While some Tanaim hold that the nazir’s self-denial is itself sinful, the majority view seems to be that nezirus can bring a person to great spiritual heights. Various pesukim refer to the nazir and the prophet in the same breath, implying a similar status. Why then must the nazir bring a korban chatas? Ramban answers that the chatas is a penalty for the nazir ending his nezirus and not remaining on this plateau of spiritual perfection. Tosfos (Ta’anis 11), however, denies the basis of the question. The nazir surely reaches great spiritual heights, but at the same time is guilty of a minor infraction of foregoing the pleasures of the world. The greater good is worth the peril of the lesser evil. Tosfos notes that even where required by halacha to take on a vow of nezirus – “ha’ro’eh sotah b’kilkula yazir min ha’yayin” – the nazir is nonetheless is guilty of a minor sin.
Rav Bloch in Shiurei Da’as wonders what Tosfos means by this last point. How can a person be called a sinner if he/she is following the path required by halacha?!
“Ain tzadik ba’aretz asher ya’aseh tov v’lo yechetah.” The simple understanding of the pasuk is that even the greatest people experience failures – 99 out of 100 actions of a tzadik may be raiseworthy, but there is always that 1 out of 100 misstep. R’ Chaim Volozhiner, however adds an additional insight: the pasuk is not just speaking of quantitative tzidkus, but qualitative tzidkus as well. Even acts which are perceived as righteous are only 99% pure, but there is an inevitable element of “lo lishma,” selfishness, wrongful motivation, which creeps into all deeds. Even a tzadik cannot act with pure intention of “tov” without cheit tainting his deeds.
As psychologists put it, our actions are overdetermined, i.e. there are multiple individually sufficient causes that drive behavior. The Torah is realistic in its assessment of personality – even good people who do the right thing do so with mixed motives.
Rav Bloch interprets Tosfos as referring to the motivations that bring one to accept a vow of nezirus. Becoming a nazir may, under certain circumstances, be the 100% right thing to do, but that doesn’t mean the potential nazir's motives are 100% pure is making that leap. When we submerge the totality of our personality into an endeavor, even a positive endeavor, the bad traits that are inherent within us come along for the ride. That initial small lacking of proper intention stands out all the more in light of the tremendous spiritual heights reached by the nazir, but ultimately does not diminish in the larger sense from the value of the commitment.