Rival Lovers
 The rival erastai of the title are a devotee of wrestling and athletics, who disparages philosophy as shameful nonsense, and a young man who cultivates mousikē (a term embracing music, poetry, and philosophy). As the dialogue opens, they are quarrelling, at a grammarian's school in the presence of the boy they love and of other boys and young men, over the question whether philosophizing is noble and admirable (kalon). Socrates inserts himself into the quarrel. When he begins by questioning the musical rival's claim to know what philosophizing is, he gets the answer that philosophy is polymathy. With the help of the athletic rival, who knows that the good of exercise depends on being done in the right amount (not the maximum amount), Socrates points out that the same is true of most good things, and turns to asking what kind of things the one who philosophizes (loves wisdom) ought to learn, if the object is not simply to know all or many things (135a). The musical rival suggests that the philosopher, while not needing to bother himself with the hands-on practicalities (cheirourgia, 135b), should aspire to a level of understanding in all the arts (technai) such that he is second only to the expert in that particular field—still a kind of polymathy. Socrates challenges this suggestion by forcing the would-be philosopher to admit that, in any conceivable particular circumstance, the philosopher would be useless in comparison to a true expert on the matter (e.g., a physician or a ship's pilot). Accordingly, Socrates develops an alternative account of the philosopher's proper interest, based on the premise that goodness (which the interlocutors have agreed in ascribing to philosophy) depends critically on the knowledge how to make good and to tell good from bad, which is also the knowledge needed to deal out punishments. This knowledge, the musical rival agrees, is the knowledge of the one who serves as judge (hē dikastikē epistēmē, 137d). Socrates goes on to argue that this knowledge can be identified with justice, self-control, and self-knowledge, and with the arts practiced by the statesman, the king (or tyrant), and the head of a household (or master). The conclusion is that these are all in fact just one art (138c), one of paramount importance, in which the philosopher must be supreme. When Socrates first met the rival lovers, he put little hope in conversation with the athletics enthusiast, who professed experience "in deeds (erga) and not in words (logoi)" (132d). But at the end he wins the crowd's applause by having shut up the "wiser" young man, so that it is the athletic rival who agrees with Socrates' conclusions (139a). The entire story of the discussion is told in the first person by Socrates, without any interruption or indication what audience he addresses. At just over seven Stephanus pages, Rival Lovers is one of the shortest dialogues in the Thrasyllan canon of Plato's works (about the same length as Hipparchus, with only Clitophon being shorter).