We've all heard of Murphy's Law. It has been stated in various forms, generally something like "If something mn go wrong, it will go wrong, and at the worst possible time." We often quote Murphy's Law often in a light-hearted or joking context. But, do we really believe it? What effect does our belief in Murphy's Law have on how we actually operate and design chemical plants? Is our application of Murphy's Law appropriate? How should we be using Murphy's Law?.