The Law of the Rapist

As in P220, the marriage takes place only if she consents, and he must pay a fine.

Deut. 22:29.

15a.

The Rambam now proves that this verse contains two separate mitzvos, a positive commandment (that he marry her), and a prohibition (that once he marries her, he is never allowed to divorce her).

The Gemara is discussing the types of prohibitions for which the punishment is lashes. When a positive commandment can "remedy" the prohibited act (lav she'nitak l'aseh), one does not receive lashes as long as that remedial act is performed. For example, there is a prohibition against leaving sacrificial meat beyond the prescribed time. Should one leave the meat too long, there is a positive commandment to burn the meat. As long as the meat can still be burned, one is not lashed for the prohibition.

The Gemara then postulates a distinction: perhaps this principle applies only in such a case, where the prohibition (e.g., leaving the meat) always comes before the positive act (burning it). Perhaps when the positive act can come first (called "a prohibition which is preceded by a positive commandment"), one does receive lashes.

This the Gemara disproves with our mitzvah, regarding which we know clearly that one does not receive lashes since he can always remarry her. It therefore asks: "[According to your reasoning,] why [should he not receive lashes]?" — being that the positive commandment comes first.

The point of quoting this passage is to bring the phrase, "a positive commandment," which shows that marrying her counts as a mitzvah.