Students are uncomfortable defending views they disagree with. Depending on how you elect to assign positions, students may find themselves defending a position they disagree with (or critiquing a position they agree with). They might it challenging or even problematic to argue contrary to their personal beliefs, even in an artificial debate setting.
Explain the purpose of section debate. The aim of hosting a debate, at least in the context of a discussion section, is to help develop a better understanding of a relevant issue or argument (as opposed to, say, advance a specific position or even just show off rhetorical prowess). A discussion section affords a safe context to fully explore and understand positions, even if we think they are wrong. Even if we think a position is wrong, we should hope to reject it for the right reasons. Clearly articulating a defending that position in a section-debate context offers us the opportunity to make sure we are at least doing that.
Offer the option to trade sides or defend a third option. If a student is seriously uncomfortable with defending their assigned view, they can either switch positions with another student, or attempt to argue for some third option. If you do offer students the opportunity to argue for a third option, make sure to work with the student before-hand to ensure that this option is at least a coherent position.
Students become too focused on “winning” the debate. The seemingly competitive structure of a debate can encourage students to focus on rhetorically “beating” the “other side,” rather than using objections as an opportunity to develop their own views and provide their debate counterparts the same opportunity to develop their views.
Explain the purpose of section debate. Before section, make clear that the aim of hosting a debate, at least in the context of a discussion section, is to help develop a better understanding of a relevant issue or argument. It is not aimed at advancing a specific position or establishing rhetorical superiority.
Provide a end-of-debate debrief. At the end of section, run through major points of discussion and remaining questions. This will allow you to conclude the section with an emphasis on specific learning arrived at through the debate, rather than on the debate exercise itself