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.
I don't use the word "leadership" to describe what I do or what I think is good because I don't believe that what most people think of as "good leadership" is effective. Most people think a good leader is a strong person who engenders confidence in others and motivates them to follow him/her, with the emphasis on "follow." The stereotypical leader often sees questioning and disagreement as threatening and prefers people do what they're told. As an extension of this paradigm, the leader bears the main burden of decision making. But because such leaders are never as all-knowing as they try to appear, disenchantment and even anger tends to set in. That's why people who once loved their charismatic leaders often want to get rid of them.
This traditional relationship between "leaders" and "followers" is the opposite of what I believe is needed to be most effective, and being maximally effective is the most important thing a "leader" must do. It is more practical to be honest about one's uncertainties, mistakes, and weaknesses than to pretend they don't exist. It is also more important to have good challengers than good followers. Thoughtful discussion and disagreement is practical because it stress-tests leaders and brings what they are missing to their attention.
One thing that leaders should not do, in my opinion, is be manipulative. Sometimes leaders will use emotions to motivate people to do things that they would not do after reflecting clearly. When dealing with intelligent people in an idea meritocracy, it is essential that one always appeal to their reason rather than their base emotions.
The most effective leaders work to 1) open-mindedly seek out the best answers and 2) bring others along as part of that discovery process. That is how learning and getting in sync occurs. A truly great leader is appropriately uncertain but well equipped to deal with that uncertainty through open-minded exploration. All else being equal, I think the kind of leader who looks and acts like a skilled ninja will beat the kind of leader who looks and acts like a muscular action hero every time.