First principles thinking is a method of reasoning. It requires reducing a thing to its fundamental parts or truths and reasoning up from that foundation.
It enables us to find where our beliefs do not align with reality.
It is a doorway to new ways of doing things.
It is the most effective approach to learning I know.
First principles reasoning stands in contrast to reasoning by analogy — the attempt to understand things by their likeness to something else. Reasoning by analogy isn’t inherently bad — analogies can be very helpful for quickly grasping an idea. But analogies, especially bad ones, can obscure the true nature of a thing and lead to false assumptions or confusion.
It’s like assuming that because a tiger has stripes and is dangerous, then other animals with stripes are also dangerous, like the lionfish — which gets its name from the stripe-less lion. That’s not to say the lionfish isn’t dangerous, it is. But unlike both the lion and the tiger, the lionfish’s danger comes from its venomous spikes.