6 ideas
Hellenistic ethical argument is judged the way medicine is judged, by whether it cures the patient and not only by its logical elegance. Each school starts from a diagnosis of what makes human life miserable, gives an account of what health for the soul looks like, and then designs its arguments as treatments fitted to the patient's particular condition.
Emotions like fear, anger and grief are not blind urges. They are built from beliefs, or amount to beliefs, about what matters and what is at stake. Because they rest on judgments, argument can reach and reshape them, which is the only reason a talking cure for the passions is possible at all.
Much human suffering comes from beliefs absorbed from culture, such as fear of death, the craving for wealth and status, and romantic obsession. These beliefs feel natural but were taught. Seeing them as a socially transmitted illness moves therapy away from managing symptoms and toward uprooting the beliefs, which may be held below conscious awareness.
The fictional student Nikidion shows that a therapeutic argument works on a particular person with particular ailments. So the same argument can be good medicine for one person and useless for another. Repetition, memorization, vivid examples and a personal relationship with the teacher all count as legitimate tools, because the goal is lasting change in belief and not just assent in the moment.
When argument is valued only for its curative effect, the teacher may use any belief that helps, whether or not it is true. The student can end up dependent on the master's authority instead of thinking critically. The Epicurean and Sceptical approaches run this risk more than the Stoics, who insist that the patient become a fully rational agent.
Removing vulnerability to grief, anger and fear requires withdrawing value from external things like people, city and body that luck can take away. The Stoic goal of freedom from passion would therefore also wipe out deep attachment and the moral seriousness it carries. That makes the cure's price a real philosophical objection, not a side effect.