On the meaning of τὸ ἐνδεχόμενον, translated above, in the table, “possible (logically) to be,â€� and its relation to τὸ δυνατόν, see Waitz, ad Organ. I. pp. 375-8. Compare Prantl. Gescht. der Logik, I. pp. 166-8.
[46] Aristot. De Interpr. p. 21, a. 32: τὸ δὲ μὴ ὄν, ὅτι δοξαστόν, οὐκ ἀληθὲς εἰπεῖν ὄν τι· δόξα γὰρ αὐτοῦ οὐκ ἔστιν ὅτι ἔστιν, ἀλλ’ ὅτι οὐκ ἔστιν. Τὸ μὴ ὄν is the true description of that which Aristotle improperly calls δύναμις ἣ οὐδέποτε ἐνέργειά ἐστιν.
The triple enumeration given by Aristotle (1. Actuality without Potentiality. 2. Actuality with Potentiality. 3. Potentiality without Actuality) presents a neat symmetry which stands in the place of philosophical exactness.
The contrast of Actual and Potential stands so prominently forward in Aristotle’s First Philosophy, and is, when correctly understood, so valuable an element in First Philosophy generally, that we cannot be too careful against those misapplications of it into which he himself sometimes falls. The sense of Potentiality, as including the alternative of either affirmative or negative — may be or may not be — is quite essential in comprehending the ontological theories of Aristotle; and when he professes to drop the may not be and leave only the may be, this is not merely an equivocal sense of the word, but an entire renunciation of its genuine sense. In common parlance, indeed, we speak elliptically, and say, It may be, when we really mean, It may or may not be. But the last or negative half, though not expressly announced, is always included in the thought and belief of the speaker and understood by the hearer.[47]
[47] See Trendelenburg ad Aristot. De Animâ, pp. 303-307.
Many logicians, and Sir William Hamilton very emphatically, have considered the Modality of propositions as improper to be included in the province of Logic, and have treated the proceeding of Aristotle in thus including it, as one among several cases in which he had transcended the legitimate boundaries of the science.[48] This criticism, to which I cannot subscribe, is founded upon one peculiar view of the proper definition and limits of Logic. Sir W. Hamilton lays down the limitation peremptorily, and he is warranted in doing this for himself; but it is a question about which there has been great diversity of view among expositors, and he has no right to blame others who enlarge it. My purpose in the present volume is to explain how the subject presented itself to Aristotle. He was the first author that ever attempted to present Logic in a scientific aspect; and it is hardly fair to try him by restrictions emanating from critics much later. Yet, if he is to be tried upon this point, I think the latitude in which he indulges preferable to the restricted doctrine of Sir W. Hamilton.
[48] See pp. 143-5 of the article, “Logic,� in Sir William Hamilton’s Discussions on Philosophy — a very learned and instructive article, even for those who differ from most of its conclusions. Compare the opposite view, as advocated by M. Barthélemy St. Hilaire, Logique d’Aristote, Préface, pp. lxii.-lxviii.
In the treatise now before us (De Interpretatione) Aristotle announces his intention to explain the Proposition or Enunciative Speech, the conjunction of a noun and a verb; as distinguished, first, from its two constituents (noun and verb) separately taken; next, from other modes of speech, also combining the two (precative, interrogative, &c.). All speech (he says), the noun or verb separately, as well as the proposition conjointly, is, in the first instance, a sign of certain mental states common to the speaker with his hearers; and, in the second instance, a sign of certain things or facts, resembling (or correlating with) these mental states.[49] The noun, pronounced separately, and the verb, pronounced separately, are each signs of a certain thought in the speaker’s mind, without either truth or falsehood; the Proposition, or conjunction of the two, goes farther and declares truth or falsehood. The words pronounced (he says) follow the thoughts in the mind, expressing an opinion (i.e. belief or disbelief) entertained in the mind; the verbal affirmation or negation gives utterance to a mental affirmation or negation — a feeling of belief or disbelief — that something is, or that something is not.[50] Thus, Aristotle intends to give a theory of the Proposition, leaving other modes of speech to Rhetoric or Poetry:[51] the Proposition he considers under two distinct aspects. In its first or subjective aspect, it declares the state of the speaker’s mind, as to belief or disbelief. In its second or objective aspect, it declares a truth or falsehood correlating with such belief or disbelief, for the information of the hearer. Now the Mode belonging to a proposition of this sort, in virtue of its form, is to be true or false. But there are also other propositions — other varieties of speech enunciative — which differ from the Simple or Assertory Proposition having the form is or is not, and which have distinct modes belonging to them, besides that of being true or false. Thus we have the Necessary Proposition, declaring that a thing is so by necessity, that it must be so, or cannot but be so; again, the Problematical Proposition, enunciating that a thing may or may not be so. These two modes attach to the form of the proposition, and are quite distinct from those which attach to its matter as simply affirmed or denied; as when, instead of saying, John is sick, we say, John is sick of a fever, John is dangerously sick, with a merely material modification. Such adverbs, modifying the matter affirmed or denied, are numerous, and may be diversified almost without limit. But they are not to be placed in the same category with the two just mentioned, which modify the form of the proposition, and correspond to a state of mind distinct from simple belief or disbelief, expressed by a simple affirmation or negation.[52] In the case of each of the two, Aristotle has laid down rules (correct or incorrect) for constructing the legitimate Antiphasis, and for determining other propositions equipollent to, or following upon, the propositions given; rules distinct from those applying to the simple affirmation. When we say of anything, It may be or may not be, we enunciate here only one proposition, not two; we declare a state of mind which is neither belief nor disbelief, as in the case of the Simple Proposition, but something wavering between the two; yet which is nevertheless frequent, familiar to every one, and useful to be made known by a special form of proposition adapted to it — the Problematical. On the other hand, when we say, It is by necessity — must be — cannot but be — we declare our belief, and something more besides; we declare that the supposition of the opposite of what we believe, would involve a contradiction — I would contradict some definition or axiom to which we have already sworn adherence. This again is a state of mind known, distinguishable, and the same in all, subjectively; though as to the objective correlate — what constitutes the Necessary, several different opinions have been entertained.
[49] Aristot. De Interpr. p. 16, a. 3-8: ἔστι μὲν οὖν τὰ ἐν τῇ φωνῇ τῶν ἐν τῇ ψυχῇ παθημάτων σύμβολα — ὧν μέντοι ταῦτα σημεῖα πρώτως, ταὐτὰ πᾶσι παθήματα τῆς ψυχῆς, καὶ ὧν ταῦτα ὁμοιώματα, πράγματα ἤδη ταὐτά. Ibid. a. 13: τὰ μὲν οὖν ὀνόματα αὐτὰ καὶ τὰ ῥήματα ἔοικε τῷ ἄνευ συνθέσεως καὶ διαιρέσεως νοήματι — οὔτε γὰρ ψεῦδος οὔτ’ ἀληθές πω. Ib. p. 17, a. 2: λόγος ἀποφαντικὸς, ἐν ᾧ τὸ ἀληθεύειν ἢ ψεύδεσθαι ὑπάρχει. Compare p. 20, a. 34.
[50] Aristot. De Interpret. p. 23, a. 32: τὰ μὲν ἐν τῇ φωνῇ ἀκολουθεῖ τοῖς ἐν τῇ διανοίᾳ, ἐκεῖ δὲ ἐναντία δόξα ἡ τοῦ ἐναντίου, &c. Ib. p. 24, b. 1: ὥστε εἴπερ ἐπὶ δόξης οὕτως ἔχει, εἰσὶ δὲ αἱ ἐν τῇ φωνῇ καταφάσεις καὶ ἀποφάσεις σύμβολα τῶν ἐν τῇ ψυχῇ, δῆλον ὅτι καὶ καταφάσει ἐναντία μὲν ἀπόφασις ἥ περὶ τοῦ αὐτοῦ καθόλου, &c. Ib. p. 17, a. 22: ἔστι δὲ ἡ ἁπλῆ ἀπόφανσις φωνὴ σημαντικὴ περὶ τοῦ ὑπάρχειν τι ἢ μὴ ὑπάρχειν, &c.