First Principles

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Overview

Most reasoning is reasoning by analogy: X resembles Y, so do what Y does. It is fast, usually right, and silently inherits every assumption baked into Y — including the wrong and expensive ones. First-principles reasoning strips a problem to statements that cannot be reduced any further — physical law, mathematical identity, a definition, or a cited empirical fact — and rebuilds the answer using only those.

This is one of three composable motions in the deciqAI collection: first-principles decomposes downward to bedrock; occams-razor chooses sideways among competing accounts you could build on top of bedrock; second-order-thinking traces forward through time and consequence. Compose: reduce to find the foundations (here), pick the simplest hypothesis that fits the evidence (occams), then trace where that pick actually leads (second-order).

When to Use

Use when: decision is justified mainly by "that's how it's done" or authority; conventional answer is expensive/hard to reverse (pricing, architecture, business model); structuring a knowledge artifact from irreducible elements; pressure-testing an AI hype claim or AI-adoption cost assumption ("is AI too expensive / too cheap to deploy") against the underlying physics rather than the API sticker price; user says "from first principles," "from scratch," "why do we believe this," "tear this apart."

Skip when: routine reversible decision where convention is cheap (which linter) — tearing down is theater; facts aren't gathered yet; user asked for speed and the conventional answer.

Coaching Novices (Adaptive Front Door)

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