Regarding gun control, the first principles at issue are these:
1. Is life more important than liberty or vice versa? (ooh this reverses vs. the abortion issue regarding political lines)
2. Do we trust the government to fully monopolize force? Do we trust the police? the army? Should the government be there primarily to protect us?
3. What are the implications of one interpretatin of the 2nd Amendment on federal power or another?
(I won't go over my view here, except to say it is not a partisan view.)
The reason is that very often we can find common ground over first principles, and this helps with discussing others without putting the other side on the defensive or shaming.