§2.1.13#1Τὸ δʼ ὅτι διαφέρει καὶ τὸ διότι ἐπίστασθαι, πρῶτον μὲν ἐν τῇ αὐτῇ ἐπιστήμῃ, καὶ ἐν ταύτῃ διχῶς, ἕνα μὲν τρόπον ἐὰν μὴ διʼ ἀμέσων γίνηται ὁ συλλογισμός (οὐ γὰρ λαμβάνεται τὸ πρῶτον αἴτιον, ἡ δὲ τοῦ διότι ἐπιστήμη κατὰ τὸ πρῶτον αἴτιον), ἄλλον δὲ εἰ διʼ ἀμέσων μέν, ἀλλὰ μὴ διὰ τοῦ αἰτίου ἀλλὰ τῶν ἀντιστρεφόντων διὰ τοῦ γνωριμωτέρου.
To know that a thing is and to know why it is differ. First, within the same science, and in this in two ways: in one way, if the syllogism does not come about through immediate premises (for the primary cause is not assumed, whereas science of the reason why is according to the primary cause); in another way, if it is indeed through immediate premises, but not through the cause, but through that of the converting terms which is more known.
κωλύει γὰρ οὐδὲν τῶν ἀντικατηγορουμένων γνωριμώτερον εἶναι ἐνίοτε τὸ μὴ αἴτιον, ὥστʼ ἔσται διὰ τούτου ἡ ἀπόδειξις, οἷον ὅτι ἐγγὺς οἱ πλάνητες διὰ τοῦ μὴ στίλβειν.
For nothing prevents the non-cause among counter-predicated terms from being sometimes more known, so that the demonstration will be through this; for example, that the planets are near through their not twinkling.
ἔστω ἐφʼ Γ πλάνητες. ἐφʼ ᾧ Β τὸ μὴ στίλβειν, ἐφʼ ᾧ Α τὸ ἐγγὺς εἶναι.
Let C be the planets, B not twinkling, A being near.
ἀληθὲς δὴ τὸ Β κατὰ τοῦ Γ εἰπεῖν· οἱ γὰρ πλάνητες οὐ στίλβουσιν.
It is true, then, to state B of C; for the planets do not twinkle.
ἀλλὰ καὶ τὸ Α κατὰ τοῦ Β· τὸ γὰρ μὴ στίλβον ἐγγύς ἐστι· τοῦτο δʼ εἰλήφθω διʼ ἐπαγωγῆς ἢ διʼ αἰσθήσεως.
But also A of B; for that which does not twinkle is near—let this be assumed through induction or sensation.
ἀνάγκη οὖν τὸ Α τῷ Γ ὑπάρχειν, ὥστʼ ἀποδέδεικται ὅτι οἱ πλάνητες ἐγγύς εἰσιν.
It is necessary, therefore, for A to belong to C, so that it has been demonstrated that the planets are near.
οὗτος οὖν ὁ συλλογισμὸς οὐ τοῦ διότι ἀλλὰ τοῦ ὅτι ἐστίν· οὐ γὰρ διὰ τὸ μὴ στίλβειν ἐγγύς εἰσιν, ἀλλὰ διὰ τὸ ἐγγὺς εἶναι οὐ στίλβουσιν.
This syllogism, then, is not of the reason why but of the fact; for they are not near because they do not twinkle, but they do not twinkle because they are near.
ἐγχωρεῖ δὲ καὶ διὰ θατέρου θάτερον δειχθῆναι, καὶ ἔσται τοῦ διότι ἡ ἀπόδειξις, οἷον ἔστω τὸ Γ πλάνητες, ἐφʼ ᾧ Β τὸ ἐγγὺς εἶναι, τὸ Α τὸ μὴ στίλβειν· ὑπάρχει δὴ καὶ τὸ 78b Β τῳ Γ καὶ τὸ Α τῳ Β, ὥστε καὶ τῷ Γ τὸ Α.
But it is also possible to demonstrate the one through the other, and the demonstration will be of the reason why; for example, let C be the planets, B being near, A not twinkling; then B belongs to C and A to B, so that A also belongs to C.
καὶ ἔστι τοῦ διότι ὁ συλλογισμός· εἴληπται γὰρ τὸ πρῶτον αἴτιον.
And the syllogism is of the reason why; for the primary cause has been assumed.
πάλιν ὡς τὴν σελήντην δεικνύουσιν ὅτι σφαιροειδής, διὰ τῶν αὐξήσεων—εἰ γὰρ τὸ αὐξανόμενον οὕτω σφαιροειδές, αὐξάνει δʼ ἡ σελήνη, φανερὸν ὅτι σφαιροειδής—οὕτω μὲν οὖν τοῦ ὅτι γέγονεν ὁ συλλογισμός, ἀνάπαλιν δὲ τεθέντος· τοῦ μέσου τοῦ διότι· οὐ γὰρ διὰ τὰς αὐξήσεις σφαιροειδής ἐστιν, ἀλλὰ διὰ τὸ σφαιροειδὴς εἶναι λαμβάνει τὰς αὐξήσεις τοιαύτας.
Again, as they demonstrate that the moon is spherical through its waxing—for if that which waxes in this way is spherical, and the moon waxes, it is clear that it is spherical—in this way, then, the syllogism of the fact is formed, but if the terms are placed conversely, the middle term being the reason why, the syllogism is of the reason why; for it is not spherical because of its waxing, but because it is spherical it takes such waxings.
σελήντη ἐφʼ ᾧ Γ, σφαιροειδὴς ἐφʼ ᾧ Β. αὔξησις ἐφʼ ὧ Α. ἐφʼ ὧν δὲ τὰ μέσα μὴ ἀντιστρέφει καὶ ἔστι γνωριμώτερον τὸ ἀναίτιον, τὸ ὅτι μὲν δείκνυται, τὸ διότι δʼ οὔ.
Let moon be C, spherical be B, waxing be A. But in cases where the middle terms do not convert and the non-cause is more known, the fact is demonstrated, but not the reason why.
Ἔτι ἐφʼ ὧν τὸ μέσον ἔξω τίθεται.
Further, in cases where the middle term is placed outside.
καὶ γὰρ ἐν τούτοις τοῦ ὅτι καὶ οὐ τοῦ διότι ἡ ἀπόδειξις· οὐ γὰρ λέγεται τὸ αἴτιον.
For in these too the demonstration is of the fact and not of the reason why; for the cause is not stated.
οἷον διὰ τί οὐκ ἀναπνεῖ ὁ τοῖχος;
For example, why does a wall not breathe?
ὅτι οὐ ζῷον.
Because it is not an animal.