Reasoning by analogy is the default way most people think. It works like this: something similar was done before in a particular way, so we do it the same way. This is efficient — you do not have to think from scratch every time. But it has a critical flaw: you inherit all the assumptions, constraints, and limitations of the previous approach, even the ones that no longer apply to your situation. First principles thinking is the alternative. It means stripping a problem down to its most fundamental, verifiable truths, and then reasoning upward from there. Not 'how did others solve this?' but 'what do I actually know to be true about this problem?' The gap between what you inherited and what you actually know is where the most powerful solutions live.