Investment & Finance
Margin of Safety Thinking
安全邊際思考 · Source: Benjamin Graham / Warren Buffett
Any decision resting on critical assumptions — investments, ventures, major commitments — ensuring you survive when assumptions prove wrong
Core Concept
If your critical assumptions are off by 30%, does the decision still hold? Margin of safety isn't pessimism — it's acknowledging forecast uncertainty and building in enough buffer so you're not eliminated when things go wrong.
✓ When to use this
For any decision with potential irreversible loss: investment sizing, startup cash runway, career-change savings buffer, health-related risk exposure. Mandatory when failure cost dwarfs success upside.
✗ When not to use this
Adding a margin to low-risk, high-frequency choices forfeits compounding — e.g. small daily life calls. In highly competitive arenas, over-conservatism also loses to those who shoulder risk.
Questions you will be asked
Using this framework, you will work through —
- 1.What decision are you considering?
- 2.What three critical assumptions must hold for this decision to work?
- 3.If each assumption is off by 20-30%, does the decision still hold?
- …and 3 more
Related Frameworks
Investment & Finance
Expected Value Analysis
Decisions with quantifiable outcomes — investments, business decisions, choices with probability and payoff structures
Management & Thinking
Pre-mortem
Stress-testing a plan before committing — finding failure paths you haven't seen yet
Management & Thinking
Inversion
Finding "how to guarantee failure" in order to reverse-engineer "how to guarantee success"