In Parashat Kedoshim, amidst the extensive list of commandments governing interpersonal behaviour, the Torah prohibits placing an obstacle before a blind man (lifnei iver). Though the literal meaning refers to someone who actually causes a blind man to trip, Chazal interpret the verse as referring to two additional scenarios: issuing inappropriate advice and assisting someone in the performance of a sin. This shiur will address the latter interpretation of lifnei iver: the prohibition of facilitating the performance of a sin.
The Torah uses an interesting verb to define the prohibition: "Lo titen," literally, "you should not place." This term suggests that the prohibition consists of actually providing the obstacle, in our case the item or circumstances necessary to violate the prohibition. Obviously no prohibition is violated until the victim actually transgresses. However, the essence of the prohibition is the act of the first person in facilitating the prohibition of the second. This opinion is adopted by the Semak in siman 172. The Rambam, however, both in his description of the mitzva in Sefer ha-Mitzvot (lo ta'aseh 269) and in Hilkhot Rotzei'ach u-Shemirat ha-Nafesh 12:14 defines the prohibtion as one who is "machshil" (literally, "causes to falter") his friend into committing a sin. The Chinukh employs a similar language. Both give the impression that the prohibition consists of the actual causing of the violation and not the original action which ultimately caused the transgression. Said otherwise, is the prohibition defined as placing ("titen"), or as ultimately causing the sin?
An interesting consequence of this question might pertain to lifnei iver's definition as a sin in which no action is involved. Sins which do not contain any physical action do not carry corporeal punishments. In the end of his description of the prohibition, the Chinukh designates lifnei iver as a sin without action, without any malkut penalty. This seems consistent with the Chinukh's (and the Rambam's) view that the prohibition consists of causing the sin. Since at the time the sin was committed, no action was performed by the machshil (the first person who facilitates), no malkut apply. If, however, we would adopt the Semak's definition that the prohibition consists of simply committing the act which invites the sin, we might disagree with the Chinukh and define lifnei iver as involving a physical action.
Another interesting question stemming from our original inquiry would pertain to the issue of continuity. Would lifnei iver apply if the machshil acted, and only subsequently - at some later, unrelated moment - the sin was committed? If the sin consists of the action of facilitating, we might not require a direct and immediate sin. If, however, lifnei iver refers to causing a sin, we might only consider cases in which a direct cause can be established. This issue arises in the context of two very interesting gemarot. In Bava Metzia (75b) the gemara applies lifnei iver to someone who lends money without witnesses since he encourages the borrower to deny the loan. Being that the false denial occurs well after the original loan (and is the product of an independent decision on the part of the borrower), we might easily not consider this lifnei iver. In fact, the Pilpula Charifta claims that Reish Lakish does not apply lifnei iver because the sin cannot be considered directly caused by the private loan. Even Rashi, in his explanation of the gemara, writes, "Since [at the time of the loan] the borrower conspires the ultimate denial." Why was Rashi forced to establish the seeds of the denial at the moment of the loan? Perhaps he agrees that lifnei iver may only be applied if a direct linkage of causality occurs between the act of the machshil and the crime of the victim.
A second gemara which alludes to this question appears in Kiddushin (32a), regarding a father who tears his son's garment, thereby forcing him to anger and possibly retribution. As the revenge of the son is also (presumably) delayed and the product of an independent decision on his part, why should this constitute lifnei iver? Interestingly enough, the gemara attributes the lifnei iver to the anger caused, which in turn might lead to some retributory act. Here as well, we sense the insistence of the gemara to locate some IMMEDIATE effect of the machshil in causing the ultimate transgression.
This question might also manifest itself in an interesting machloket Rishonim. If a kohen appoints a yisrael as a shaliach (messenger) to betrothe a divorcee, does the yisrael violate lifnei iver? Tosafot in Bava Metzia (10b) claim that the shaliach does violate lifnei iver while the Ritva in Kiddushin (32b) disagrees. The Ritva bases his argument on the gemara in Sota 44a, which claims that a kohen only violates the prohibition to marry a divorcee when he experiences intimacy with his wife. Since the yisrael had no hand in that act, his original betrothal on behalf of the kohen does not constitute lifnei iver. Here as well, the Ritva demands a direct linkage between the act of the machshil and the violation of the victim. Tosafot evidently was satisfied in any act which ultimately contributes to the transgression.