---
name: first-principles-thinker
description: |
  Breaking problems down to their fundamental truths and reasoning up from there. Covers Socratic questioning, assumption identification, reasoning from ground truth, practical application methods, innovation through first principles, physics thinking, and structured practice exercises for developing first-principles reasoning ability. Use when the user asks about first principles thinker or needs help with related topics. Do NOT use for unrelated domains or when a more specialized skill exists.
license: Apache-2.0
metadata:
  author: foundry-skills
  version: "1.0.0"
  tags: "decision-making analysis strategy frameworks"
  category: "productivity"
  subcategory: "methodology-frameworks"
  depends: ""
  disclaimer: "none"
  difficulty: "advanced"
---

# First Principles Thinker

## When to Use


## Process

1. **Gather requirements.** Ask the user clarifying questions about their specific context, goals, constraints, and experience level.

2. **Analyze the situation.** Review the information provided and identify key factors, challenges, and opportunities relevant to first principles thinker.

3. **Develop the framework.** Create a structured approach tailored to the user's needs, incorporating best practices and domain-specific considerations.

4. **Deliver actionable output.** Present specific, implementable recommendations with clear rationale, timelines, and success criteria.

5. **Address edge cases.** Proactively identify potential issues, alternative approaches, and contingency plans.

**Use this skill when:**
- User needs guidance on first principles thinker
- User asks about first principles thinker best practices or techniques
- User wants a structured approach to first principles thinker

**Do NOT use this skill when:**
- A more specialized skill exists for the specific subtopic
- The request is outside the scope of first principles thinker

## Questions to Ask First

Before applying first-principles thinking to any problem, clarify:

1. **What is the problem or question you are trying to solve?** (State it precisely)
2. **What is the current approach or conventional wisdom?** (What does everyone assume)
3. **Why are you questioning it?** (Dissatisfaction with results, seeking innovation, cost reduction, curiosity)
4. **What constraints are truly fixed vs. assumed?** (Physics, regulations, budget, or just habit)
5. **What would the ideal outcome look like if nothing were given?** (Unconstrained vision)
6. **What domain is this in?** (Technology, business, personal, science, design)
7. **What resources do you have for experimentation?** (Time, money, expertise)

## What First Principles Thinking Is

```
DEFINITION:
  First principles thinking is the practice of breaking down
  a problem into its most fundamental truths -- things that
  cannot be reduced further -- and then reasoning upward from
  those foundations to build new solutions.

CONTRAST WITH REASONING BY ANALOGY:
  Analogy: "Other companies charge $X, so we should charge around $X."
  First Principles: "What does it actually cost us to deliver this?
    What value does it actually create? What would a customer pay
    based on that value alone?"

  Analogy: "Batteries are expensive because they've always been expensive."
  First Principles: "What are batteries made of? What do those raw
    materials cost on the commodities market? What is the minimum
    cost to assemble them? The gap between that and the current price
    is the opportunity."

WHY IT MATTERS:
  - Analogy-based thinking leads to incremental improvement
  - First-principles thinking enables breakthrough innovation
  - Most "impossible" problems are only impossible within assumed constraints
  - The biggest competitive advantages come from questioning what
    everyone else takes for granted
```

## The Socratic Questioning Method

### The Five Types of Socratic Questions

```
1. CLARIFYING QUESTIONS (Understand the basics)
   "What exactly do you mean by...?"
   "Can you give me an example?"
   "What is the core of this problem?"
   "How would you state this more precisely?"

2. PROBING ASSUMPTIONS (Challenge what's taken for granted)
   "What are we assuming here?"
   "Why do we believe that to be true?"
   "What would happen if that assumption were wrong?"
   "Is this always the case, or are there exceptions?"
   "What evidence supports this assumption?"

3. PROBING EVIDENCE AND REASONING (Test the logic)
   "How do we know this?"
   "What data supports this conclusion?"
   "Is there a counterexample?"
   "Is this correlation or causation?"
   "What would change your mind?"

4. QUESTIONING VIEWPOINTS AND PERSPECTIVES (Consider alternatives)
   "How would someone who disagrees see this?"
   "What would a newcomer to this industry do?"
   "How would this look from the customer's perspective?"
   "What would happen if we approached this from the opposite direction?"

5. PROBING IMPLICATIONS AND CONSEQUENCES (Follow the chain)
   "If this is true, what else must be true?"
   "What are the second-order effects?"
   "What are the unintended consequences?"
   "What would this mean in practice?"
   "If we follow this logic to its conclusion, where does it lead?"
```

### Applied Socratic Questioning Example

```
PROBLEM: "We need to hire more customer support agents."

CLARIFYING:
  Q: "Why do we need more agents?"
  A: "Response times are too long -- averaging 4 hours."

PROBING ASSUMPTIONS:
  Q: "Are we assuming that more agents is the only way to reduce
      response time?"
  A: "Well... it's how we've always done it."

  Q: "What's actually causing the long response times?"
  A: "Volume is up 40% from last year."

  Q: "Is all that volume necessary? Why are customers contacting us?"
  A: "60% of tickets are about the same 5 issues."

PROBING EVIDENCE:
  Q: "If 60% of contacts are about 5 known issues, what would
      happen if we fixed those issues or provided self-service answers?"
  A: "Volume would drop by more than half."

IMPLICATIONS:
  Q: "So the first principle isn't 'we need more agents' but
      'customers have problems that shouldn't exist or should be
      solvable without human intervention'?"
  A: "That reframes everything."

RESULT: Instead of hiring 10 agents ($500K/year), they fixed the
top 5 product issues and built a knowledge base ($50K), reducing
volume by 55% and response times to under 1 hour.
```

## The First Principles Process

### Step 1: Identify and Question Assumptions

```
THE ASSUMPTION AUDIT:

Take your current belief, plan, or approach and list every
assumption embedded in it.

EXAMPLE: "We should build a mobile app."
  Assumption 1: Our users want a mobile app
  Assumption 2: A native app is better than a mobile website
  Assumption 3: We have the resources to build and maintain it
  Assumption 4: An app will increase engagement
  Assumption 5: The app stores are the right distribution channel
  Assumption 6: Users will download yet another app
  Assumption 7: The features we plan justify a separate app

FOR EACH ASSUMPTION, ASK:
  - Is this demonstrably true? What is the evidence?
  - Is this a law of nature, or a convention?
  - Who benefits from this assumption being unchallenged?
  - What would change if this assumption were false?
  - When did this become true, and is it still true?

ASSUMPTION CATEGORIES:
  PHYSICS: Cannot be violated (gravity, thermodynamics, speed of light)
  LEGAL: Can be changed but requires regulatory process
  ECONOMIC: Market forces that may shift
  CONVENTIONAL: "The way things are done" -- most challengeable
  PSYCHOLOGICAL: Human nature -- deep but not always as fixed as assumed
```

### Step 2: Break Down to Fundamentals

```
THE DECOMPOSITION METHOD:

Take the problem and keep asking "What is this made of?"
until you reach irreducible components.

EXAMPLE: "Electric car batteries are too expensive."

Layer 1: What is a battery made of?
  -> Cathode, anode, separator, electrolyte, casing, electronics

Layer 2: What are those made of?
  -> Lithium, nickel, cobalt, manganese, aluminum, copper, graphite

Layer 3: What do those materials cost?
  -> Check commodity prices on the London Metal Exchange
  -> Total raw material cost for a 60kWh battery: ~$3,000-4,000

Layer 4: What is the current retail cost?
  -> $8,000-12,000

Layer 5: Where is the gap?
  -> Manufacturing process, margin stacking, supply chain inefficiency

FUNDAMENTAL TRUTH:
  The materials cost $3-4K. If you can build a more efficient
  manufacturing process, you can dramatically reduce the price.
  (This is essentially what Tesla did with battery production.)

THE DECOMPOSITION TEMPLATE:
  Problem: _______________
  What is it made of? _______________
  What do those components actually cost/require? _______________
  What is the current cost/state? _______________
  Where is the gap? _______________
  What creates that gap? _______________
  Which gap-creators are fundamental vs. conventional? _______________
```

### Step 3: Reason Up from Fundamentals

```
THE RECONSTRUCTION METHOD:

Once you have fundamental truths, build a new solution from scratch.

RULES FOR RECONSTRUCTION:
  1. Only use verified fundamental truths as building blocks
  2. Do not import assumptions from the existing solution
  3. Ask "What is the simplest way to achieve this?" at each step
  4. Challenge any constraint that is not a law of physics
  5. Consider all possible configurations, not just familiar ones

EXAMPLE: "How should people learn?"

  Fundamental truths about learning:
  - Humans learn by doing (active recall > passive review)
  - Spaced repetition dramatically improves retention
  - Immediate feedback accelerates learning
  - Motivation comes from progress visibility and autonomy
  - Different people learn at different paces
  - Context and emotional connection aid memory

  Reconstructing from fundamentals:
  -> Learning should be active, not passive (not lectures)
  -> Material should be spaced over time (not crammed)
  -> Feedback should be immediate (not weeks later)
  -> Progress should be visible and personal
  -> Pace should adapt to the individual
  -> Content should connect to real-world context

  This describes adaptive learning software more than it
  describes a traditional classroom. The fundamentals lead
  to a very different solution than convention.
```

### Step 4: Validate and Iterate

```
VALIDATION FRAMEWORK:

Once you've built a new solution from fundamentals, test it:

1. LOGICAL CHECK: Does this follow from the fundamentals?
   Walk through the reasoning chain. Is each step valid?

2. PRACTICAL CHECK: Can this actually be built/implemented?
   What resources, technology, or capabilities are needed?
   What is the minimum viable version?

3. ECONOMIC CHECK: Is this viable at the required scale?
   What are the unit economics from first principles?

4. EMPIRICAL CHECK: Does this work in practice?
   Build the smallest possible test and measure results.
   What would disprove this approach?

5. COMPETITIVE CHECK: If this is so obvious from fundamentals,
   why hasn't someone done it already?
   - Maybe they have (research more)
   - Maybe the fundamentals were recently changed (new technology)
   - Maybe convention is too strong (opportunity)
   - Maybe there's a hidden constraint you missed (investigate)
```

## Real-World Applications

### Elon Musk's Battery Cost Example

```
CONVENTIONAL WISDOM (2006):
  "Batteries cost $600/kWh. That's just what they cost.
   Electric cars will always be too expensive."

FIRST PRINCIPLES:
  Musk asked: "What are batteries made of? What is the spot
  market value of the material constituents?"

  Answer: Carbon, nickel, aluminum, some polymers for separation,
  and a steel can. On the London Metal Exchange, these cost
  roughly $80/kWh.

  Gap: $600 vs $80 = $520 of manufacturing overhead and margin

  Question: "Can we build a factory that closes this gap?"

  Result: Tesla Gigafactory drove costs from $600 to under $140/kWh
  by 2023, making electric vehicles commercially viable.
```

### SpaceX Rocket Reusability

```
CONVENTIONAL WISDOM:
  "Rockets are disposable. You can't reuse them.
   That's just how space works."

FIRST PRINCIPLES:
  "What is a rocket made of?" -> Aluminum, titanium, copper, carbon fiber
  "What do these materials cost?" -> ~2% of the total rocket cost
  "So 98% of the cost is manufacturing and assembly, not materials."
  "What if we could reuse the manufactured rocket?"
  "Is there a physical law preventing rocket landing?" -> No
  "What engineering challenges exist?" -> Propulsion, guidance, structural
  "Are these solvable?" -> Yes, with sufficient engineering effort

  Result: Falcon 9 boosters now land and fly again, reducing
  launch costs by ~10x.
```

### Personal Finance Example

```
CONVENTIONAL WISDOM:
  "You need a 20% down payment to buy a house."

FIRST PRINCIPLES:
  What do you actually need to live somewhere?
  -> Shelter, in a location near work/life

  What are all the ways to get shelter?
  -> Buy, rent, co-living, house hack, build, tiny home, mobile home,
     live on a boat, negotiate employer housing, house-sit

  What does ownership actually provide vs. renting?
  -> Equity building, tax benefits, customization, stability
  -> But also: maintenance, illiquidity, transaction costs, risk

  What is the actual mathematical comparison in YOUR situation?
  -> [Run the numbers with real data for your location, income, timeline]

  First principles answer: The right choice depends entirely on your
  specific numbers, not on the cultural assumption that "buying is better."
```

## Physics Thinking

```
APPLYING PHYSICS REASONING TO NON-PHYSICS PROBLEMS:

1. CONSERVATION LAWS: What is conserved in this system?
   In any transaction, value must come from somewhere.
   "If this seems too good to be true, what's the hidden cost?"

2. ENTROPY: Systems tend toward disorder without energy input
   Organizations naturally become more complex and bureaucratic.
   Simplification requires active, ongoing effort.

3. FEEDBACK LOOPS: What reinforces or dampens the system?
   Positive feedback: Growth creates more growth (until limits)
   Negative feedback: Correction mechanisms that stabilize

4. DIMENSIONAL ANALYSIS: Do the units work out?
   "We'll grow revenue 50% by increasing conversion 2%."
   Check: Does a 2% conversion improvement actually yield 50% revenue?
   (Often the math doesn't support the narrative.)

5. BOUNDARY CONDITIONS: What happens at the extremes?
   "What if we had 0 customers? What if we had 10 million?"
   Extreme cases often reveal hidden assumptions.

6. SYMMETRY: If this works in one direction, does it work in reverse?
   "If A causes B, does removing A remove B?"
   (Often not -- which reveals the real causal structure.)
```

## Common Traps in First Principles Thinking

```
TRAP 1: GOING TOO DEEP
  You can decompose anything to quantum physics, but that's
  not useful. Stop decomposing when you reach truths that are
  verifiable and actionable for your problem.

TRAP 2: IGNORING VALID CONVENTIONS
  Not all conventions are wrong. Many exist for good reasons.
  First principles thinking should be applied selectively to
  high-impact questions, not to every daily decision.

TRAP 3: CONFUSING YOUR OPINION WITH A FUNDAMENTAL TRUTH
  "People want X" is rarely a fundamental truth.
  "People have need Y" is more likely fundamental.
  Test your "fundamentals" rigorously.

TRAP 4: UNDERESTIMATING IMPLEMENTATION
  A brilliant first-principles solution that can't be built is
  worthless. Physics allows it; engineering (and economics and
  politics) must also allow it.

TRAP 5: ANALYSIS PARALYSIS
  First principles thinking takes time and energy. Use it for
  decisions that justify the investment. For routine decisions,
  heuristics and analogy are more efficient.

WHEN TO USE FIRST PRINCIPLES:
  - The existing solution seems unnecessarily complex or expensive
  - You're entering a new domain without preconceptions
  - You're trying to achieve a 10x improvement (not 10%)
  - Everyone says "that's just how it works"
  - The stakes justify the time investment

WHEN ANALOGY IS FINE:
  - The problem is well-understood and routine
  - You need a quick decision with low stakes
  - The domain hasn't fundamentally changed
  - You're learning (analogy helps build initial understanding)
```

## Practice Exercises

### Exercise 1: Assumption Audit
Take a major decision you've recently made or a current plan. List every assumption embedded in it (aim for at least 10). For each, ask: "Is this a fundamental truth or a convention?" Challenge at least 3 conventions.

### Exercise 2: Cost Decomposition
Pick any product or service you use. Break down its cost to raw components. What are the materials and labor actually worth? Where is the markup? Is there an opportunity?

### Exercise 3: Reverse Engineering
Take a successful company or product. Work backwards: What fundamental truths did they build on? What conventions did they reject? What assumptions did competitors make that they didn't?

### Exercise 4: Constraint Removal
State a problem you're facing. List every constraint. Categorize each as physics (unchangeable), regulatory (changeable with effort), or conventional (changeable by choice). Remove the conventional constraints and design a solution.

### Exercise 5: The "Why?" Chain
Pick any accepted practice in your work or industry. Ask "Why?" five times in succession, each time going deeper. Document where the reasoning chain leads and what assumptions surface.

### Exercise 6: New Domain Problem
Take a problem from an industry you know nothing about. Apply the full first-principles process (identify assumptions, decompose, reconstruct). Compare your solution to what experts do. The differences are often instructive.

## Integration with Other Mental Models

```
FIRST PRINCIPLES + INVERSION:
  Instead of "How do we succeed?" ask "What would guarantee failure?"
  Then ensure those fundamentals are addressed.

FIRST PRINCIPLES + SECOND-ORDER THINKING:
  After rebuilding from fundamentals, trace the consequences
  two and three steps out. What ripple effects does the new
  approach create?

FIRST PRINCIPLES + SYSTEMS THINKING:
  Understand that your fundamental truths exist within a system.
  Changing one fundamental may shift the entire system's behavior
  in unexpected ways.

FIRST PRINCIPLES + BAYESIAN REASONING:
  Use first-principles analysis to form your prior probability.
  Then update with empirical evidence as you test and learn.
```


## Output Format

Deliver the response as a structured document with clear headings and actionable content. Use tables for comparisons, numbered lists for sequential steps, and bullet points for options. Include specific examples where applicable.

```
[First Principles Thinker deliverable]
1. Context and objectives
2. Analysis or framework
3. Specific recommendations with rationale
4. Action items with timeline
```


## Example

**Input:** "Help me with first principles thinker for a mid-size project."

**Output:** A complete first principles thinker framework tailored to the specific context, with actionable steps, relevant considerations, and measurable outcomes.


## Edge Cases

- **Incomplete information:** Ask clarifying questions before proceeding rather than making assumptions
- **Conflicting requirements:** Identify trade-offs explicitly and present options with pros and cons
- **Scale mismatch:** Adapt recommendations to match the user's context (individual vs. team vs. organization)
- **Domain crossover:** When the request overlaps with other skill domains, address what falls within scope and reference specialized skills for the rest
