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.
Don't make the mistake of just having the case-at-hand discussion, because then you are micromanaging (i.e., you are doing your managee's thinking and your managee will mistakenly think that's okay). When having the machine-level discussion, think clearly how things should have gone and explore why they didn't go that way. If you are in a rush to determine what to do and you have to tell the person who works for you what to do, make sure to explain what you are doing and why.