You can also take the socratic approach and just ask good questions instead of making statements.
Sometimes you don't even have to ask, just mirror your counterpart (repeat his last statement as a question) and make good use of silence. Wu wei all the way.
Yes! I am by nature non-confrontational, but this is how I dissent in a discussion without getting into a heated argument (when the possibility of changing minds goes out the window anyway).
This is still difficult, but better than staying quiet or lying, a path to self-contempt.
Sometimes you don't even have to ask, just mirror your counterpart (repeat his last statement as a question) and make good use of silence. Wu wei all the way.