When a constraint is treated as fixed ("too expensive", "impossible", "always done this way"), ask whether it's physics or just convention, then rebuild from what's actually true.
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When a constraint is treated as fixed ("too expensive", "impossible", "always done this way"), ask whether it's physics or just convention, then rebuild from what's actually true.
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thinking-first-principles.SKILL.md
---name: thinking-first-principles
description: When a constraint is treated as fixed ("too expensive", "impossible", "always done this way"), ask whether it's physics or just convention, then rebuild from what's actually true.
---# First Principles Reasoning
## Overview
First principles thinking strips away assumptions and conventions to reveal fundamental truths, then reconstructs solutions from those basics. This approach, championed by Elon Musk and rooted in Aristotle's philosophy, enables breakthrough solutions by escaping the trap of reasoning by analogy.
**Core Principle:** Don't accept "that's how it's always done." Reduce to fundamentals, then rebuild.
## When to Use
- Conventional approaches have failed or seem inadequate
- You're told something is "impossible" or "too expensive"
- Designing new systems/products from scratch
- Challenging industry assumptions or pricing
- Problem seems intractable using existing mental models
- You need innovation rather than incremental improvement
Decision flow:
```
Problem intractable? → yes → Are you reasoning from analogy? → yes → APPLY FIRST PRINCIPLES
↘ no → Already at fundamentals
↘ no → Standard problem-solving may suffice
```
## When NOT to Use
- The constraint is genuinely physics/cost/regulation, not convention — verify, then accept it and move on.
- A well-trodden, working solution already exists; reinventing from scratch adds risk without lift. Use the convention.
- Routine implementation where the "why" is settled — don't re-derive a standard library, protocol, or known-good pattern.
- Time-critical incidents: act on the most likely cause first (occams-razor), reserve first-principles for the post-incident redesign.
## Trigger Card
When a constraint is treated as fixed ("too expensive", "impossible", "always done this way"):
1. **Ask: is this constraint physics or convention?** If it's a law of nature, accept it. If it's "how we've always done it," it's negotiable.
2. **Identify the irreducible truths** — what must be true no matter what solution you pick?
3. **Rebuild from those truths** — derive a solution that satisfies the real constraints but ignores the artificial ones. If a simpler rebuild solves it, stop.
Skip if the "why" is settled (standard library, known-good pattern). In an incident, act on the most likely cause first; reserve this for post-incident redesign.
## The Process
### Step 1: Identify Current Assumptions
List everything you "know" or assume about the problem:
- What are the constraints everyone accepts?
- What costs/limitations are considered fixed?
- What's the conventional wisdom?
- Why do people say it can't be done?
```
Example: "Rocket launches cost $65M because that's what aerospace companies charge"
Assumptions: Must buy from existing suppliers, existing designs are optimal,
materials must be aerospace-grade, vertical integration is too hard
```
### Step 2: Break Down to Fundamentals
Ask repeatedly: "What are we absolutely certain is true?"
Decomposition questions:
- What are the physical/mathematical constraints?
- What are the raw inputs required?
- What laws of physics/economics apply?
- What would this cost if built from raw materials?
- What is the minimum viable version?
```
Example: Rocket raw materials (aluminum, titanium, copper, carbon fiber)
= ~2% of typical rocket price
Fundamental truth: Materials aren't the cost driver;
manufacturing/overhead/margins are
```
### Step 3: Challenge Each Assumption
For each assumption, ask:
- Is this actually true, or just convention?
- What evidence supports this?
- Under what conditions would this be false?
- Who benefits from this assumption persisting?
Use the "5 Whys" to drill deeper:
```
Why is it expensive? → Suppliers charge high margins
Why? → Limited competition
Why? → High barriers to entry
Why? → Assumption that you must use existing supply chain
Why? → Nobody questioned it
```
### Step 4: Rebuild from Fundamentals
Starting ONLY from verified truths:
- What's the simplest solution that satisfies fundamental requirements?
- What new approaches become possible without false constraints?
- How would you solve this if starting from scratch today?
- What would a solution look like with 10x less resources?
```
Example: Build rockets in-house using commodity materials
= SpaceX reduced launch costs by 10x
```
### Step 5: Validate Against Reality
- Does your reconstructed solution violate any physics/laws?
- What practical constraints remain?
- What's the minimum viable test?
- How can you prove/disprove this quickly?
## Mental Traps to Avoid
| Trap | Description | Antidote |
|------|-------------|----------|
| Reasoning by Analogy | "Others do it this way" | Ask "but is it optimal?" |
| Appeal to Authority | "Experts say it's impossible" | "What specifically makes it impossible?" |
| Sunk Cost | "We've always done it this way" | "What if we started fresh today?" |
