Thoughts on how to debate productively
People almost universally underestimate how biased they are. Debates almost never look how debates would look between two rational people. See also here.
There is good evidence that a large part of our reasoning abilities evolved to help us win arguments rather than arrive at truth. This is consistent with our tendency to engage in motivated reasoning.
It is likely that the distinction between near/far thinking is helpful here, and that techniques that bring us closer to near mode reduce bias.
There is evidence that prompting people to explain causal relationships makes them lower their confidence in their positions, as opposed to asking them to give a list of reasons. This is consistent with bias being reduced by near mode thinking.
A speculative technique in the same vein would be to focus on very specific situations and hypothetical examples. Debating whether decentralization or adoption is more important puts people into far/abstract/idealistic mode. Debating how the probability of a specific consequence of centralization would change after a specific proposal was implemented puts participants in near/concrete mode.
One technique for keeping the discussion in near mode is for everyone in the debate to answer the question "what evidence would make you change your mind?"