Musk says: when I look at things, I look at the root and don't compare myself with others—once you compare yourself with others, you become just like them, and no matter how impressive, it's nothing special. But if, like me, you look at the root, you might just be able to grow a whole new big tree from it. Its originator, Aristotle, put it this way: everything has a foundation, and this foundation absolutely cannot be changed—without it, the thing simply isn't a thing anymore.
So first principles are the root and foundation. First-principles thinking means starting from the fundamentals to find more reasonable new methods.
The reason Musk always comes up with disruptive breakthroughs is precisely that he can always identify cooperation models, cognitive structures, and technological path dependencies that people have long considered perfectly reasonable, but which are actually incorrect or imperfect.
When it comes to reducing the cost of rockets and satellites, he kept asking: why must this thing have this part or that function? As long as it can get into orbit, can't we just remove everything else that isn't needed? Regarding Tesla's brake problem, while experts were researching how to improve braking technology, his thinking was: why not just remove the brakes? Although this is a joke using first-principles thinking to mock Musk, looking at it the other way, that's exactly where the explosive power of this kind of thinking lies.
The first-principles way of thinking means, on the basis of clarifying the essence, using critical thinking to break down the unreasonable connections within phenomena. Frequently ask yourself 3 simple questions: Why is it this way? Does it have to be this way? Couldn't it be another way? Make these 3 questions a habit, and you too will surely overturn some unreasonable things around you and find your own path to innovation.