IMPARTIAL, adj. Unable to perceive any promise of personal advantage from espousing either side of a controversy or adopting either of two conflicting opinions.

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

“Impartial,” The Cynic’s Word Book (1906)
    (Source)

Included in The Devil's Dictionary (1911). Originally published in the "Devil's Dictionary" column in the San Francisco Wasp (1885-09-12).