CHAPTER VIII.

83Analyt. Post. I. xxix. p. 87, b. 5-18. Aristotle gives an example to illustrate this general doctrine: ἥδεσθαι, τὸ κινεῖσθαι, τὸ ἠρεμίζεσθαι, τὸ μεταβάλλειν. As he includes these terms and this subject among the topics for demonstration, it is difficult to see where he would draw a distinct line between topics for Demonstration and topics for Dialectic.

There cannot be demonstrative cognition of fortuitous events,84for all demonstration is either of the necessary or of the customary. Nor can there be demonstrative cognition through sensible perception. For though by sense we perceive a thing as such and such (through its sensible qualities), yet we perceive it inevitably ashoc aliquid,hic,et nunc. But the Universal cannot be perceived by sense; for it is neitherhicnornunc, butsemper et ubique.85Now demonstrations are all accomplished by means of the Universal, and demonstrative cognition cannot therefore be had through sensible perception. If the equality of the three angles of a triangle to two right angles were a fact directly perceivable by sense, we should still have looked out for a demonstration thereof: we should have no proper scientific cognition of it (though some persons contend for this): for sensible perception gives us only particular cases, and Cognition or Science proper comes only through knowing the Universal.86If, being on the surface of the moon, we had on any one occasion seen the earth between us and the sun, we could not have known from that single observation that such interposition is the cause universally of eclipses. We cannot directly by sense perceive the Universal, though sense is theprincipiumof the Universal. By multiplied observation of sensible particulars, we can hunt out and elicit the Universal, enunciate it clearly and separately, and make it serve for demonstration.87The Universal is precious, because it reveals the Cause or διότι, and is therefore more precious, not merely than sensible observation, but also than intellectual conception of the ὅτι only, where the Cause or διότι lies apart, and is derived from a higher genus. Respecting First Principles orSumma Genera, we must speak elsewhere.88It is clear, therefore, that no demonstrable matter can be known, properly speaking, from direct perception of sense; though there are cases in which nothing but the impossibility of direct observation drives us upon seeking for demonstration. Whenever we can get an adequate number of sensible observations, we can generalize the fact; and in some instances we may perhaps not seek for any demonstrative knowledge (i.e.to explain it by any higher principle). If we could see the pores in glass and the light passing through them, we should learn through many such observations why combustion arises on the farther side of the glass; each of our observations would have been separate and individual, but we should by intellect generalize the result that all the cases fall under the same law.89

84Analyt. Post. I. xxx. p. 87, b. 19-27.

85Ibid. xxxi. p. 87, b. 28: εἰ γὰρ καὶ ἔστιν ἡ αἴσθησις τοῦ τοιοῦδε καὶ μὴ τοῦδέ τινος, ἀλλâ€™ αἰσθάνεσθαί γε ἀναγκαῖον τόδε τι καὶ ποῦ καὶ νῦν.

86Ibid. b. 35: δῆλον ὅτι καὶ εἰ ἦν αἰσθάνεσθαι τὸ τρίγωνον ὅτι δυσὶν ὀρθαῖς ἴσας ἔχει τὰς γωνίας, ἐζητοῦμεν ἂν ἀπόδειξιν, καὶ οὐχ (ὥσπερ φασί τινες) ἠπιστάμεθαÂ· αἰσθάνεσθαι μὲν γὰρ ἀνάγκη καθâ€™ ἕκαστον, ἡ δâ€™ ἐπιστήμη τῷ τὸ καθόλου γνωρίζειν ἐστίν.Euclid, in the 20th Proposition of his first Book, demonstrates that any two sides of a triangle are together greater than the third side. According to Proklus, the Epikureans derided the demonstration of such a point as absurd; and it seems that some contemporaries of Aristotle argued in a similar way, judging by the phrase ὥσπερ φασί τινες.

Euclid, in the 20th Proposition of his first Book, demonstrates that any two sides of a triangle are together greater than the third side. According to Proklus, the Epikureans derided the demonstration of such a point as absurd; and it seems that some contemporaries of Aristotle argued in a similar way, judging by the phrase ὥσπερ φασί τινες.

87Analyt. Post. I. xxxi. p. 88, a. 2: οὐ μὴν ἀλλâ€™ ἐκ τοῦ θεωρεῖν τοῦτο πολλάκις συμβαῖνον, τὸ καθόλου ἂν θηρεύσαντες ἀπόδειξιν εἴχομενÂ· ἐκ γὰρ τῶν καθâ€™ ἕκαστα πλειόνων τὸ καθόλου δῆλον. Themistius, p. 62, Sp.: ἀρχὴ μὲν γὰρ ἀποδείξεως αἴσθησις, καὶ τὸ καθόλου ἐννοοῦμεν διὰ τὸ πολλάκις αἰσθέσθαι.

88Analyt. Post. I. xxxi. p. 88, a. 6: τὸ δὲ καθόλου τίμιον, ὅτι δηλοῖ τὸ αἴτιονÂ· ὥστε περὶ τῶν τοιούτων ἡ καθόλου τιμιωτέρα τῶν αἰσθήσεων καὶ τῆς νοήσεως, ὅσων ἕτερον τὸ αἴτιονÂ· περὶ δὲ τῶν πρώτων ἄλλος λόγος.By τὰ πρῶτα, he means the ἀρχαὶ of Demonstration, which are treated especially in II. xix. See Biese, Die Philos. des Aristoteles, p. 277.

By τὰ πρῶτα, he means the ἀρχαὶ of Demonstration, which are treated especially in II. xix. See Biese, Die Philos. des Aristoteles, p. 277.

89Analyt. Post. I. xxxi. p. 88, a. 9-17. ἔστι μέντοι ἔνια ἀναγόμενα εἰς αἰσθήσεως ἔκλειψιν ἐν τοῖς προβλήμασινÂ· ἔνια γὰρ εἰ ἑώρωμεν, οὐκ ἂν ἐζητοῦμεν, οὐχ ὡς εἰδότες τῷ ὁρᾷν, ἀλλâ€™ ὡς ἔχοντες τὸ καθόλου ἐκ τοῦ ὁρᾷν.The text of this and the succeeding words seems open to doubt, as well as that of Themistius (p. 63). Waitz in his note (p. 374) explains the meaning clearly:â€” â€œnon ita quidem ut ipsa sensuum perceptio scientiam afferat; sed ita ut quod in singulis accidere videamus, idem etiam in omnibus accidere coniicientes universe intelligamus.â€�

The text of this and the succeeding words seems open to doubt, as well as that of Themistius (p. 63). Waitz in his note (p. 374) explains the meaning clearly:â€” â€œnon ita quidem ut ipsa sensuum perceptio scientiam afferat; sed ita ut quod in singulis accidere videamus, idem etiam in omnibus accidere coniicientes universe intelligamus.â€�

Aristotle next proceeds to refute, at some length, the supposition, that theprincipiaof all syllogisms are the same. We see at once that this cannot be so, because some syllogisms are true, others false. But, besides, though there are indeed a few Axioms essential to the process of demonstration, and the same in all syllogisms, yet these are not sufficient of themselves for demonstration. There must farther be other premisses or matters of evidence â€” propositions immediately true (or established by prior demonstrations) belonging to each branch of Science specially, as distinguished from the others. Our demonstration relatestothese special matters or premisses, though it is accomplishedout ofor by means of the common Axioms.90

90Analyt. Post. I. xxxii. p. 88, a. 18-b. 29. αἱ γὰρ ἀρχαὶ διτταί, ἐξ ὧν τε καὶ περὶ ὃÂ· αἱ μὲν οὖν ἐξ ὧν κοιναί, αἱ δὲ περὶ ὅ ἴδιαι, οἷον ἀριθμός, μέγεθος. Compare xi. p. 77, a. 27. See BarthÃ©lemy St. Hilaire, Plan GÃ©nÃ©ral des Derniers Analytiques, p. lxxxi.

Science or scientific Cognition differs from true Opinion, and thecognitumfrom theopinatum, herein, that Science is of the Universal, and through necessary premisses which cannot be otherwise; while Opinion relates to matters true, yet which at the same time may possibly be false. The belief in a proposition which is immediate (i. e., undemonstrable) yet not necessary, is Opinion; it is not Science, nor is it NoÃ»s or Intellect â€” theprincipiumof Science or scientific Cognition. Such beliefs arefluctuating, as we see every day; we all distinguish them from other beliefs, which we cannot conceive not to be true and which we call cognitions.91But may there not be Opinion and Cognition respecting the same matters? There may be (says Aristotle) in different men, or in the same man at different times; but not in the same man at the same time. There may also be, respecting the same matter, true opinion in one manâ€™s mind, and false opinion in the mind of another.92

91Analyt. Post. I. xxxiii. p. 88, b. 30-p. 89, a. 10.

92Ibid. p. 89, a. 11-b. 6. That eclipse of the sun is caused by the interposition of the moon was to the astronomer Hipparchos scientific Cognition; for he saw that itcould notbe otherwise. To the philosopher Epikurus it was Opinion; for he thought that itmightbe otherwise (Themistius, p. 66, Spengel).

With some remarks upon Sagacity, or the power of divining a middle term in a time too short for reflection (as when the friendship of two men is on the instant referred to the fact of their having a common enemy), the present book is brought to a close.93

93Ibid. xxxiv. p. 89, b. 10-20.

Aristotle begins the Second Book of the Analytica Posteriora by an enumeration and classification of Problems or Questions suitable for investigation. The matters knowable by us may be distributed into four classes:â€”

Ὅτι.Διότι.Εἰ ἔστι.Τί ἐστι.1. Quod.2. Cur.3. An sit.4. Quid sit.

Under the first head come questions of Fact; under the second head, questions of Cause or Reason; under the third, questions of Existence; under the fourth, questions of Essence. Under the first head we enquire, Whether a fact or event is so or so? Whether a given subject possesses this or that attribute, or is in this or that condition? enumerating in the question the various supposable alternatives. Under the second head, we assume the first question to have been affirmatively answered, and we proceed to enquire, What is the cause or reason for such fact, or such conjunction of subject and attribute? Under the third head, we ask, Does a supposed subject exist? And if the answer be in the affirmative, we proceed to enquire, under the fourth head, What is the essence of the subject?1

1Analyt. Post. II. i. p. 89, b. 23, seq. Themistius observes, p. 67, Speng.: ζητοῦμεν τίνυν ἢ περὶ ἁπλοῦ τινὸς καὶ ἀσυνθέτου, ἢ περὶ συνθέτου καὶ ἐν προτάσει. Themistius has here changed Aristotleâ€™s order, and placed the third and fourth heads before the first and second. Compare Schol. p. 240, b. 30; p. 241, a. 18. The Scholiast complains of the enigmatical style of Aristotle: τῇ γριφώδει τοῦ ῥητοῦ ἐπαγγελία (p. 240, b. 25).

We have here two distinct pairs ofQuÃ¦sita: Obviously the second head presupposes the first, and is consequent thereupon; while the fourth also presupposes the third. But it might seem a more suitable arrangement (as Themistius and other expositors have conceived) that the third and fourth heads should come first in the list, rather than the first and second; since the third and fourth are simpler, and come earlier in the order of philosophical exposition, while the first and second are more complicated, and cannot be expounded philosophically until afterthe philosophical exposition of the others. This is cleared up by adverting to the distinction, so often insisted on by Aristotle, between what is first in order of cognition relatively to us (nobis notiora), and what is first in order of cognition by nature (naturÃ¢ notiora).To us(that is to men taken individually and in the course of actual growth) the phenomena of nature2present themselves as particulars confused and complicated in every way, with attributes essential and accidental implicated together: we gradually learn first to see and compare them as particulars, next to resolve them into generalities, bundles, classes, and partially to explain theWhyof some by means of others. Here we start from facts embodied in propositions, that include subjects clothed with their attributes. But in theorder of nature(that is, in the order followed by those who know thescibileas a whole, and can expound it scientifically) that which comes first is the Universal or the simple Subject abstracted from its predicates or accompaniments: we have to enquire, first, whether a given subject exists; next, if it does exist, what is its real constituent essence or definition. We thus see the reason for the order in which Aristotle has arranged the two co-ordinate pairs ofQuÃ¦sitaor Problems, conformable to the different processes pursued, on the one hand, by the common intellect, growing and untrained â€” on the other, by the mature or disciplined intellect, already competent for philosophical exposition and applying itself to newincognita.

2Schol.Philopon. p. 241, a. 18-24: τούτων τὸ εἰ ἔστι καὶ τὸ τί ἐστιν εἰσὶν ἁπλᾶ, τὸ δὲ ὅτι καὶ τὸ διότι σύνθετα â€” πρότερα γὰρ ἡμῖν καὶ γνωριμώτερα τὰ σύνθετα, ὡς τῇ φύσει τὰ ἁπλᾶ.Mr. Poste observes upon this quadruple classification by Aristotle (p. 96):â€” â€œThe two last of these are problems of Inductive, but first principles of Deductive, Science; the one being the hypothesis, the other the definition. Theattributeas well as the subject must be defined (I. x.), so that to a certain degree the second problem also is assumed among the principles of Demonstration.â€�

2Schol.Philopon. p. 241, a. 18-24: τούτων τὸ εἰ ἔστι καὶ τὸ τί ἐστιν εἰσὶν ἁπλᾶ, τὸ δὲ ὅτι καὶ τὸ διότι σύνθετα â€” πρότερα γὰρ ἡμῖν καὶ γνωριμώτερα τὰ σύνθετα, ὡς τῇ φύσει τὰ ἁπλᾶ.

Mr. Poste observes upon this quadruple classification by Aristotle (p. 96):â€” â€œThe two last of these are problems of Inductive, but first principles of Deductive, Science; the one being the hypothesis, the other the definition. Theattributeas well as the subject must be defined (I. x.), so that to a certain degree the second problem also is assumed among the principles of Demonstration.â€�

Comparing together these fourQuÃ¦sita, it will appear that in the first and third (QuodandAn), we seek to find out whether there is or is not any middle term. In the second and fourth (CurandQuid), we already know or assume that there is a middle term; and we try to ascertain what that middle term is.3The enquiryCur, is in the main analogous to the enquiryQuid; in both cases, we aim at ascertaining what the cause or middle term is. But, in the enquiryCur, what we discover is perhaps some independent fact or event, which is the cause of the eventquÃ¦situm; while, in the enquiryQuid, what we seek is the realessence or definition of the substance â€” the fundamental, generating, immanent cause of its concomitant attributes. Sometimes, however, theQuidand theCurare only different ways of stating the same thing.E.g.,Quid est eclipsis lunÃ¦? Answer: The essence of an eclipse is a privation of light from the moon, through intervention of the earth between her and the sun.Cur locum habet eclipsis lunÃ¦? Answer: Because the light of the sun is prevented from reaching the moon by intervention of the earth. Here it is manifest that the answers to the enquiriesQuidandCurare really and in substance the same fact, only stated in different phrases.4

3Analyt. Post. II. i. p. 889, b. 37-p. 90, a. 7. συμβαίνει ἄρα ἐν ἁπάσαις ταῖς ζητήσεσι ζητεῖν ἢ εἰ ἔστι μέσον, ἢ τί ἐστι τὸ μέσονÂ· τὸ μὲν γὰρ αἴτιον τὸ μέσον, ἐν ἅπασι δὲ τοῦτο ζητεῖται. Compare Schol. p. 241, b. 10, Br.

4Analyt. Post. II. ii. p. 90, a. 14-23, 31: τὸ τί ἐστιν εἰδέναι ταὐτό ἐστι καὶ διὰ τί ἐστιν.

That thequÃ¦situmin all these researches is a middle term or medium, is plain from those cases wherein the medium is perceivable by sense; for then we neither require nor enter upon research. For example, if we were upon the moon, we should see the earth coming between us and the sun, now and in each particular case of eclipse. Accordingly, after many such observations, we should affirm the universal proposition, that such intervention of the earth was the cause of eclipses; the universal becoming known to us through induction of particular cases.5The middle term, the Cause, theQuid, and theCur, are thus all the same enquiry, in substance; though sometimes suchquÃ¦situmis the quiddity or essential nature of the thing itself (as the essence of a triangle is the cause or ground of its having its three angles equal to two right angles, as well as of its other properties), sometimes it is an extraneous fact.6

5Ibid. a. 24-30. ἐκ γὰρ τοῦ αἰσθέσθαι καὶ τὸ καθόλου ἐγένετο ἂν ἡμῖν εἰδέναιÂ· ἡ μὲν γὰρ αἴσθησις ὅτι νῦν ἀντιφράττειÂ· καὶ γὰρ δῆλον ὅτι νῦν ἐκλείπειÂ· ἐκ δὲ τούτου τὸ καθόλου ἂν ἐγένετο.The purport and relation of this quadruple classification of problems is set forth still more clearly in the sixth book of the Metaphysica (Z. p. 1041) with the explanations of Bonitz, Comm. pp. 358, 359.

The purport and relation of this quadruple classification of problems is set forth still more clearly in the sixth book of the Metaphysica (Z. p. 1041) with the explanations of Bonitz, Comm. pp. 358, 359.

6Analyt. Post. II. ii. p. 90, a. 31.

But how or by what process is thisquÃ¦situmobtained and made clear? Is it by Demonstration or by Definition? What is Definition, and what matters admit of Definition?7Aristotle begins by treating the question dialectically; by setting out a series of doubts and difficulties. First, Is it possible that the same cognition, and in the same relation, can be obtained both by Definition and by Demonstration? No; it is not possible. It is plain that much that is known by Demonstration cannot be known by Definition; for we have seen that conclusions both particular and negative are established by Demonstration (inthe Third and Second figures), while every Definition is universal and affirmative. But we may go farther and say, that even where a conclusion universal and affirmative is established (in the First figure) by Demonstration, that same conclusion can never be known by Definition; for if it could be known by Definition, it might have been known without Demonstration. Now we are assured, by an uncontradicted induction, that this is not the fact; for that which we know by Demonstration is either a proprium of the subjectper se, or an accident or concomitant; but no Definition ever declares either the one or the other: it declares only the essence.8

7Ibid. iii. p. 90, a. 37: τί ἐστιν ὁρισμός, καὶ τίνων, εἴπωμεν, διαπορήσαντες πρῶτον περὶ αὐτῶν.

8Analyt. Post. II. iii. p. 90, b. 13: ἱκανὴ δὲ πίστις καὶ ἐκ τῆς ἐπαγωγῆςÂ· οὐδὲν γὰρ πώποτε ὁρισάμενοι ἔγνωμεν, οὔτε τῶν καθâ€™ αὑτὸ ὑπαρχόντων οὔτε τῶν συμβεβηκότων. ἔτι εἰ ὁ ὁρισμὸς οὐσίας τις γνωρισμός, τὰ γε τοιαῦτα φανερὸν ὅτι οὐκ οὐσίαι.

Again, let us ask,vice versÃ¢, Can everything that is declared by Definition, or indeed anything that is declared by Definition, be known also by Demonstration? Neither is this possible. One and the samecognitumcan be known only by one process of cognition. Definitions are theprincipiafrom which Demonstration departs; and we have already shown that in going back upon demonstrations, we must stop somewhere, and must recognize someprincipiaundemonstrable.9The Definition can never be demonstrated, for it declares only the essence of the subject, and does not predicate anything concerning the subject; whereas Demonstration assumes the essence to be known, and deduces from such assumption an attribute distinct from the essence.10

9Ibid. b. 18-27.

10Ibid. b. 33, seq.: ἔτι πᾶσα ἀπόδειξις τὶ κατά τινος δείκνυσιν, οἷον ὅτι ἔστιν ἢ οὐκ ἔστινÂ· ἐν δὲ τῷ ὁρισμῷ οὐδὲν ἕτερον ἑτέρου κατηγορεῖται, οἷον οὔτε τὸ ζῷον κατὰ τοῦ δίποδος οὐδὲ τοῦτο κατὰ τοῦ ζῷου â€” ὁ μὲν οὖν ὁρισμὸς τί ἐστι δηλοῖ, ἡ δὲ ἀπόδειξις ὅτι ἢ ἔστι τόδε κατὰ τοῦδε ἢ οὐκ ἔστιν.Themistius (p. 71, Speng.) distinguishes the ὁρισμός itself from ἡ πρότασις ἡ τὸν ὁρισμὸν κατηγορούμενον ἔχουσα.

Themistius (p. 71, Speng.) distinguishes the ὁρισμός itself from ἡ πρότασις ἡ τὸν ὁρισμὸν κατηγορούμενον ἔχουσα.

Prosecuting still farther the dialectical and dubitative treatment,11Aristotle now proceeds to suggest, that the Essence (that is, the entire Essence or Quiddity), which is declared by Definition, can never be known by Demonstration. To suppose that it could be so known, would be inconsistent with the conditions of the syllogistic proof used in demonstrating. You prove by syllogism, through a middle term, some predicate or attribute;e.g.because A is predicable of all B, and B is predicable of all C, therefore A is predicable of all C. But you cannot prove, through the middle term B, that A is the essence or quiddityof C, unless by assuming in the premisses that B is the essence of C, and that A is the essence of B; accordingly, that the three propositions, AB, BC, AC, are all co-extensive and reciprocate with each other. Here, then, you have assumed as your premisses two essential propositions, AB, BC, in order to prove as an essential proposition the conclusion AC. But this is inadmissible; for your premisses require demonstration as much as your conclusion. You have committed aPetitio Principii;12you have assumed in your minor premiss the very point to be demonstrated.

11Analyt. Post. II. iv. p. 91, a. 12: ταῦτα μὲν οὖν μέχρι τούτου διηπορήσθω. One would think, by these words, that τὸ διαπορεῖν (or the dubitative treatment) finished here. But the fact is not so: that treatment is continued for four chapters more, to the commencement of ch. viii. p. 93.

12Analyt. Post. II. iv. p. 91, a. 12-32: ταῦτα δâ€™ ἀνάγκη ἀντιστρέφεινÂ· εἰ γὰρ τὸ Α τοῦ Γ ἴδιον, δῆλον ὅτι καὶ τοῦ Β καὶ τοῦτο τοῦ Γ, ὥστε πάντα ἀλλήλων. â€” λαμβάνει οὖν ὃ δεῖ δεῖξαιÂ· καὶ γὰρ τὸ Β ἔστι τί ἐστιν ἄνθρωπος. Themistius, pp. 72, 73: τὸν ἀποδεικνύντα τὸ τί ἦν εἶναι τοῦ ἀνθρώπου, ἄλλο τι δεῖ προλαβεῖν τοῦ αὐτοῦ τὸ τί ἦν εἶναι. â€” οὗ γὰρ βούλεται τὸν ὁρισμὸν ἀποδεῖξαι, τούτου προλαμβάνει τινὰ ὁρισμὸν εἶναι χωτὶς ἀποδείξεως.M. BarthÃ©lemy St. Hilaire, notes, p. 205:â€” â€œIl faut donc, pour conclure par syllogisme que A est la dÃ©finition essentielle de C, que A soit la dÃ©finition essentielle de B, et que B soit lui-mÃªme la dÃ©finition essentielle de C. Mais alors la dÃ©finition de la chose sera dans le moyen terme lui-mÃªme, avant dâ€™Ãªtre dans la conclusion; en effet, la mineure: B est la dÃ©finition essentielle de C, donne la dÃ©finition essentielle de C, sans quâ€™il soit besoin dâ€™allerjusquâ€™Ãla conclusion. Donc la dÃ©monstration de lâ€™essence ainsi entendue est absurde.â€�

M. BarthÃ©lemy St. Hilaire, notes, p. 205:â€” â€œIl faut donc, pour conclure par syllogisme que A est la dÃ©finition essentielle de C, que A soit la dÃ©finition essentielle de B, et que B soit lui-mÃªme la dÃ©finition essentielle de C. Mais alors la dÃ©finition de la chose sera dans le moyen terme lui-mÃªme, avant dâ€™Ãªtre dans la conclusion; en effet, la mineure: B est la dÃ©finition essentielle de C, donne la dÃ©finition essentielle de C, sans quâ€™il soit besoin dâ€™allerjusquâ€™Ãla conclusion. Donc la dÃ©monstration de lâ€™essence ainsi entendue est absurde.â€�

If you cannot obtain Definition as the conclusion of syllogistic Demonstration, still less can you obtain it through the method of generic and specific Division; which last method (as has been already shown in the Analytica Priora) is not equal even to the Syllogism in respect of usefulness and efficacy.13You cannot in this method distinguish between propositions both true and essential, and propositions true but not essential; you never obtain, by asking questions according to the method of generic subdivision, any premisses from which the conclusion follows by necessity. Yet this is what you ought to obtain for the purpose of Demonstration; for you are not allowed to enunciate the full actual conclusion among the premisses, and require assent to it. Division of a genus into its species will often give useful information, as Induction also will;14but neither the one nor the other will be equivalent to a demonstration. A definition obtained only from subdivisions of a genus, may always be challenged, like a syllogism without its middle term.

13Analyt. Post. II. v. p. 91, b. 12, seq.; Analyt. Prior. I. xxxi. p. 46, a. 31. Aristotle here alludes to the method pursued by Plato in the Sophistes and Politicus, though he does not name Plato: ἡ διὰ τῶν διαιρέσεων ὁδός, &c.

14Analyt. Post. II. v. p. 91, b. 15-33: οὐδὲ γὰρ ὁ ἐπάγων ἴσως ἀποδείκνυσιν, ἀλλâ€™ ὅμως δηλοῖ τι. Compare Themistius, p. 74.

Again, neither can you arrive at the definition of a given subject, by assuming in general terms what a definition ought to be, and then declaring a given form of words to be conformable to such assumption; because your minor premiss must involvePetitio Principii. The same logical fault will be committed, if you take your departure from an hypothesis in which you postulate the definition of a certain subject, and then declare inferentially what the definition of its contrary must be. The definition which you here assume requires proof as much as that which you infer from it.15Moreover, neither by this process, nor by that of generic subdivision, can you show any reason why the parts of the definition should coalesce into one essential whole. If they do not thus coalesce â€” if they be nothing better than distinct attributes conjoined in the same subject, likemusicusandgrammaticusâ€” the real essence is not declared, and the definition is not a good one.16

15Analyt. Post. II. vi. p. 92, a. 6-28. Themist. p. 76.Rassow renders ἐξ ὑποθέσεως â€” â€œassumptÃ¢ generali definitionis notione;â€� and also says: â€œτὸ τί ἦν εἶναι â€” generalem definitionis notionem; τὸ τί ἐστιν â€” certam quandam definitionem, significare perspicuum est.â€� (Aristotelis de Notionis Definitione Doctrina, p. 65).

15Analyt. Post. II. vi. p. 92, a. 6-28. Themist. p. 76.

Rassow renders ἐξ ὑποθέσεως â€” â€œassumptÃ¢ generali definitionis notione;â€� and also says: â€œτὸ τί ἦν εἶναι â€” generalem definitionis notionem; τὸ τί ἐστιν â€” certam quandam definitionem, significare perspicuum est.â€� (Aristotelis de Notionis Definitione Doctrina, p. 65).

16Analyt. Post. II. vi. p. 92, a. 32. That the parts of the definition must coalesce into one unity is laid down again in the Metaphysica,Z. pp. 1037, 1038, where Aristotle makes reference to the Analytica as haying already treated the same subject, and professes an intention to complete what has been begun in the Analytica; ἐφâ€™ ὅσον ἐν τοῖς Ἀναλυτικοῖς περὶ ὁρισμοῦ μὴ εἴρηται.

After stating some other additional difficulties which seem to leave the work of Definition inexplicable, Aristotle relinquishes the dubitative treatment, and looks out for some solution of the puzzle: How may it be possible that the Definition shall become known?17He has already told us that to know the essence of a thing is the same as to know the cause or reason of its existence; but we must first begin by knowing that thedefiniendumexists; for there can be no definition of a non-entity, except a mere definition of the word, a nominal or verbal definition. Now sometimes we know the existence of the subject by one or other of its accidental attributes; but this gives us no help towards finding the definition.18Sometimes, however, we obtain a partial knowledge of its essence along with the knowledge of its existence; when we know it along with some constant antecedent, or through some constant, though derivative, consequent. Knowing thus much, we can often discover the cause or fundamental condition thereof, which is the essence or definition ofthe subject.19Indeed, it may happen that the constant derivative, and the fundamental essence on which it depends, become known both together; or, again, the cause or fundamental condition may perhaps not be the essence of the subject alone, but some fact including other subjects also; and this fact may then be stated as a middle term. Thus, in regard to eclipse of the moon, we know the constant phenomenal fact about it, that, on a certain recurrence of the time of full moon, the moon casts no light and makes no shadow. Hence we proceed to search out the cause. Is it interposition of the earth, or conversion of the moonâ€™s body, or extinction of her light, &c.? The new fact when shown, must appear as a middle term, throwing into syllogistic form (in the First figure) the cause or rational explanation of a lunar eclipse; showing not merely that there is an eclipse, but what an eclipse is, or what is its definition.20

17Analyt. Post. II. vii. p. 92, a. 34, seq. The ἀπόριαι continue to the end of ch. vii. He goes on, ch. viii. p. 93, a. 1-2: πάλιν δὲ σκεπτέον τί τούτων λέγεται καλῶς, καὶ τί οὐ καλῶς, &c. â€œTout ce qui prÃ©cÃ¨de ne reprÃ©sente pas la thÃ©orie proprement dite; ce nâ€™est quâ€™une discussion prÃ©liminaireâ€� (Barth. St. Hilaire, not. p. 222). These difficult chapters are well illustrated by Hermann Rassow, ch. i. pp. 9-14.

18Analyt. Post. II. viii. p. 93, a. 3: ἐπεὶ δâ€™ ἐστίν, ὡς ἔφαμεν, ταὐτὸν τὸ εἰδέναι τί ἐστι καὶ τὸ εἰδέναι τὸ αἴτιον τοῦ εἰ ἔστιÂ· Ibid. a. 24: ὅσα μὲν οὖν κατὰ συμβεβηκὸς οἴδαμεν ὅτι ἔστιν, ἀναγκαῖον μηδαμῶς ἔχειν πρὸς τὸ τί ἐστινÂ·οὐδὲγὰρ ὅτι ἔστιν ἴσμενÂ· τὸ δὲ ζητεῖν τί ἐστι μὴ ἔχοντας ὅτι ἔστι, μηδὲν ζητεῖν ἐστίν. καθâ€™ ὅσων δâ€™ ἔχομέν τι, ῥᾷονÂ· ὥστε ὡς ἔχομεν ὅτι ἔστιν, οὕτως ἔχομεν καὶ πρὸς τὸ τί ἐστιν. Compare Brentano, Ueber die Bedeutung des Seienden nach Aristoteles, p. 17.

19Analyt. Post. II. viii. p. 93, a. 21. Themistius, p. 79, Speng.: ὅσα δὲ ἀπὸ τῶν οἰκείων τε καὶ ἐξ αὐτοῦ τοῦ πράγματος, ἀπὸ τούτων ἤδη ῥᾷον εἰς τὸ τί ἐστι μεταβαίνομεν.

20Ibid. p. 93, a. 30-b. 14.

Aristotle has thus shown how the Essence or Quiddity (τί ἐστι) may become known in this class of cases. There is neither syllogism nor demonstration thereof, yet it is declared through syllogism and demonstration: though no demonstration thereof is possible, yet you cannot know it without demonstration, wherever there is an extraneous cause.21

21Ibid. b. 15-20: ὥστε συλλογισμὸς μὲν τοῦ τί ἐστιν οὐ γίνεται οὐδâ€™ ἀπόδειξις, δῆλον μέντοι διὰ συλλογισμοῦ καὶ διâ€™ ἀποδείξεως.Mr. Poste translates an earlier passage (p. 93, a. 5) in this very difficult chapter as follows (p. 107): â€œIf one cause is demonstrable, another indemonstrable cause must be the intermediate; and the proof is in the first figure, and the conclusion affirmative and universal. In this mode of demonstrating the essence, we prove one definition by another, for the intermediate that proves an essence or a peculiar predicate must itself be an essence or a peculiar predicate. Of two definitions, then, one is proved and the other assumed; and, as we said before, this is not a demonstration but a dialectical proof of the essence.â€� Mr. Poste here translates λογικὸς συλλογισμός â€œdialectical proof.â€� I understand it rather as meaning a syllogism, τοῦ ὑπάρχειν simply (Top. I. v. p. 102, b. 5), in which all that you really know is that the predicate belongs to the subject, but in which youassumebesides that it belongs to the subjectessentially. It is not a demonstration because, in order to obtain Essence in the conclusion, you are obliged to postulate Essence in your premiss. (See Alexander ad Topic. I. p. 263, Br.). You have therefore postulated a premiss which required proof as much as the conclusion.

21Ibid. b. 15-20: ὥστε συλλογισμὸς μὲν τοῦ τί ἐστιν οὐ γίνεται οὐδâ€™ ἀπόδειξις, δῆλον μέντοι διὰ συλλογισμοῦ καὶ διâ€™ ἀποδείξεως.

Mr. Poste translates an earlier passage (p. 93, a. 5) in this very difficult chapter as follows (p. 107): â€œIf one cause is demonstrable, another indemonstrable cause must be the intermediate; and the proof is in the first figure, and the conclusion affirmative and universal. In this mode of demonstrating the essence, we prove one definition by another, for the intermediate that proves an essence or a peculiar predicate must itself be an essence or a peculiar predicate. Of two definitions, then, one is proved and the other assumed; and, as we said before, this is not a demonstration but a dialectical proof of the essence.â€� Mr. Poste here translates λογικὸς συλλογισμός â€œdialectical proof.â€� I understand it rather as meaning a syllogism, τοῦ ὑπάρχειν simply (Top. I. v. p. 102, b. 5), in which all that you really know is that the predicate belongs to the subject, but in which youassumebesides that it belongs to the subjectessentially. It is not a demonstration because, in order to obtain Essence in the conclusion, you are obliged to postulate Essence in your premiss. (See Alexander ad Topic. I. p. 263, Br.). You have therefore postulated a premiss which required proof as much as the conclusion.

But the above doctrine will hold only in cases where thereisa distinct or extraneous cause; it will not hold in cases where there is none. It is only in the former (as has been said) that a middle term can be shown; rendering it possible that Quiddity or Essence should be declared by a valid formal syllogism, though it cannot be demonstrated by syllogism. In the latter, where there is no distinct cause, no such middle term can be enunciated: the Quiddity or Essence must be assumed as animmediate or undemonstrable principium, and must be exposed or set out in the best manner practicable as an existent reality, on Induction or on some other authority. The arithmetician makes his first steps by assuming both what a monad is and that there exists such a monad.22

22Analyt. Post. II. ix. p. 93, b. 21. ἔστι δὲ τῶν μὲν ἕτερόν τι αἴτιον, τῶν δâ€™ οὐκ ἔστιν. ὥστε δῆλον ὅτι καὶ τῶν τί ἐστι τὰ μὲν ἄμεσα καὶ ἀρχαί εἰσιν, ἃ καὶ εἶναι καὶ τί ἐστιν ὑποθέσθαι δεῖ ἢ ἄλλον τρόπον φανερὰ ποιῆσαι. ὅπερ ὁ ἀριθμητικὸς ποιεῖÂ· καὶ γὰρ τί ἐστι τὴν μονάδα ὑποτίθεται, καὶ ὅτι ἔστιν.Themistius, p. 80: ἃ καὶ εἶναι καὶ τί ἐστιν ὑποθέσθαι δεῖ, ἢ ἄλλον τρόπον φανερὰ ποιῆσαι ἐξ ἐπαγωγῆς ἢ πίστεως ἢ ἐμπειρίας. Rassow, De Notionis Definitione, pp. 18-22.

Themistius, p. 80: ἃ καὶ εἶναι καὶ τί ἐστιν ὑποθέσθαι δεῖ, ἢ ἄλλον τρόπον φανερὰ ποιῆσαι ἐξ ἐπαγωγῆς ἢ πίστεως ἢ ἐμπειρίας. Rassow, De Notionis Definitione, pp. 18-22.

We may distinguish three varieties of Definition. 1. Sometimes it is the mere explanation what a word signifies; in this sense, it has nothing to do with essence or existence; it is a nominal definition and nothing more.232. Sometimes it enunciates the Essence, cause, or reason of thedefinitum; this will happen where the cause is distinct or extraneous, and where there is accordingly an intervening middle term: the definition will then differ from a demonstration only by condensing into one enunciation the two premisses and the conclusion which together constitute the demonstration.243. Sometimes it is an immediate proposition, an indemonstrable hypothesis, assuming Essence or Quiddity; the essence itself being cause, and no extraneous cause â€” no intervening middle term â€” being obtainable.25

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