ἢ ἐλευθέρῳ διάγειν τῷ τοιούτῳ τὸν βίον ἐστὶν ἄρα
anything special about this ἄρα? Can we translate it as ‘therefore’?
It’s completing the argument. He’s said that for someone who doesn’t know how to use his soul it’s better not to live; but if he must live, then (ἄρα) better to live a slave than free. It’s inferential, but weaker than “therefore.”