Arbitrary - lacking any natural basis or substantial justification; determined by whim with little thought.
This term was originally from the Latin arbitrari, derived from arbitr- or arbiter, meaning “to witness.”
Mark Twain’s Huckleberry Finn contains many instances of Huck’s arbitrary choice of actions, such as when he chose not to accept the Widow Douglas’s home as his own, preferring to run away instead or, as Huck stated in the second paragraph of the novel, “ . . . when I couldn’t stand it no longer I lit out.”
Did this raise a question for you?