Question (R. Yudan): According to the opinion that both he and the brothers are not Chayav [Kares] for the Chalutzah, but they are liable for the Tzarah:

It is fine that he is not Chayav for the Chalutzah, for it was already proper to exempt her (he could have done Yibum with her). He is liable for the Tzarah, for it was not proper to exempt her (it is as if she did not fall to Yibum. It is as if she is Eshes Achiv who had children, an Isur Kares).

However, the brothers - what is the difference between the Chalutzah and the Tzarah? (Neither was proper for him!)

Answer (R. Yudan): [A brother is liable for a Tzarah due to the Mes; she was his full wife. However, for the Chalutzah,] you do not know for what he is liable - because [she is like the wife] of the Choletz, or because of the Mes?! (Since the Chiyuv is not clear, it is weak.)

Rebuttal (R. Yosi): Do you think that Chalitzah is a Kinyan? It is only an exemption. The brothers are not liable for her like the [divorced] wife of the Choletz. Rather, they are liable for her because she was the wife of the Mes. (There is no reason to distinguish the Chalutzah from the Tzaros; the question remains.)