1. Of, relating to, or characteristic of someone who is inflexibly attached to a practice or theory: Donald had doctrinaire notions about politics that just didn't make sense.
2. Determined to use a specific theory or method and refusing to accept that there might be a better approach: One senator is a doctrinaire conservative and the other one is a doctrinaire liberal or "progressive" and neither one has a practical approach to solving the financial situatioin.

A reference to doctrinare beliefs that some people will not change nor accept any suggestions from other others nor even when such opinions don't work and have been proven impractical.