b. 29). Such a predication would be neither true nor false, but improper and unmeaning. (I follow at b. 27 the text of the Berlin edition: ὥστε καὶ ὁ λέγων εἶναι ἢ μὴ ἀληθεύσει ἢ ψεύσεται — which seems to me here better than that of Bonitz, who puts ὥστε καὶ ὁ λέγων τοῦτο εἶναι ἢ μὴ ἀληθεύσει ἢ ψεύσεται — following Alexander’s explanation, Schol., p. 680, a. 33, which I cannot think to be correct, though Bonitz praises it much. Aristotle defines Truth and Falsehood: When you say Ens est, or Non-Ens non est, you speak truth; when you say Ens non est, or Non-Ens est, you speak falsehood. Accordingly, when you employ the predicate est, or when you employ the predicate non est, you will speak truly or falsehood, according as the subject with which you join it is Ens or is Non-Ens. But neither with respect to the subject Ens nor with respect to the subject Non-Ens, can you employ the disjunctive predicate — est aut non est.)
Again, a medium between the two horns of the Antiphasis must be either a medium between opposites, like grey between white and black, or like the neither between man and horse. If it be the latter, it will never change; for all change is either from a negative to its affirmative (non-bonum to bonum) or vice versâ: now that which is both non-homo and non-equus must change, if it change at all, into that which is both homo and equus; but this is impossible. We see change always going on; but it is always change either into one of the two extremes or into the medium between them. But can we assume that there is such a medium (so that the case supposed will belong to the analogy of grey, halfway between white and black)? No, we cannot assume it; for, if we granted it, we should be forced to admit that there was change into white not proceeding from that which is not white: now nothing of the kind is ever perceived. There cannot therefore be any admissible medium halfway between the two members of the Antiphasis — something which is neither white nor not-white, neither black nor not-black (p. 1011, b. 35: εἰ δ’ ἔστι μεταξύ — if such medium be admitted — καὶ οὕτως εἴη ἄν τις εἰς λευκὸν οὐκ ἐκ μὴ λευκοῦ γένεσις· νῦν δ’ οὐχ ὁρᾶται).
Furthermore, whatever our intelligence understands or reasons upon, it deals with as matter affirmed or denied. The very definition of truth and falsehood recognizes them as belonging only to affirmation or negation: when we affirm or deny in a certain way we speak truth; when in another way, we speak falsely. Nothing is concerned but affirmation and denial (i.e., there is no mental operation midway between the two — p. 1012, a. 2-5). If there be any such medium or midway process, it is not confined to this or that particular Antiphasis, but belongs alike to all, and must lie apart from all the different Antiphases — at least if it is to be talked of as a reality, and not as a mere possible combination of words; so that the speaker will neither speak truth, nor not speak truth; which is absurd (a. 7). It must also lie apart both from Ens and from Non-Ens; so that we should be compelled to admit a certain mode of change of Essence, which yet shall neither be generation nor destruction; which is impossible. (According to Aristotle’s definition, all change of οὐσία must be either Generation, i.e., passage from τὸ μὴ ὄν to τὸ ὄν, or Destruction, i.e., passage from τὸ ὄν to τὸ μὴ ὄν. — See Alex. Schol. p. 681, b. 30-40.)