What do you mean by "extremist" ideas? What makes someone who thinks their country's immigration policies should be crafted in such a way as to provide maximum benefit to their country's own citizens an extremist?
I believe what I'm getting at is how to avoid that unproductive ideas dominate the discussion. But not only unproductive, specially harmful ideas that freak everyone out and play into people's fears, robbing them from the opportunity to have a rational discussion.