I recall informally proposing a test to disprove a debate-inspired claim that the A-10's anti-tank cannon would "never" destroy tanks in "all future wars." The test would have cost a few hundred thousand dollars. The colonel hearing this proposal told me something like this: When the Air Force needed a new plane - and its reasons were usually valid-it understood that opposition could arise for various reasons, financial, ideological, or parochial. Therefore, the service had to make a strong case, and part of this involved demonstrating that the current plane was dangerously unsatisfactoy. In this case, the A-10 was the current model, and thus, did I really think the Air Force would give me money to prove it wrong?
From "The Warthog and the Close Air Support Debate" by Douglas Campbell, page xi (found on google books, don't expect me to know the full book)..