Taking her cue from Will Rogers, who said, ``It's not what you don't know that can hurt you; it's what you know that ain't so,'' Eileen Shapiro exposes corporate enemy number one: self-deception. Citing dozens of case studies, ranging from the funny to the tragic, she focuses on the eight most common corporate hobbyhorses--corporate ``truths,'' often based on past successes--that persistently lead smart managers into making bad decisions. And, she offers clear guidelines that will sharpen managers' perceptions and help them avoid current and future self-delusions that can kill their companies' and their own chances of success.