The Gemara on our daf quotes a baraita that teaches:
- If someone calls another person an eved, he is ostracized.
- If one calls another a mamzer, he is sofeg et ha-arba’im – liable to receive forty lashes.
- If one calls another a rasha, yored imo le-hayyav – the insulted person can harass the accuser in all aspects of his life (i.e., the courts will not respond, but the individual who has been targeted as a rasha can take matters into his own hands).
Rav Shmuel ben Hofni Gaon was asked why the different epithets receive such different punishments, and he answered that these were simply edicts that could not be explained. Rav Se’adya ibn Danan responded to this by arguing that such an explanation might be appropriate when dealing with a difficult-to-explain biblical law, but when discussing a rabbinic ordinance, there must be a logical explanation for their ruling.
He suggests that each of these punishments fits the crime midah ke-neged midah – each in an appropriate fashion.
When someone calls his friend a slave, he is attempting to remove him from the Jewish community by means of his accusation. In response he himself is ostracized, which effectively removes the accuser from interaction with the community.
When someone calls his friend a mamzer, he is not impugning his Jewishness, but he is attempting to injure him personally, since, according to Jewish law, a mamzer is very limited in the people who he can marry. Therefore we punish the accuser personally by giving him malkot.
If someone calls his friend a rasha, that causes the slandered to lose the sympathy of others. In response we show no mercy on the accuser and allow the accused to harass him.