Can we talk about process first?
It's so tempting to get straight to the issue, especially since you're certain that you're right.
The challenge is that organizations and relationships that thrive are built to go beyond this one discussion. They are built for the long haul, and this particular issue, while important, isn't as vital as our ability to work together on the next hundred issues.
So yes, you're probably right, and yes, it's urgent, but if we can't agree on a process to talk about this, we're not going to get anywhere, not for long.
If the process we've used in the past is broken, let's fix it, because, in fact, getting that process right is actually more urgent than the problem we've got right now. Our meta-conversation pays significant dividends. At the very least, it gets us working together on the same side of a problem before we have to be on opposite sides of the issue of the day.