first-principles

What

First-principles reasoning means refusing inherited assumptions and deriving conclusions from base truths. Step 1: state what you believe to be true about the problem. Step 2: for each belief, ask "is this a fact, or did I inherit it from convention?" Step 3: discard the inherited beliefs and rebuild from what remains.

Elon Musk's classic example: "batteries are expensive" → why? → materials → materials are cheap → rethink assembly. In software: "we need a database" → why? → persistent state → what's the simplest persistent state? The key test: "would this design make sense to someone who had never seen this domain before?"

When to Use

Apply first-principles thinking to high-stakes decisions where inherited assumptions may be hiding better solutions. It is expensive — do not use it for every micro-choice. Use it when analogy reasoning ("we do it this way because that's how X does it") would lead to a suboptimal outcome.

How

1. State every belief you hold about the problem.
2. Challenge each belief — is it a fact or inherited convention?
3. Discard inherited beliefs. Rebuild from undeniable base truths.
4. Verify: would this design make sense to a domain newcomer?
5. Beware the anti-pattern of defaulting to analogy reasoning instead.