There are two types of payment in the Torah when it comes to claims. The first is mamon, which is compensation. If a person causes another person damages, or borrows money from somebody, he needs to reimburse him. And if he causes them a loss, for example, he needs to pay damages for what he caused. That's what the payment of mamon is. There's a loss, there's something owed, and he's compensating him for that.
Number two is a knas, which is a fine or a penalty. It's a payment made for doing something wrong to somebody, but it's not correlated to the loss that person incurred. It's a penalty for something wrong that was done. The difference between the two, in terms of the shevuat ha-pikadon (oath concerning a deposit) that we're talking about, is that a shevuat ha-pikadon would only make a person pay mamon, but it would not make him pay a knas. What do we mean by that? When it comes to a knas that a person may owe, even if he admits it, that doesn't force payment of the knas. Only when somebody admits mamon—when he admits that he owes money—does that admission do anything to him.
So therefore, if you could apply the shevuat ha-pikadon, a person would only have to bring a korban (offering) if he lied and took that shevuah—that swear—falsely, and only if that lie got him out of having to pay. That would only apply to mamon: if he lied about the fact that he didn't owe somebody money, and the shevuah he took freed him from payment. So when it's eventually found that he lied, he then has to bring a korban. But when it comes to a knas, let's say a person swore that he didn't owe any money in terms of a penalty. Even if he admitted it and didn't lie, he wouldn't have had to pay. That doesn't cause payment. So therefore, the shevuat ha-pikadon he makes in this situation, with a knas, doesn't do anything for him; it didn't really save him in any way, because admitting it wouldn't have done anything for him. So therefore, there's no obligation to bring a korban. We'll spell it out more in the next two mishnayot.
The Mishnah says: If somebody says to a man, “You violated my daughter, you raped my daughter, or you seduced my young daughter,” and he denies it, saying, “No, I didn't violate her, and I did not seduce her,” then the person making the claim—the father in this case—tells him, “I am putting a swear on you that what you just said is true. Swear to me that you're telling me that you didn't rape her or seduce her.” If he later admits that he swore falsely, he's obligated to bring a korban, because he denies a claim that is for compensation. When it comes to rape or seduction of a young girl, there's boshet, there's embarrassment, and all different types of compensation that the man who violated her would have to pay. There's also an additional knas, an additional penalty. Of course, the Tanna Kamma (first tanna) would say that the violator would not have to pay if they later found out that he was lying, because he can't bring a knas upon himself through his own admission. But when it comes to the boshet component, the embarrassment component, the Tanna Kamma says that since it's within the world of mamon, of compensation, the lie—his denying everything—and the shevuah he took, once it's eventually found that he was lying, bring on the obligation of a korban.
But Reb Shimon disagrees. Reb Shimon poter. Reb Shimon says, “No, he's exempt from bringing a korban.” A person does not bring a penalty payment; he doesn't have to pay a knas by his own admission. And therefore, what Reb Shimon is really saying is that when this man, the father, accuses the person of violating or seducing the daughter and wants payment, he is really talking about the knas payment. His claim is really about the 50 shekalim (shekel) that he gets as a penalty from the violator or the seducer. Therefore, he's not really going after the boshet. He's not going after the embarrassment, which is in the class of mamon. He's going after the knas. So when this person denied it, it wasn't within the world of shevuat ha-pikadon, for which he would be obligated to bring a korban. And therefore, says Reb Shimon, he's poter. Again, his denial didn't really save him from anything, because if he admitted it anyway, he wouldn't have had to pay. So therefore, the shevuat ha-pikadon didn't save him, and Reb Shimon says he is poter.
The Chachamim (Sages) responded, saying, “No. Even if we don't pay a knas on our own, we pay boshet on our own as well.” They replied to Reb Shimon, “How could this be? How could you tell me that the man here doesn't have to pay anything, even though he may not have to pay the knas, the 50-shekel penalty for admitting it? You're right. That's for sure out. What about boshet and pegam? What about the penalty for shame and the reduced value of this woman now that by his own admission, he would have to pay?” In the view of the ha-Chachamim, the father's main claim is on these: the boshet and the pegam, the shame and the reduced value of the daughter. Now it's going to be tougher for her to get married, and her dowry would be worth less. So what the father is really claiming is that he could collect these, because even for these, the shevuat ha-pikadon, when it comes to a lie he told about them, would have saved him from paying them. So now that we've found out that he was lying, he should have to bring a korban for the lie about the boshet and the pegam.