Again, the theory that both members of the Antiphasis are alike true, is intended by its authors to apply universally or not universally. Every thing is both white and not white, Ens and Non-Ens; or this is true with some propositions, but not with regard to others. If the theorists take the latter ground and allow some exceptions, so far at least as those exceptions reach, firm truth is left (αὗται ἂν εἶεν ὁμολογούμεναι — p. 1008, a. 11). But, if they take the former ground and allow no exceptions, they may still perhaps say: Wherever you can affirm with truth, we can also deny with truth; but, wherever we can deny with truth, we cannot in every case affirm with truth (a. 15). Meeting them upon this last ground, we remark that at any rate some negative propositions are here admitted to be knowable, and we obtain thus much of settled opinion; besides, wherever the negative is knowable, the corresponding affirmative must be still more knowable (a. 18). If they take the former ground and say that, wherever the negative is true, the affirmative is true also, they must either mean that each of them is true separately, or that neither of them is true separately but that both are true when enunciated together in a couple (a. 19). If they mean the latter, they do not talk either of these things or of any thing else: there is neither speech nor speaker, nothing but non-entity; and how can non-entity either speak or walk (a. 22)? Every thing would be confounded in one. If they mean the former — that affirmative and negative are each alike true taken separately, we reply that, since this must be true as much respecting one subject as respecting another, so there can be no distinction or difference between one subject and another; all must be alike and the same; if there be any difference of any kind, this must constitute a special and exceptional matter, standing apart from the theory now under discussion. Upon this view of the theory in question, then, as well as upon the preceding, we are landed in the same result: all things would be confounded into one (a. 27). All men would speak truly and all men alike (including the theorist himself, by his own admission) would speak falsely. Indeed in discussing with this theorist we have nothing to talk about; for he says nothing. He does not say, It is thus; he does not say, It is not thus; he says, It is both thus and not thus: then, again, he negatives both, saying, It is neither thus nor not thus; so that there is nothing definite in what he says (a. 32).
Again, let us ask, Does he who believes things to be so, believe falsely, and he who believes things not to be so and so, believe falsely also, while he who believes both at once, believes truly? If this last person believes truly, what is meant by the common saying that such and such is the constitution of nature? If you even say that the last person does not indeed believe truly, but believes more truly than he who believes the affirmative alone, or he who believes the negative alone, we still have something definite in the constitution of nature, something which is really true, and not true and false at the same time. But, if there be no more truly or less truly — if all persons alike and equally speak truly and speak falsely — speech is useless to such persons; what they say, they at the same time unsay. If the state of their minds really corresponds to this description — if they believe nothing, but at once think so and so and do not think so and so — how do such persons differ from plants (b. 3-12; see Alexander’s Scholion, p. 665, b. 9-17 Br., about the explanation of μᾶλλον, and the distinction between λέγειν and ὑπολαμβάνειν, p. 665, b. 31, seq.)?
It is certain, however, that these theorists are not like plants, and do not act as such in matters of ordinary life. They look for water, when thirsty; they keep clear of falling into a well or over a precipice. In regard to what is desirable or undesirable, at least, they do not really act upon their own theory — That both members of the Antiphasis are equally true and equally false. They act upon the contrary theory — That one of the members is true, and the other false. But, if these theorists, admitting that they act thus, say that they do not act thus with any profession of knowing the truth, but simply on the faith of appearance and greater probability, we reply that this ought to impose upon them a stronger sense of duty in regard to getting at the truth. The state of Opinion stands to that of Knowledge in the same relation as that of sickness to health (p. 1008, b. 12-31).
Finally, to follow up this last argument, even if we grant to these theorists that both members of the Antiphasis are true, still there are degrees of truth: the More and the Less pervades the constitution of nature (p. 1008, b. 32). We shall not surely affirm that two and three are equally even; nor shall we say, when any one affirms four to be five, that he commits an equal error with one who affirms four to be a thousand. Clearly one of these persons is more near to the truth, the other is less near to the truth. But, if there be such a thing as being nearer to the truth, there must surely be some truth to which you have come nearer; and, even if this be denied, yet at least what we have already obtained (the ἐγγύτερον τῆς ἀληθείας) is something firmer and of a more truth-like character. We shall thus have got rid of that unqualified theory which forbids all definite conceptions of the intellect (κἂν εἰ μή ἐστιν, ἀλλ’ ἤδη γέ τι ἐστὶ βεβαιότερον καὶ ἀληθινώτερον, καὶ τοῦ λόγου ἀπηλλαγμένοι ἂν εἴημεν τοῦ ἀκράτου καὶ κωλύοντός τι τῇ διανοίᾳ ὁρίσαι — p. 1009, a. 2).
Having thus completed his refutation of the “unqualified theory,� which declares both members of the Antiphasis to be alike true, Aristotle passes to the examination of the Protagorean doctrine “Homo Mensura:� he affirms that it proceeds from the same mode of thinking, and that the two must stand or fall together. For, if all things which appear true are true, all things must be at once true and false; since the opposition of men’s opinions is a notorious fact, each man thinking his own opinions true and his opponent’s opinions false (p. 1009, a. 16).
Aristotle here distinguishes between two classes of reasoners, both of whom he combats, but who require to be dealt with in a very different manner: (1) Those who are sincerely convinced of what they affirm; (2) Those who have no sincere conviction, but merely take up the thesis as a matter for ingenious argument (λόγου χάριν), and will not relinquish it until they are compelled by a strong case made out against them. The first require persuasion, for their ignorance may be easily cured, and the difficulties whereby they are puzzled may be removed; the second require to be constrained by a forcible Elenchus or refutation, which may correct their misuse of dialectic and language (p. 1009, a. 22).
Aristotle begins with the first class. The difficulties which perplex them proceed from sensible things (ἐκ τῶν αἰσθητῶν — p. 1009, a. 23). They perceive contrary things generated by the same; and this leads them to believe that contraries are both alike real, and that the two members of the Antiphasis are alike true. For, since Non-Ens cannot be generated, both the two contraries must have pre-existed together as Entia, prior to the generation in the thing as it then stood (a. 25). This is the opinion of Anaxagoras, who affirms that every thing is mixed in every thing; and of Demokritus, who affirms that Plenum and Inane — in other words. Ens and Non-Ens — exist alike and together in every part (a. 28). To these reasoners we reply, that in a certain sense they are right, in a certain sense wrong. The term Ens is used in two senses: the same thing may therefore be at once Ens and Non-Ens, but not in the same sense; moreover, from Non-Ens in one sense something may be generated, but not from Non-Ens in the other. The same thing may be at once two opposites in power, but not in act (δυνάμει μὲν γὰρ ἐνδέχεται ἅμα ταὐτὸ εἶναι τὰ ἐναντία, ἐντελεχείᾳ δ’ οὔ — a. 35). We must farther remind these reasoners that the basis on which they proceed is not universally admissible; for there are various Entia of completely distinct and different essence, in which there is neither movement nor generation nor destruction of any sort (a. 38).
The doctrine held by Protagoras — That what appears true is truth, comes from the same source as the other doctrine — That both members of the Antiphasis are true. Both doctrines proceed from the sensible world (ὁμοίως δὲ καὶ ἡ περὶ τὰ φαινόμενα ἀλήθεια ἐνίοις ἐκ τῶν αἰσθητῶν ἐλήλυθεν — p. 1009, b. 2; ὁμοίως refers back to a. 23 — αὕτη ἡ δόξα, the other doctrine). Demokritus, Protagoras, and others observe that sensible phenomena are differently appreciated by different men, by other animals, and even by the same animal or man at different times. They do not think that truth upon these points of difference can be determined by a majority of voices. Demokritus says that either there is nothing true, or that we cannot know what it is (b. 10). These reasoners identified intelligence with sensible perception, and considered that this latter implied a change in the subject (b. 13): they conceived that what appeared to sense was necessarily true. Empedokles, Demokritus, Parmenides, Anaxagoras, Homer, &c., all lay down the doctrine, that the intelligence of men is varied with and determined by their sensible perceptions. They thought that men of wrong intelligence were nevertheless intelligent men, though their intelligence did not carry them to the same conclusions (b. 30); that if, both in one case and in the other, there were acts of intelligence, there must be realities corresponding to both, justifying the affirmative as well as the negative (b. 33).
That sincere and diligent enquirers should fall into these errors is very discouraging; but we must remark that their errors originated from this — that, while investigating the truth respecting Entia, they supposed that Entia were only the Percepta or Percipibilia (p. 1010, a. 2). Now in these Entia Perceptionis there is a great deal of the Indefinite and of mere Potential Entity (a. 3). Hence the theories of these reasoners were plausible, though not true. They saw that all the Entia Perceptionis were in perpetual movement, and they thought it impossible to predicate any thing with truth respecting what was at all times and in every way changing (a. 9). Kratylus and the Herakleitizers pushed this to an extreme. Even against their reasoning, we have something to say in reply. We grant that they have some ground for imagining that what undergoes change does not exist at the moment when it changes (a. 16). Yet even here there is room for dispute; for that which is in the act of casting off, still retains something of that which is being cast off; and of that which is being generated, something must already be in existence. As a general doctrine, if something is in course of being destroyed, something must be in existence; and, if something is in course of being generated, there must exist something out of which it proceeds and by which it is being generated; nor can this go back ad infinitum (a. 22). Dropping this argument, however, let us advance another. Change as to Quantity is not the same as change as to Quality or Form. Let us grant that, as to Quantity, there is change continuous and perpetual — growth or decay — no such thing as stationary condition. But all our knowledge relates to Quality or Form, in which there is no continuous change (a. 24: κατὰ μὲν οὖν τὸ ποσόν, ἔστω μὴ μένον· ἀλλὰ κατὰ τὸ εἶδος ἅπαντα γιγνώσκομεν. — Compare Alex. Schol., p. 671, b. 5-22; p. 670, a. 36: Bonitz has good remarks in his note, pp. 202-204.).
Again, we have a farther reproach to make to these reasoners. Their argument is based only on the Percepta or Percipienda; yet, even as to these it is true only as to the minority and untrue as to the majority. It is true merely as far as the sublunary Percepta; but as to the superlunary or celestial it is the reverse of truth. Our earth and its neighbourhood is indeed in continual generation and destruction; but this is an insignificant part of the whole. In affirming any thing respecting the whole, we ought to follow the majority rather than the minority (p. 1010, a. 28-31).