Kirk didn't have to defend his theory.

His aim was to defend his theory in new contexts and modify it, as necessary.

They defended their theory at a cryptography workshop held in Belgium in September 2012.

They defended their theory that a tire popped by a scrap of runway debris had ruptured wing fuel tanks, starting a fire.

Relative to the scientific knowledge of the time, these arguments were sound ones and Copernicus could not satisfactorily defend his theory against them.

More puzzling is why the family continues to defend Mr. Pepper's particular theory.

He'd had a right to his stubbornness, a right to defend his theory, flawed or not.

How do you think Freud would account for them, if he wanted to defend his theory?

Jára Cirmman was invited to defend his theory to the philosophical congress in Basel.

Darwin was too able a thinker to try defending his theory with such a self-defeating catch phrase.