We may appeal to every page of history we have hitherto turned over, for proofs irrefragable, that the people, when they have been unchecked, have been as unjust, tyrannical, brutal, barbarous and cruel as any king or senate possessed of uncontrollable power. -- John Adams

Irrefragable

adj. Which cannot be refuted; indisputable, clearly right, incontrovertible.

We may appeal to every page of history we have hitherto turned over, for proofs irrefragable, that the people, when they have been unchecked, have been as unjust, tyrannical, brutal, barbarous and cruel as any king or senate possessed of uncontrollable power.
— John Adams, Letter to Thomas Jefferson (11-13-1815)

Etymology
Neoclassical Latin, refragari means “to oppose or contest”, the Latin frag means to break, as in fragment and fraction. Same Indo-European root as “break”.