Steve Goguen and I regularly discuss all sorts of things, and today he made a fantastic observation and gave me some incredibly sage advice:
I want to give you some advice which I think you’ll find when arguing with someone, especially if you want the argument to be productive. You need to tell the person what parts or assumptions you agree with otherwise you will create an atmosphere where the person will think you disagree on every possible point and they won’t want to continue the conversation. I know you, and I know we are in agreement with a lot of things, but if I didn’t know you there’s no way I would come to that conclusion.
He’s right; when I argue, I am incredibly adversarial and I know it hurts my ability to move the discussion forward. I don’t know why I argue this way, but it’s what comes naturally. I do need to start working on a strategy of discourse that frames the conversation in a win-win atmosphere.
I’m incredibly fortunate to have good friends, like Steve.
Programmer, husband, father, singer, guitarist, tinkerer, reverse engineer, strange, and living in New Jersey. 
Yes, I agree with him.
I need to start using the phrase “I agree with a lot of what you said, but …” more often.
Seeing how we both know you enjoy being adversarial, I think it would be boring if I gave you a bunch of “gee-whiz let’s all get along” and “win-win” advice.
Letting Them Know You Know
I think the key idea is to focus on making sure the other person knows you understand them. This is especially true if you’re trying to sell an idea that’s counter-intuitive. They’ll just think you don’t get it and your counter-intuitive ideas will only confirm their suspicions, especially if your counter-intuitive ideas are based on subtle and nuanced premises.
Mapping Enemy Territory
Making a person understand that you understand them requires patience. You have to take the time to carefully listen to the person you’re arguing with and take the time to ask them honest questions. You’ll need to take your time with this so you can pick up on the nuances of their positions. You don’t have to agree with them, just explain their own ideas back to them in a way that satisfies them. Once you’ve done that, you’ve convinced them you’re worth talking to, and you might even get their ear.
On to the Kill
Now that you’ve convinced them you understand their ideas, you can address your objections by framing it with their ideas and premises.
Found out I should I take my own advice today. Was fighting with my wife and we’d come back to a point which I thought we’d resolved. Turns out I forgot to tell her that I agreed with her on that point. Could have probably saved myself a lot of grief if I had done it in the first place.