Our Gemara on Amud Beis discusses the halakhic significance of female facial hair if it is considered like a beard. The matter is relevant regarding whether the laws of leprosy of the beard will apply to this area or the laws of skin leprosy, which have different criteria. The Gemara seems to consider the possibility that even though the verse explicitly includes female facial hair as part of the beard leprosy (Vayikra 13:29, "A man or woman who has a plague upon their beard"), the baraisa still needs to teach that she can be purified as well. To this, the Gemara responds:

כֵּיוָן דְּבַת טוּמְאָה הִיא – בַּת טׇהֳרָה הִי.

Since impurity applies to a woman, surely purity must likewise apply to her.

This implies that it is counterintuitive to impose impurity without the ability to purify. If so, this contradicts a different Gemara (Nazir 61b) that assumes if not for a special additional verse, a Gentile might acquire impurity but not be able to become purified through the Red Heifer. Gemara Nazir seems to hold the exact opposite assumption, that impurity can be imposed even without a way to become purified.

I believe Rashi on our Gemara ("LeTaharas") avoided this question by interpreting the purification of the beard area under discussion as the rituals of purification. Meaning a Metzora shaves beard hair when undergoing purification, so would a female beard need to be shaved? The Gemara never asserted that becoming impure automatically qualifies for being eligible for purification; rather, the Gemara is saying, "If the facial hair is treated as a beard for the laws of impurity, so too it will be for the ritual of purification and need to be shaved."

If I'm right, then Rashi avoids contradicting the Gemara in Nazir. However, the simple reading of our Gemara is that it was the actual eligibility for purification that presumptively must be granted if laws of impurity apply. If so, how do we reconcile with Gemara Nazir? It could be that this presumption was only for a Jewish person and not a Gentile. The Gemara Nazir was discussing a Gentile without an additional derasha considered that a Gentile can become impure but not become eligible for purity through the Red Heifer. This is a credible distinction for two reasons: 1. A Gentile does not have to offer sacrifices, frequent the Temple, nor give Terumah, so his need for purification is less. 2. The Red Heifer is a sacrificial ritual, and perhaps someone outside the covenant cannot qualify for this ritual.

In any case, taken metaphorically, this teaching has a powerful message. Our Gemara considers it untenable for a Jewish person to become impure and remain stuck in that state. If one becomes impure, then he or she must be eligible for purity. Rav Nachman says, "If you believe that you can damage, then believe that you can fix."