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.
Some people make decisions based on logical analysis of objective facts, considering all the known, provable factors important to a given situation and using logic to determine the best course of action. This approach is an indicator of a preference for thinking and is how you'd hope your doctor thinks when he makes a diagnosis. Other people--who prefer feeling--focus on harmony between people. They are better suited to roles that require lots of empathy, interpersonal contact, and relationship building, for example HR and customer service. Before we had assessments to identify these differences, conversations between "Ts" and "Fs" were really frustrating. Now we laugh as we bump up against our differences, because we know what they are and can see them playing out in classic ways.