I try to maintain a good equilibrium between the comfort and consolation of the confirmation of my beliefs and the stimulation offered in debate and disagreement. When people agree with me or tell me I am right, especially people I respect, it creates a warm feeling. On the other hand, when someone disagrees, it helps me to clarify my own thoughts.
What is the origin of the disagreement?
(1) I have not expressed myself clearly.
(2) I have been clear, but my interlocutor has substituted a less nuanced version of my argument and is disagreeing with that.
(3) The interlocutor has understood my argument completely, but will not accept it because s/he simply believes a countervailing claim is stronger. Or it might be a case where the disagreement comes down to irreducible appeals to individual differences in temperament, taste...
(4) I was clearly wrong and someone is setting me straight.
(5) My interlocutor simply has such a strong stake in a particular position, that s/he is not willing to listen.
(6) The disagreer is a defender of the indefensible: plagiarism, racism, piracy on the high seas...
(7) The disagreer is arguing in bad faith, acting as a concern troll or "Kent Johnson."
This is not an exhaustive list, but it will do for now. In cases 1-4, disagreement is productive (the way a cough can be "productive") in producing the clarification of claims and opinions. In the last three situations, disagreement is an unproductive irritant rather than a stimulation.