I mean, isn't that one of the points of class? That someone who knows more than you can guide you along the path to greater knowledge?
No such thing here.
At Shimer it's been my experience that not only do facilitators get disagreed with and argue down, but we also carry on class when they're not here. Sick, or out of town? Class marches on. Twice now in my Social Sciences 3 class our facilitator has been absent, and both times it's carried on anyway. The first time this happened, we discussed Marx in a lively debate that left me happy with our understanding and using dialogue, because not only had everyone showed up regardless of the presence of a facilitator, but we had also had a great discussion that clarified a lot of the text and brought up many interesting interpretations.
Sometimes we'll get substitutes if other faculty are free, but for the most part we do fine, especially if the group dynamics are good, like in my Soc 3 class. I might not have agreed with everything Marx said, but I got a good deal out of the discussion, and the nonpresence of the facilitator only strengthened our confidence in our discussion abilities.