SACRAMENTO, Calif. -- Gov. Jerry Brown wasted no time Tuesday in signing a contentious California bill to impose one of the strictest school vaccination laws in the country following an outbreak of measles at Disneyland late last year.
rebuttal - the speech act of refuting by offering a contrary contention or argument. refutation, defence, defense - the speech act of answering an attack on your assertions; his refutation of the charges was short and persuasive; in defense he said the other man started it.
Bob's defense that he did not make the statement is not a truth defense; it is rebutting the assertion that the statement was made at all. The defense of truth in defamation claims means that the asserted statement assuming it was made was true. In your example, that issue never really arises because the complained about statement is one of opinion, not of fact.