If you’re arguing with someone you like / respect, and you disagree in degree not kind, emphasize that you are just at different points of the same spectrum. This goes a long way to keeping things positive.
For example, suppose a person says, “I believe you can never think about yourself too much — introspection is very important.”
A response emphasizing disagreement of degree not kind would first establish the extremes: “Well surely thinking about yourself every second of every hour of every day is too much, right?”
“Well, of course.”
“OK. So we both agree in the extreme case. You just think a few hours a day of explicit reflection is worth it, where I think more than 20 minutes a day leads to narcissism.”
Bottom Line: A great way to keep an argument cordial is to emphasize your disagreement of degree not kind (if this is so) and by establishing the extremes of the spectrum in a way you both agree. Find that point of agreement / common ground. Then note that you are simply at different points on the same spectrum.
This is one sure way to say the opposite without being hurtful. But it fits occasions where there are just two people to that debate and not three, in which case the majority will overwhelm the lone dissenter and chances are, he may not offer up his dissent unless he has a compelling reason to or holds a diametrically opposite view with loads of supporting data.