This way you can inquire after their exact position, why they hold that position, and without taking a side gather whether they're open to accepting another position whilst presenting viable alternatives in a reasoned and unobtrusive fashion.

What you actually appear to be doing in this exchange is framing the debate (this is not a neutral action) under the guise of being a neutral observer. If your arguer is experienced enough to see what you're doing, he will challenge you on it probably in a way that will result in a flame war. If he isn't experienced enough he may see what appears to be a logical argument that somehow doesn't seem persuasive and this may put him off the whole concept of logical arguing.