Charging and paying for it

Here is a good argument to show why it is important to charge for philosophical discussions and also also important to pay for a bit of philosophical teaching.  Antiphon attacks Socrates with this dilemma (Xen. Mem. 1.16.11-12, Marchant's translation):

πάλιν δέ ποτε ὁ Ἀντιφῶν διαλεγόμενος τῷ Σωκράτει εἶπεν: ὦ Σώκρατες, ἐγώ τοί σε δίκαιον μὲν νομίζω, σοφὸν δὲ οὐδ᾽ ὁπωστιοῦν: δοκεῖς δέ μοι καὶ αὐτὸς τοῦτο γιγνώσκειν: οὐδένα γοῦν τῆς συνουσίας ἀργύριον πράττῃ. καίτοι τό γε ἱμάτιον ἢ τὴν οἰκίαν ἢ ἄλλο τι ὧν κέκτησαι νομίζων ἀργυρίου ἄξιον εἶναι οὐδενὶ ἂν μὴ ὅτι προῖκα δοίης, ἀλλ᾽ οὐδ᾽ ἔλαττον τῆς ἀξίας λαβών. [12] δῆλον δὴ ὅτι εἰ καὶ τὴν συνουσίαν ᾤου τινὸς ἀξίαν εἶναι, καὶ ταύτης ἂν οὐκ ἔλαττον τῆς ἀξίας ἀργύριον ἐπράττου. δίκαιος μὲν οὖν ἂν εἴης, ὅτι οὐκ ἐξαπατᾷς ἐπὶ πλεονεξίᾳ, σοφὸς δὲ οὐκ ἄν, μηδενός γε ἄξια ἐπιστάμενος.

“Socrates, I for my part believe you to be a just, but by no means a wise man. And I think you realise it yourself. Anyhow, you decline to take money for your society. Yet if you believed your cloak or house or anything you possess to be worth money, you would not part with it for nothing or even for less than its value. Clearly, then, if you set any value on your society, you would insist on getting the proper price for that too. It may well be that you are a just man because you do not cheat people through avarice; but wise you cannot be, since your knowledge is not worth anything.”

If Socrates is honest then since he does not charge for a chat  it must be that he does not consider his conversation to be worth anything. But in that case, if Socrates is honest then he cannot be wise. If he is wise and his conversation is worth something, then he is not honest because he does not charge for it. Socrates is therefore either wise or honest, but cannot be both.

Someone dishing out a bit of philosophy for free is either an idiot or is dishonest. And you wouldn't want to learn philosophy from an idiot. And it's unsettling to learn it from someone who is dishonest about its value.  (Socrates replies in 1.16.13 that just as there are right and wrong ways to go about bestowing beauty, so too there are honourable and shameful ways to dish out wisdom.  It's pretty seedy to sell one's beauty even if its rightly thought to be something valuable; so too it's a dirty business to sell wisdom.)