certitude

When Russert asked him to confirm that the picture didn't show him, he replied, "I can't say with certitude."

This certitude admits no hesitation, no ambiguity; it is absolute; as soon as it has obtained assent, it remains immutable.

Upon arising, he was another person, and certitude, pure and clear certitude did not abandon him an instant until evening.

He grinned viciously, for the certitude of his bidding had at last shaken the king.

This certitude was very comforting, and he went on talking about the finding of the body, listening to his own voice complacently.

So the hypothesis of the rotation of the earth would have the same degree of certitude as the very existence of external objects.