I often hear that the printed "Rashi" commentary in certain masechtot of the Talmud Bavli (first that come to mind are Moed Katan and Nedarim) is not actually written by Rashi. Does anyone have a full list of which of the commentaries were actually written by Rabbi Shlomo Yitzchaki and which were written by others in his style? How would one tell the difference?
According to the JNUL website,
Printed editions of the commentaries on tractates Ta’anit, Nedarim, Nazir and Horayot have been mistakenly attributed to him, and were most probably written by the scholars of Mainz or others. Likewise the printed commentary on Moed Katan is wrongly attributed to him. Two tractates have partial Rashi commentaries: Bava Batra (until 29b) and Makkot (until 20a). There is some conjecture as to whether Rashi was the author of the commentary on the Tractate Avot printed in the Siddur Tefila (daily prayerbook), edited by Netanel ben Peretz Halfan, Trino, 1525.
As to how one would be able to tell the difference, I assume it is through normal literary analysis methods, such as style of writing, linguistics, access (or lack thereof) to certain other texts quoted within, reconciliation with author's other writings, etc.
In some cases it is brutally obvious -- pseudo-Rashi on Tamid, for example, cites Rashi on Shabbat by name. In others it's more difficult to tell. A few tools -- pseudo-Rashi occasionally cites different foreign languages, or the same ones (French, German/Yiddish) at different frequencies. pseudo-Rashi occasionally explicitly disagrees with genuine Rashi on other sugyos. An experienced reader will sometimes, but not always, notice a change in style, habitual vocabulary, or sources. And we are not the first to wonder -- in the case of many masechtot this is an old issue on which later commentaries have already done the work and recent printed editions may even mark the transition on the page.
the last perek of pesachim has rashba"m as well as rashi. the perus on tamid is not rashi, nor is the perush on kinnim. the middle of menachos has two printed versions of rashi, it is possible that on is misattributed to him. printed in place of rashi on nazir is the riva"n, rashi's son-in-law. the end of makkos is that riva"n and rabbeinu gershom. the "rashi" on the last perek of sanhedrin (perek chelek) may be misattributed. the perush on nedarim is of unknown authorship. the rashi on avos is actually written by r' simcha, author of the machzor vitri. in menachos 13a there is a long explanation by the rashba"m. most of bava basra is expalined by teh rashba"m. rashi on me'ila is not rashi. (he quotes rashi sometimes)
According to Oz V’hadar, Rashi on Chelek is not actually Rashi; they note, however, that this isn’t so well-accepted. On Daf 90a, footnote נ, they write:
נראה למי שמכיר בלשון הרש״י הקצר והנקי שפירש פרק חלק אינו מרש״י אלא מאחד מתלמידיו, אבל מה אעשה שהרמ״ה העתיק ממנו דיבורים שלימים וכתב על זה ״ורבינו שלמה פירש.״
It appears to one who recognizes the words of Rashi as short and clear that the commentary on Perek Chelek is not from Rashi, but rather from one of his students. But what can I do? The Rama”h already quoted from him complete phrases, writing on this, “Rabbeinu Shlomo explained.”