QUESTION: The Gemara quotes a Beraisa which teaches that a Kohen who has a wart may not remove it by himself on Shabbos, even if he needs to remove it in order to perform the Avodah in the Beis ha'Mikdash. Rather, he must have his friend remove it for him, so that only a Melachah d'Rabanan will be done. (To remove one's own wart involves the Melachah d'Oraisa of Gozez, shearing, on Shabbos.) Moreover, his friend may not remove the wart directly with his hands. Rather, he must remove it with a "Shinuy" (in an unusual manner) by biting it off with his teeth. This is necessary in order to distance himself even further from the possibility of the transgression of a Melachah d'Oraisa.
The Gemara asserts that the author of this Beraisa must be Rebbi Eliezer. He maintains that one is required to utilize every feasible Shinuy in order to distance himself as much as possible from a Melachah d'Oraisa. The Rabanan, in contrast, do not require such an abundance of Shinuyim. According to the Rabanan, the Kohen's friend may remove the wart with his hands.
The Gemara here assumes that Rebbi Eliezer is more stringent than the Rabanan with regard to what acts a Kohen may do on Shabbos in order to prepare to serve in the Beis ha'Mikdash. However, the Gemara earlier (103a) teaches that Rebbi Eliezer proposed significant leniencies with regard to a Kohen who serves in the Beis ha'Mikdash. For example, Rebbi Eliezer permits a Kohen to transgress an Isur d'Oraisa while he prepares himself for the Avodah. (In contrast, the Rabanan only allow the Kohen to transgress an Isur d'Rabanan.)
Rebbi Eliezer does not permit the Kohen to commit a Melachah d'Oraisa when he is able to use a Shinuy and avoid the transgression. However, it is not clear why, in the case of a Kohen who needs to remove a wart, Rebbi Eliezer is more stringent than the Rabanan and requires a double-Shinuy.
(a) TOSFOS (DH Iy Amart) cites the SAR MI'KUTZI who explains that it is because Rebbi Eliezer is normally so lenient that he adopts an especially stringent position in the case of the wart.
Since Rebbi Eliezer normally allows a Melachah d'Oraisa to be done for the sake of the Avodah in the Beis ha'Mikdash, he is concerned that when it is prohibited (such as when the act can be done with a Shinuy), the Kohen will, out of habit, perform a Melachah d'Oraisa as he normally does. Therefore, when a Shinuy is required, Rebbi Eliezer rules that the Kohen should use as many Shinuyim as possible. The Rabanan, who never allow a Melachah d'Oraisa, have no such concern. A single Shinuy suffices, since there is no reason to suspect that one will make a mistake and think that a Melachah d'Oraisa may be done.
(b) The TOSFOS HA'ROSH suggests another explanation. There is a separate issue in the case of the removal of the wart which is cause for Rebbi Eliezer's stringency.
As RASHI explains (DH b'Shinav), the Gemara in Shabbos (94b) teaches that, according to the Rabanan, a person who removes a wart from his body on Shabbos with his own hands or teeth does not transgress a Torah prohibition. According to Rebbi Eliezer, though, he does transgress a Torah prohibition. In addition, Rebbi Eliezer and the Rabanan agree that to remove a wart with a utensil is prohibited, even if another person wields the utensil. (This is evident from the Gemara's statement that Rebbi Eliezer "Gazar Yad (Chaveiro) Atu Kli.")
Consequently, according to the Rabanan who maintain that there is no Melachah involved when one removes his own wart, a person should be permitted to remove his wart by himself (albeit with his teeth) in preparation for the Avodah. Having a friend remove it for him should not be considered a Shinuy at all, since the Halachah does not distinguish between one who removes his own wart and one who removes another person's wart. (In both cases, no Melachah is done if the wart is removed with hands or teeth, but a Melachah is done if a utensil is used.) According to Rebbi Eliezer, who maintains that the removal of one's own wart by hand or tooth is a Melachah d'Oraisa, when a friend destroys the wart, it is considered an appropriate Shinuy, for it avoids a Melachah d'Oraisa.
(It is important to note that the simple understanding of the Gemara here is that, according to the Rabanan, "the wart should be removed by hand." According to the way the Tosfos ha'Rosh explains the Gemara, however, the Gemara's main point is that, according to the Rabanan, the Kohen should remove his wart by himself. Accordingly, the Gemara does not state its main argument explicitly, but rather it leaves it to be inferred logically.)