“First Principle” is a foundational proposition or assumption which cannot be deduced from any other proposition or assumption.
Great philosopher Aristotle was the first to use the concept of “First Principle” which he described as the process of acquiring knowledge of “primary causes”, down to it’s elements.
Elon Musk’s recipe to work with “First Principle” involves three step:
a) Write down the problem and the assumptions (usually carried forward as a baggage of someone else’s presumption or some analogy) which you have.
b) Apply the “First Principle” to those assumptions, and see if they (assumptions) still stand strong.
c) Once you are clear whether the assumptions hold true of “First Principle” (more often than not, they would not), work towards finding the new solution with the “FP” in mind.