small-minded

conservative, hidebound, old-fashioned, reactionary

blindfolded, blinkered, insular, parochial, provincial

biased, one-sided, partial, partisan

inflexible, ironbound, obdurate, obstinate, rigid, set, stubborn, unyielding, wrongheaded

bigoted, intolerant

biased, jaundiced, one-sided, partial, partisan, prejudiced

brass bound, hidebound, old-fashioned, reactionary, stodgy, straitlaced (or straightlaced), stuffy

dogmatic (also dogmatical), opinionated