Daf Yomi Gittin 21a/23a: Does Rabbi Yochanan Contradict Himself?

Translation taken from my Rif Yomi blog:

{Gittin 21b}
Mishna:

אין כותבין במחובר לקרקע
כתבו על המחובר תלשו וחתמו ונתנו לה כשר
ר' יהודה פוסל עד שתהא כתיבתו וחתימתו בתלוש
רבי יהודה בן בתירה אומר אין כותבין לא על נייר מחוק ולא על הדיפתרא מפני שהוא יכול להזדייף
וחכמים מכשירין

[A GET] MUST NOT BE WRITTEN ON SOMETHING STILL ATTACHED TO THE SOIL.
IF, HOWEVER, IT WAS WRITTEN ON SOMETHING STILL ATTACHED TO THE SOIL AND THEN DETACHED AND SIGNED AND GIVEN TO THE WIFE, IT IS VALID.
RABBI YEHUDA DECLARES IT INVALID UNLESS IT IS BOTH WRITTEN AND SIGNED ON SOMETHING NOT ATTACHED TO THE SOIL.
RABBI YEHUDA BEN BETEIRA SAYS THAT [A GET] MUST NOT BE WRITTEN ON A SHEET FROM WHICH WRITING HAS BEEN ERASED, NOR ON DIFTERA {=a certain kind of skin}, BECAUSE WRITING ON IT CAN BE ALTERED [WITHOUT BEING NOTICEABLE].
THE SAGES, HOWEVER, DECLARE SUCH A GET VALID.

Gemara:
כתבו על המחובר
והא אמרת רישא אין כותבין
אמר רב יהודה אמר שמואל והוא ששייר מקום התורף
וכן אמר רבה בר בר חנה אמר רבי יוחנן והוא ששייר מקום התורף
ורבי אלעזר היא דאמר עידי מסירה כרתי
והכי קאמר אין כותבין טופס במחובר גזירה שמא יכתוב תורף כתבו לטופס ותלשו וכתבו לתורף ונתנו לה כשר:

"IF IT WAS WRITTEN ON SOMETHING STILL ATTACHED TO THE SOIL":
But the resha {in the preceding statement} said that we do not write!
Rav Yehuda cited Shmuel: And this was where he left the place of the toref {which consists of their names, the date, and the words harei at muteres lechol adam, such that this would be filled in once detached}.
And so did Rabba bar bar Chana cite Rabbi Yochanan: And this is where he left the place of the toref.
And it is Rabbi Eleazar, who maintains that witnesses to the handing over are what effects it. And this is what it means to say: We do not write the tofes {the main, standard, part of the get} upon what is attached, as a decree lest he write the toref {on attached as well}. If he wrote the tofes and separated it, and then wrote the toref and gave it to her, it is valid.

A point worthy of consideration is that despite this statement attributed to Rabbi Yochanan here in Bavli, it would seem in Yerushalmi that the Mishna is in disagreement with Rabbi Yochanan, and possibly that Rabbi Yochanan should not be the one to advance what he advances here. And compare with Rabbi Shimon ben Lakish, here (in the continuation of the gemara, not given above, that what is missing is the signatures, and that is what the gezeira is for -- see inside) and there.

That gemara, Yerushalmi Gittin 14a, states:

דף יג, א פרק ב הלכה ד משנה אין כותבין במחובר לקרקע כתבו במחובר תלשו וחתמו ונתנו לה כשר ור' יהודה פוסל עד שתהא כתובתו וחתימתו בתלוש ר' יהודה בן בתירה אומר אין כותבין לא על הנייר המחוק ולא על הדיפתרא מפני שהוא יכול להזדייף וחכמים מכשירין:
דף יג, א פרק ב הלכה ד גמרא לית הא פליגא על רבי יוחנן דר' יוחנן אמר כתב תרפו בטופס כשר. ר"ל אמר אם כתב תרפו בטופס פסול.

To understand what this gemara means, and to see three different interpretations and approaches (that of Pnei Moshe, Korban HaEdah, and Ridvaz), click on this link to the Yerushalmi Gittin over at HebrewBooks.org. The link will take you directly to the correct page.

The correct resolution to this (at least so far -- I still have what to grapple with) is that this is indeed a contradiction to Rabbi Yochanan in Yerushalmi, but that we are relying here in Bavli on another Amora who is citing Rabbi Yochanan. And thus the apparent contradiction. Indeed, a bit later, in Gittin 23a, a gemara on another Mishna, this point is made explicitly, when Rav Zerika cites Rabbi Yochanan as going against Shmuel, and arguing against the Mishna, saying that it is not Torah, and that it is Rabbi Meir rather than Rabbi Eliezer -- and this is contrasted with the statement attributed to Rabbi Yochanan earlier in our gemara.

Rab Judah said in the name of Samuel that [a deaf-mute etc. is qualified to write] only if he leaves the formal part a blank. So too said R. Haga in the name of 'Ulla: [A deaf-mute etc. is qualified to write] only if he leaves the formal part a blank. [The Mishnah thus] follows R. Eleazar. R. Zerika, however, said in the name of R. Johanan: This is not Torah. What does he mean by saying, 'This is not Torah'? — Said R. Abba: Here [the Mishnah] makes known to us that there is no force in [the ruling that the Get should be written with] 'special intention', and it follows the view of R. Meir who said that it is the signatures of the witnesses which make [the Get] effective. But did not Rabba b. Bar Hana say in the name of R. Johanan that [the Mishnah] follows Rabbi Eleazar? — Two Amoraim report R. Johanan differently.

Now, once we have the Yerushalmi in accordance with the R' Zerika's attributed statement of Rabbi Yochanan, it would seem that he is correct, and that indeed, the Mishna argues on Rabbi Yochanan.