Model Router
Overview
This is the master routing skill for all mental models. Instead of knowing 38 frameworks, start here. Identify your domain and problem type, and this skill points you to the right model(s). Think of it as the "which tool do I use?" guide.
Core Principle: Don't memorize models—memorize how to find the right one. Domain + Problem Type → Model.
Quick Router
Step 1: What's Your Domain?
| Domain | You're working on... |
|---|---|
| Coding/Debugging | Bugs, errors, performance issues, root cause |
| Architecture | System design, technical decisions, scalability |
| Product | Features, user needs, prioritization, roadmap |
| Business Strategy | Competition, growth, market, organization |
| Personal Decisions | Career, life choices, major commitments |
| Abstract/Analytical | Arguments, ideas, theories, pure reasoning |
| Risk/Safety | What could go wrong, preparation, resilience |
| Innovation | New ideas, breakthroughs, creative solutions |
Step 2: What's Your Problem Type?
| Type | You need to... |
|---|---|
| Diagnose | Find root cause, understand why |
| Decide | Choose between options |
| Understand | Grasp how something works |
| Create | Generate new solutions |
| Evaluate | Judge quality or validity |
| Predict | Forecast outcomes |
| Optimize | Improve performance |
Domain → Model Maps
🖥️ Coding & Debugging
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PROBLEM → MODEL(S) ───────────────────────────────────────────────────── Bug with unknown cause → Scientific Method, 5 Whys Plus Performance degradation → Theory of Constraints, Systems Thinking Spans multiple services → Systems Thinking, Feedback Loops Incident postmortem → 5 Whys Plus, Systems Thinking Flaky/intermittent behavior → Scientific Method (hypothesis testing) "It works on my machine" → Map-Territory (model vs reality gap)
Default for debugging: Start with 5 Whys Plus, escalate to Systems Thinking if it spans components.
🏗️ Architecture & Technical Decisions
code
PROBLEM → MODEL(S) ───────────────────────────────────────────────────── Technology choice → Lindy Effect, Reversibility Build vs buy → Opportunity Cost, First Principles Scalability design → Systems Thinking, Leverage Points Microservices vs monolith → Cynefin, Reversibility Database selection → Lindy Effect, Theory of Constraints API design tradeoffs → TRIZ (resolve contradictions) Should we rewrite? → Second-Order, Opportunity Cost
Default for architecture: Start with Reversibility (is this Type 1 or Type 2?), then Systems Thinking for interconnections.
📦 Product & Feature Development
code
PROBLEM → MODEL(S) ───────────────────────────────────────────────────── What should we build? → Jobs to be Done Feature prioritization → Opportunity Cost, Theory of Constraints Why aren't users engaging? → Jobs to be Done, 5 Whys Plus New product exploration → Effectuation, First Principles Should we pivot? → Regret Minimization, Reversibility Product-market fit → Jobs to be Done, Scientific Method Roadmap planning → Theory of Constraints, Opportunity Cost A/B test design → Scientific Method, Bayesian
Default for product: Start with Jobs to be Done (what job is the user hiring this for?).
📈 Business Strategy
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PROBLEM → MODEL(S) ───────────────────────────────────────────────────── Competitive analysis → Red Team, Second-Order Market entry → Cynefin, Effectuation Growth strategy → Feedback Loops, Leverage Points Organizational dysfunction → Archetypes, Systems Thinking Resource allocation → Theory of Constraints, Opportunity Cost Startup strategy → Effectuation, Margin of Safety M&A evaluation → Pre-mortem, Steel-manning Pricing decisions → First Principles, Fermi Estimation
Default for strategy: Start with Cynefin (what domain is this problem in?), then match approach.
🧑 Personal & Career Decisions
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PROBLEM → MODEL(S) ───────────────────────────────────────────────────── Should I take this job? → Regret Minimization, Reversibility Career direction → Circle of Competence, Regret Minimization Major life decision → Regret Minimization, Pre-mortem Learning what to learn → Circle of Competence, Lindy Effect Negotiation prep → Steel-manning, Red Team Should I start a company? → Effectuation, Margin of Safety, Pre-mortem Time allocation → Opportunity Cost, Theory of Constraints
Default for personal: Start with Regret Minimization (what will 80-year-old you think?).
🧠 Abstract & Analytical Thinking
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PROBLEM → MODEL(S) ───────────────────────────────────────────────────── Evaluating an argument → Steel-manning, Bayesian Challenging assumptions → First Principles, Socratic Estimating unknowns → Fermi Estimation, Probabilistic Updating beliefs → Bayesian, Probabilistic Exploring edge cases → Thought Experiment, Inversion Finding logical flaws → Inversion, Steel-manning Complex causation → Systems Thinking, Feedback Loops Philosophical questions → Thought Experiment, First Principles
Default for abstract: Start with Steel-manning (argue the strongest opposing view first).
⚠️ Risk & Safety
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PROBLEM → MODEL(S) ───────────────────────────────────────────────────── What could go wrong? → Pre-mortem, Red Team Security review → Red Team, Inversion Disaster preparation → Pre-mortem, Margin of Safety Avoiding catastrophic failure → Margin of Safety, Via Negativa Stress-testing plans → Red Team, Pre-mortem Probability of failure → Probabilistic, Bayesian Building resilience → Via Negativa, Margin of Safety
Default for risk: Start with Pre-mortem (assume failure, explain why).
💡 Innovation & Creativity
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PROBLEM → MODEL(S) ───────────────────────────────────────────────────── Breakthrough needed → First Principles, TRIZ Stuck on contradictions → TRIZ Limited resources → Effectuation, Via Negativa Simplification → Via Negativa, Occam's Razor Challenging "impossible" → First Principles, TRIZ New market creation → Effectuation, Jobs to be Done Removing complexity → Via Negativa, Occam's Razor
Default for innovation: Start with First Principles (strip to fundamentals, rebuild).
Quick Reference Card
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┌─────────────────────────────────────────────────────────────────┐ │ MENTAL MODEL QUICK ROUTER │ ├─────────────────────────────────────────────────────────────────┤ │ │ │ "Why is this broken?" → 5 Whys Plus, Scientific Method │ │ "How does this system work?" → Systems Thinking, Feedback Loops│ │ "What should we build?" → Jobs to be Done │ │ "Should I do this?" → Reversibility, Regret Min │ │ "What could go wrong?" → Pre-mortem, Red Team │ │ "How do I innovate?" → First Principles, TRIZ │ │ "What's the probability?" → Bayesian, Probabilistic │ │ "Where's the bottleneck?" → Theory of Constraints │ │ "What am I giving up?" → Opportunity Cost │ │ "Is this argument valid?" → Steel-manning │ │ "Will this technology last?" → Lindy Effect │ │ "How complex is this?" → Cynefin │ │ "What to remove?" → Via Negativa │ │ "Is this safe enough?" → Margin of Safety │ │ │ └─────────────────────────────────────────────────────────────────┘
Decision Flow
code
START HERE
│
▼
┌─────────────────────┐
│ What's your domain? │
└──────────┬──────────┘
│
┌─────┴─────┬──────────┬──────────┬──────────┐
▼ ▼ ▼ ▼ ▼
Coding Architecture Product Strategy Personal
│ │ │ │ │
▼ ▼ ▼ ▼ ▼
┌─────────────────────┐
│ What problem type? │
│ Diagnose/Decide/ │
│ Understand/Create/ │
│ Evaluate/Predict │
└──────────┬──────────┘
│
▼
┌─────────────────────┐
│ Look up in domain │
│ table above │
└──────────┬──────────┘
│
▼
┌─────────────────────┐
│ Single model enough?│
└──────────┬──────────┘
│
┌──────┴──────┐
▼ ▼
YES NO
│ │
▼ ▼
Apply it Use Model Combination
(Sequential/Parallel/Nested)
Model Inventory by Category
Diagnostic Models (Find root cause)
- •
5 Whys Plus- Iterative "why" with bias guards - •
Scientific Method- Hypothesis → Test → Learn - •
Kepner-Tregoe- Systematic problem/decision analysis
Decision Models (Choose wisely)
- •
Reversibility- Type 1 vs Type 2 decisions - •
Regret Minimization- What will future-you think? - •
Opportunity Cost- What are you giving up? - •
Bayesian- Update beliefs with evidence - •
Probabilistic- Calibrated probability estimates
Systems Models (Understand interconnections)
- •
Systems Thinking- Feedback, emergence, non-linearity - •
Feedback Loops- Reinforcing and balancing loops - •
Theory of Constraints- Find and exploit the bottleneck - •
Leverage Points- Where small changes have big effects - •
Archetypes- Recurring system patterns
Risk Models (Prepare for failure)
- •
Pre-mortem- Assume failure, explain why - •
Red Team- Attack your own plan - •
Margin of Safety- Build in buffers - •
Inversion- Identify paths to failure, avoid them
Innovation Models (Create breakthroughs)
- •
First Principles- Strip to fundamentals, rebuild - •
TRIZ- Resolve technical contradictions - •
Effectuation- Start with means, not goals - •
Via Negativa- Improve by removing
Evaluation Models (Judge quality)
- •
Steel-manning- Argue strongest opposing view - •
Lindy Effect- Older = likely to last longer - •
Circle of Competence- Know your expertise boundaries - •
Occam's Razor- Prefer simpler explanations
Context Models (Match approach to situation)
- •
Cynefin- Clear/Complicated/Complex/Chaotic domains - •
Model Selection- Choose the right model - •
Model Combination- Use multiple models together
Product Models (Build the right thing)
- •
Jobs to be Done- What job is user hiring this for? - •
Thought Experiment- Structured imagination
Estimation Models (Size unknowns)
- •
Fermi Estimation- Order-of-magnitude calculations
When to Combine Models
Use Model Combination when:
| Situation | Combination Pattern | Example |
|---|---|---|
| High-stakes decision | Sequential | Reversibility → Pre-mortem → Opportunity Cost |
| System diagnosis | Nested | Cynefin (macro) → ToC (meso) → OODA (micro) |
| Validating strategy | Parallel | Red Team + Steel-manning + Second-Order |
| Innovation under constraints | Sequential | First Principles → TRIZ → Effectuation |
| Career decision | Temporal | 5 Whys (past) → Circle of Competence (present) → Regret Min (future) |
Template
markdown
# Model Router Analysis ## Context Domain: [Coding/Architecture/Product/Strategy/Personal/Abstract/Risk/Innovation] Problem: [Brief description] Problem Type: [Diagnose/Decide/Understand/Create/Evaluate/Predict/Optimize] ## Routed Models Primary: [Main model to use] Secondary: [If needed] Combination pattern: [Sequential/Parallel/Nested/None] ## Application [Apply the selected model(s) here] ## Verification - [ ] Domain correctly identified - [ ] Problem type matches - [ ] Model fits the situation - [ ] Considered if combination needed
Key Questions
- •"What domain am I operating in?"
- •"What type of problem is this—diagnose, decide, understand, create, or evaluate?"
- •"What's the default model for this domain + type?"
- •"Does one model cover it, or do I need to combine?"
- •"Am I using a model because it fits, or because it's familiar?"
Remember: You don't need to know all 38 models. You need to know how to find the right one. Start with domain, identify problem type, look it up, apply. That's it.