My feeling is that abstractions are good in seminars for graduate students. To really have a discussion even around principles, I think you need to present concrete proposals and then invite interventions in which people are asked to express an opinion on either side, drawing upon principles. But asking for the principles as such is an abstraction, and I would say that most people don't think that way. If they do, it's because it's imposed on them by the situation. It's not the way they naturally operate.
Yes, I think the principles are important, but I do think that what I mentioned is the best way to get at them: to say here's the system, and here are the alternative systems that, based on our discussions, best reflect our views and those of the people who've presented their positions to us. Now we take it to the people in our districts and we ask them. When they choose, when they express a preference for one or the other system, we ask them to explain their preference in terms of these values—not the other way around.