§2.2.7Πῶς οὖν δὴ ὁ ὁριζόμενος δείξει τὴν οὐσίαν ἢ τὸ τί ἐστιν;
How then indeed will the definer show the substance or 'what it is'?
οὔτε γὰρ ὡς ἀποδεικνὺς ἐξ ὁμολογουμένων εἶναι δῆλον ποιήσει ὅτι ἀνάγκη ἐκείνων ὄντων ἕτερόν τι εἶναι (ἀπόδειξις γὰρ τοῦτο), οὄθʼ ὡς ὁ ἐπάγων διὰ τῶν· καθʼ ἕκαστα δήλων ὄντων, ὅτι πᾶν οὕτοὡς τῷ μηδὲν ἄλλως· οὐ γὰρ τί ἐστι δείκνυσιν, ἀλλʼ ὅτι ἢ ἔστιν ἢ οὐκ ἔστιν.
For he will not make it clear, like the one who demonstrates from agreed premises, that since those are, something else must exist (for this is demonstration), nor like the one who induces through individual clear cases, that everything is so because nothing is otherwise; for induction does not show 'what it is', but that something is or is not.
τίς οὖν ἄλλος τρόπος λοιπός;
What other way, then, is left?
οὐ γὰρ δὴ δείξει γε τῇ αἰσθήσει ἢ τῷ δακτύλῳ.
For surely he will not show it by perception or by the finger.
Ἔτι πῶς δείξει τὸ τί ἐστιν;
Furthermore, how will he show 'what it is'?
ἀνάγκη γὰρ τὸν εἰδότα τὸ τί ἐστιν ἄνθρωπος ἢ ἄλλο ὁτιοῦν, εἰδέναι καὶ ὅτι ἔστιν (τὸ γὰρ μὴ ὂν οὐδεὶς οἶδεν ὅ τι ἐστίν, ἀλλὰ τί μὲν σημαίνει ὁ λόγος ἢ τὸ ὄνομα, ὅταν εἴπω τραγέλαφος, τί δʼ ἐστὶ τραγέλαφος ἀδύνατον εἰδέναι).
For it is necessary that the one who knows 'what man is' or what anything else is, also knows that it exists (for no one knows what a non-existent thing is, but rather what the account or the name signifies when I say 'tragelaphos' (goat-stag), but it is impossible to know what a tragelaphos is).
ἀλλὰ μὴν εἰ δείξει τί ἐστι καὶ ὅτι ἕστι, πῶς τῷ αὐτῷ λόγῳ δείξει;
But indeed, if he is to show what it is and that it exists, how will he show them by the same account?
ὅ τε γὰρ ὁρισμὸς ἕν τι δηλοῖ καὶ ἡ ἀπόδειξις· τὸ δὲ τί ἐστιν ἄνθρωπος καὶ τὸ εἶναι ἄνθρωπον ἄλλο.
For both definition and demonstration make one thing clear; but what a man is and for man to be are different.
Εἶτα καὶ διʼ ἀποδείξεώς φαμεν ἀναγκαῖον εἶναι δείκνυσθαι ἅπαν ὅ τι ἐστίν, εἰ μὴ οὐσία εἴη.
Next, we also say that it is necessary that everything that is, unless it be a substance, is demonstrated to exist.
τὸ δʼ εἶναι οὐκ οὐσία οὐδενί οὐ γὰρ γένος τὸ ὄν.
But to be is not the substance of anything; for being is not a genus.
ἀπόδειξις ἄρʼ ἔσται ὅτι ἔστιν.
There will therefore be a demonstration that it exists.
ὅπερ καὶ νῦν ποιοῦσιν αἱ ἐπιστῆμαι. τί μὲν γὰρ σημαί· νει τὸ τρίγωνον, ἔλαβεν ὁ γεωμέτρης, ὅτι δʼ ἔστι, δείκνυσιν.
Which is indeed what the sciences do now; for what the triangle signifies, the geometer assumes, but that it exists, he demonstrates.
τί οὖν δείξει ὁ ὁριζόμενος ἢ τί ἐστι τὸ τρίγωνον;
What then will the definer show except what the triangle is?
εἰδὼς ἄρα τις ὁρισμῷ τί ἐστιν, εἰ ἔστιν οὐκ εἴσεται.
Thus, someone knowing by definition what it is, will not know if it exists.
ἀλλʼ ἀδύνατον.
But that is impossible.
Φανερὸν δὲ καὶ κατὰ τούς νῦν τρόπους τῶν ὅρων ὡς οὐ δεικνύουσιν οἱ ὁριζόμενοι ὅτι ἔστιν.
It is also manifest, even according to the current ways of definitions, that definers do not show that it exists.
εἰ γὰρ καὶ ἕστιν ἐκ τοῦ μέσου τι ἴσον, ἀλλὰ διὰ τί ἔστι τὸ ὁρισθέν;
For even if there is something equal from the center, yet why does the defined thing exist?
καὶ διὰ τί τοῦτʼ ἔστι κύκλος;
And why is this a circle?
εἴη γὰρ ἄν καὶ ὀρειχάλκου φάναι εἶναι αὐτόν.
For one could say that it is the definition of bronze.
οὔτε γὰρ ὅτι δυνατὸν εἶναι τὸ λεγόμενον προσδηλοῦσιν οἱ ὅροι, οὔτε ὅτι ἐκεῖνο οὗ φασὶν εἶναι ὁρισμοί, ἀλλʼ ἀεὶ ἔξεστι λέγειν τὸ διὰ τί.
For definitions do not additionally make clear that what is said is possible, nor that it is that of which they claim to be definitions, but it is always possible to ask 'why?'.
Εἰ ἄρα ὁ ὁριόμενος δείκνυσιν ἢ τί ἐστιν ἢ τί σημαίνει τούνομα, εἰ μὴ ἔστι μηδαμῶς τοῦ τί ἐστιν, εἴη ἄν ὁ ὁρισμός λόγος ὀνόματι τὸ αὐτὸ σημαίνων.
If, then, the definer shows either what it is or what the name signifies, and if there is in no way any showing of 'what it is', then definition would be an account signifying the same thing as a name.
ἀλλʼ ἄτοπον.
But this is absurd.
πρῶτον μὲν γὰρ καὶ μὴ οὐσιῶν ἄν εἴη καὶ τῶν μὴ ὄντων· σημαίνειν γὰρ ἔστι καὶ τὰ μὴ ὄντα.
For first, there would be definitions of non-substances and of non-existent things; for it is possible to signify even non-existent things.
ἔτι πάντες οἱ λόγοι ὁρισμοὶ ὄαν εἶεν· εἴη γὰρ ἄν ὄνομμα θέσθαι ὁποιῳοῦν λόγῳ, ὥστε ὅρους ἄν διαλεγομεθα πάντες καὶ ἡ Ἰλιὰς ὁρισμὸς ἄν εἴη.
Furthermore, all accounts would be definitions; for it would be possible to assign a name to any account whatsoever, so that we would all be conversing in definitions and the 'Iliad' would be a definition.
ὅτι οὐδεμία ἀπόδειξις ἀποδείξειεν ἄν ὅτι τοῦτο τοὔνομα τουτὶ δηλοῖ· οὐδʼ οἱ ὁρισμοὶ τοίνυν τοῦτο προσδηλοῦσιν.
Moreover, no demonstration could demonstrate that this name clarifies this thing; hence, neither do definitions additionally show this.
Ἐκ μὲν τοίνυν τούτων οὔτε ὁρισμός καὶ συλλογισμός φαίνεται ταὐτὸν ὄν, οὔτε ταὐτοῦ συλλογισμός καὶ ὁρισμός· τπρός δὲ τούτοις, ὅτι οὔτε ὁ ὁρισμός οὐδὲν οὔτε ἀποδείκνυσιν οὔτε δείκνυσιν, οὔτε τὸτίέστιν οὐθʼ ὁρισμῷ οὔτʼ ἀποδείξει ἔστι γνῶναι.
From these things, therefore, it appears neither that definition and syllogism are the same, nor that there is syllogism and definition of the same thing; and in addition to these, that definition neither demonstrates nor shows anything, and that 'what it is' can be known neither by definition nor by demonstration.