Perspective—I feel that's such a pivotal concept, maybe it could even be called a "practice," for a well rounded mind. The ability to view information from vantage points angles than one's own.
I've been working a lot with the idea of existing contradictions and I believe they can be applied to the individuals thought alone, as well. One person can contradict themselves in feeling and in logic when analyzing a scenario—both individual viewpoints are equally valid, they exist simultaneously, and they each contradict the other.