A mental model for breaking down basic truths to generate original solutions. Use for innovation, novel problems, or when stuck in conventional thinking.
First Principles Thinking is a mode of inquiry that relentlessly questions assumptions to get to the fundamental truth of a problem, then builds a solution from scratch. It is the tool of the innovator, used to bypass "reasoning by analogy" (copying what others do).
When to Use This Skill
Innovation: When the user wants to invent a new way of doing things.
Stuck Points: When standard solutions are too expensive, too slow, or impossible.
Debugging: When "it should work" but doesn't—strip away assumptions about why it should work.
Cost Analysis: When you need to understand the absolute floor of a cost structure.
When NOT to Use This Skill
Well-trodden problems: When analogical reasoning is sufficient and the cost of being wrong is low.
Quantum/Biological systems: FPT assumes independence of atomic units; quantum entanglement and biological emergence violate this.
Skills relacionados
Social/Human systems: Human behavior is not decomposable into physics axioms—consult domain experts instead.
Time-critical decisions: FPT is computationally expensive; under deadline pressure, use decision-matrix or analogical reasoning.
When expertise is available: If a domain expert can be consulted and the problem is within their validated expertise, rely on their map.
Domain Boundary Checklist
Before applying FPT, confirm:
Problem is mechanical, supply-chain, or computational (not quantum/biological/social)
Atomic units are empirically verifiable (not model-dependent)
Cost of being wrong is high enough to warrant full deconstruction
Time available exceeds 2x estimated analysis duration
Skill Integration Cross-References
Before FPT: Use decision-matrix to confirm FPT is warranted (high-stakes, innovative)
After FPT: Use systems-thinking to check feedback loops and emergent behavior
Combined Protocol: When facing adversarial contexts, chain inversion-thinking → FPT
Complementary: Use rubber-ducking to verify plain-English explanation of atomic units
Avoid over-use: If FPT hits deadline frequently, the problem may be too ill-defined—consider escalating
Breaking problems down is useful (may fail for emergent systems)
Atomic units exist (may fail for quantum entanglement)
Deconstruction reveals truth (may fail for social/human systems)
Document these as explicit limits. Re-evaluate if problem domain shifts.
Examples
The SpaceX Example (Cost Reduction)
User: "Rockets are too expensive."
Analogy Reasoning: "Rockets define the market price. We can maybe save 10% by negotiating."
First Principles Reasoning: "A rocket is just aluminum, titanium, and fuel. The spot price of these materials is 2% of a rocket's cost. The cost is inefficient manufacturing. We will buy raw metal and build it ourselves."
The "Chef vs. Cook"
Analogy (Cook): Follows a recipe. If an ingredient is missing, they stop.
First Principles (Chef): Understands why the acid balances the fat. If a lemon is missing, they use vinegar, because the principle is acidity.
Self-Improvement Protocol
This skill learns to identify assumptions more accurately and find better atomic truths.
Logging Corrections
After applying First Principles Thinking:
Log to .learnings/CORRECTIONS.md:
## [YYYY-MM-DD] {Brief Description}
**Problem:** {the original problem}
**Assumption challenged:** {what was assumed}
**Breakthrough:** {the actual truth found}
**Outcome:** {did it work?}
---
Trigger Conditions
Condition
Example
Log?
Found a false assumption
"Turns out X was actually Y"
✅
Missed obvious assumption
"Should have questioned Z earlier"
✅
Wrong atomic unit
"The 'atomic' unit had substructure"
✅
Analogical reasoning was right
"Standard approach actually worked"
✅
Novel solution found
"Never seen this approach before"
✅
Pattern Categories for This Skill
Assumption patterns: Common beliefs that are usually wrong
Atomic unit types: Physics, Logic, Economics breakdowns
Questioning depth: How many "whys" needed
Analogy failures: When analogies mislead vs help
Constraint types: Physical vs logical vs economic
Review & Promote
Weekly: Check for recurring assumption patterns → Add to LEARNINGS.md