Principles are ways of successfully dealing with reality to get what you want out of life.
Ray Dalio, one of the world’s most successful investors and entrepreneurs, cites principles as his key to success.
A person making suggestions may not have concluded that a mistake will be made--they could just be making doubly sure that the person they're talking to has taken all the risks into consideration. Asking questions to make sure that someone hasn't overlooked something isn't the same thing as saying that he or she has overlooked it ("watch out for the ice" vs. "you're being careless and not looking out for the ice"). Yet I often see people react to constructive questions as if they were accusations. That is a mistake.