On what basis do you think that someone's political views should be beyond mere discussion? I'm trying to figure out why--discussing the views held by your fel

On what basis do you think that someone's political views should be beyond mere discussion? I'm trying to figure out why--discussing the views held by your fellow citizen--that is a bad thing. I'm trying to understand how that advances any sort of democratic principle, to draw the line at "you can't talk about what I donate to".