Keep Your Identity Small (2009) is an essay by Paul Graham which describes something I've intuitively practiced since my early twenties. But I'd never formalized the thought.

My set of justified true beliefs come not as an expression or extension of my identity, but from reasoned logic combined with a set of morals, ideal outcomes, and other justified true beliefs. I've internalized the idea that I shouldn't let these beliefs constitute my identity.

A related idea is that of “Strong Opinons, Weakly Held", a framework for thinking espoused by Palo Alto's Institute for the Future. The idea is that opinions should be "weakly held" — be unattached to the idea, so that you do not irrationaly reject its refutation. The other side of this coin is that you must not let this lack of attachment dampen your rigor, passion, or strength in forming, understanding, and justifying your beliefs.