DOCTRINAIRE
doctrinaire
(adjective) stubbornly insistent on theory without regard for practicality or suitability
dogmatist, doctrinaire
(noun) a stubborn person of arbitrary or arrogant opinions
Source: WordNet® 3.1
Etymology
Noun
doctrinaire (plural doctrinaires)
A person who stubbornly holds to a philosophy or opinion regardless of its feasibility.
(historical) In France, in 1815-30, one of a school who desired a constitution like that of Britain.
Adjective
doctrinaire (comparative more doctrinaire, superlative most doctrinaire)
Stubbornly holding on to an idea without concern for practicalities or reality.
Source: Wiktionary
Doc`tri*naire", n. Etym: [F. See Doctrine.]
Definition: One who would apply to political or other practical concerns
the abstract doctrines or the theories of his own philosophical
system; a propounder of a new set of opinions; a dogmatic theorist.
Used also adjectively; as, doctrinaire notions.
Note: In french history, the Doctrinaires were a constitutionalist
party which originated after the restoration of the Bourbons, and
represented the interests of liberalism and progress. After the
Revolution of July, 1830, when they came into power, they assumed a
conservative position in antagonism with the republicans and
radicals. Am. Cyc.
Source: Webster’s Unabridged Dictionary 1913 Edition