Is there a discipline within philosophy which deals with how to acquire and hold strong opinions and yet be emotionally detached from those options. This would make it easier to represent an opinion that is being attacked while keeping a calm open mind. Please forgive my philosophical ignorance.
Not really, although people in any discipline are used to the idea that the academic ideas one has are likely to be attacked by others who disagree with them. In philosophy as elsewhere many find it difficult to distinguish between attacks on their ideas and attacks on the producers of the ideas, and sometimes these are the same attacks, of course. Promotion, employment and salary may depend on the reception of one's work and so it is not that easy to be detached from how it is regarded by others. Should we seek to achieve a calm open mind, as you suggest? Perhaps we should encourage more passion in academic life to avoid that sense of placid complacency that often seems to prevail, especially in philosophy.