Reliable computing is essential. There is no feasible alternative.
Modern societies rely more and more on computer systems.
Usually, our systems appear to work successfully, but there are sometimes serious, and often minor, errors. Ever increasing reliance on computer systems brings ever increasing need for reliability. Validated computing is one essential technology to achieve increased software reliability. If the enclosure is narrow, we are certain that we know the answer reliably and accurately. If the enclosing interval is wide, we have a clear warning that our uncertainty is large, and a closer study is demanded.