Nedarim 21b - Pesach and Charata

One of the yesodos of hataras nedarim is the two way in which the neder can be removed: pesach or charata. The Ran defines the terms: "Pesach" - A situation that if he realized at the time he made the neder, he would never have made the neder to begin with. The method of "pesach" manages to turn the neder into a neder ta'os as if it were made based on a false premise. "Charata" - Although there is nothing that would have stopped him from making the neder originally, he now realizes that the neder was made without proper yishuv ha'da'as i.e. out of anger and he really never meant it. This is called "Charata d'meikara". There is another type of charta which is called "charata d'hashta" that does not work according to anyone - when one regrets the neder from now on but does not regret it from its inception, rather he wants it to be removed from here on in. There is also a situation that is between "pesach" and "charata d'meikara" - when one says that if people would have appeased him originally then he would not have made the neder - this is not quite a "pesach" since he requires the intervention of others, but it is better than "charata" since there is something that would have stopped him from making the neder originally.

Based on the Ran's explanation that "pesach" renders the neder a mistake since its inception, it is not clear why you need a chacham to be matir it. Every person who realizes a situation that if realized originally would have detered him from making the neder, it should be null and void by itself without chacham intervention? The Maharit (1:19 quoting his father) and the R' Shlomo Eiger quoting the Mabit both say that m'doraysa when there is a "pesach" there is no need for a chacham, but the rabbanan didn't want a free for all and therefore insist that a neder only be removed by a chacham removing it. Based on this approach, the gemara on 9b that says that if one regrets the acceptance of nezirus it would turn his korban into chulin b'azara, works very well. Even though he does not go to a chacham to remove the neder, the very fact that a "pesach" exists renders the neder a ta'os and the korbanos will be chulin b'azara. However, the Ran who is madchik in that gemara that the existence of a "pesach" would not render the neder a ta'os without the process of a chacham being matir it, clearly rejects the notion of the Mabit and holds that even m'doraysa a chacham must be matir when there is a "pesach".