OBSTINATE, adj. Inaccessible to the truth as it is manifest in the splendor and stress of our advocacy.

Ambrose Bierce (1842–1914?) American writer and journalist

“Obstinate,” The Devil’s Dictionary (1911)
    (Source)

Originally published in the "Cynic's Word Book" column in the New York American (1904-10-05) and the "Cynic's Dictionary" column in the San Francisco Examiner (1904-10-31).

See "Resolute."