The Rishonim (such as Tosafot, Shabbat 3a, s.v. bava) note that while the Biblical prohibition to help another to sin, from the verse “Lifnei iver lo titten michshol (‘you shall not place a stumbling block before the blind, Vayikra 19:14)”, only applies when the aid is integral to the sin taking place, there is nonetheless a rabbinical prohibition (m’sayea l’idei ovrei aveirah) to help a transgression happen to any degree, even when it would happen in any event. As later authorities note (see Resp. Sha’arei Ezra, 103), this prohibition may be a rabbinic version of “Lifnei Iver”, but it may also come from a different source, the responsibility of Jews toward each other (arvut), and the obligation to rebuke one who is sinning. One ramification of this distinction may be that while the Talmud is explicit that “Lifnei Iver” applies when dealing with any person, “arvut”is a concept linking Jews specifically (see Resp. Chatam Sofer, Y.D. 19). The Klausenberger Rebbe (Resp. Divrei Yatziv, Y.D. 47) writes that the rabbinical prohibition only applies when it is definite that a transgression will take place. (See also Resp. Meshiv Davar, II, 32, for a discussion of situations where the prohibition is suspended in the interests of maintaining peace; see also Resp. Dor R’vi’i, I, 13:2; Resp. Minchat Elazar, I, 53; Resp. Chavalim B’N’imim, Chid. Sugyot, 31:2).