first-principles

Reasons a problem up from fundamental, established truths rather than by analogy to how it is already done. A first principle, in Aristotle, is a foundational proposition that cannot be deduced from any other. The discipline is to strip a problem down to the few things that genuinely hold (physical limits, definitions, hard constraints, the real goal) and rebuild from there, ignoring inherited form. Catches the failure where "that is how it is done" is mistaken for "that is how it must be done."

The method, the bedrock test (fact versus assumption), and the reconstruction step live in references/first-principles.md. Load that file before reasoning and follow the separate-fact-from-assumption rule exactly.

When to use

The user is stuck inside a conventional approach and wants to know whether the convention is load-bearing or merely inherited. The unit of analysis is one problem and the received way of solving it. It pairs with neighbors but is distinct from them:

• If the job is to break one problem into clean, non-overlapping branches, use mece-decomposition.
• If the job is to list the assumptions a plan rests on and rank them by fragility, use key-assumptions-check.
• If the job is to find the worst outcome and reason backward to avoid it, use inversion.
• If the job is to trace a failure that already happened to its origin, use root-cause-analysis.

First-principles reasoning is expensive. Reach for it when convention is costly, suspect, or untested, not for routine problems where reasoning by analogy works fine.

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