Discourages Yivum and encuraged Chalitzah. Does the wording of the Torah not seem to encourage Yibum? How could Beis Din talk someone out of this mitzvah?
Ben Berlin, New York, NY
As you wrote, the wording of the Torah encourages Yibum. And this what they used to do.
Aba Shaul however, due to the fear that people would perform Yibum based on personal motivations (beauty, wealth, etc), expressed strong reservations. He claimed that the Torah permits Yibum (in spite of the fact that the Yevamah is his brother's wife), only if one performs the Mitzvah purely for the Mitzvah of Yibum. Otherwise, one comes close to transgressing the serious sin of Eishes Achiv (marrying one's brother's wife) and what's more, the children are close to being Mamzerim. Consequently, the sages, who rule like Aba Shaul, gave preference to Chalitzah.
It is important to be aware of the fact that the Torah sages have the jurisdiction to completely rescind any Mitzvah should the need arise (a concession which is more radical than the one under discussion).
Classical examples of this are the Mitzvos of Shofar and Lulav, which they rescinded on Shabbos, for fear that people will come to carry them in the street (in a town which has no Eiruv) even as they proceed to perform the Mitzvah.
There will be more talk about this later in Yevamos.
Be'Virchas Kol Tuv