Irrefutable

[…]clear and irrefutable evidence of the Cause I have undertaken

True, there had been nothing, in his lifetime, viler than this man. She knew it, there was no other fact within her consciousness that she felt to be so certain; and yet, because her persecutor found himself safe and irrefutable in death, he frowned upon his victim, and threw back the blame on her!

He had formed his mind by Helvetius, whose system he deemed irrefutable, and in whom alone he had faith.

I have listened also to the remarks of counsel, with high interest—and especially will I commend the masterly and irrefutable logic of the distinguished gentleman who represents the plaintiff. But gentlemen, let us beware how we allow mere human testimony, human ingenuity in argument and human ideas of equity, to influence us at a moment so solemn as this.