The core principle — prefer simplicity
❌ Complex explanation
Hypothesis A
→ assumes X → assumes Y → assumes Z
Sub-theory 1
needs proof
Sub-theory 2
needs proof
⚠ Fragile — fails if any single assumption breaks
✓ Simple explanation
Hypothesis B
→ fits the facts directly
- Fewer assumptions
- Easier to falsify
- Harder to hide errors
- Prefer this unless evidence demands complexity
Applying it — the razor test
The Razor Test
Ask
"What's the simplest explanation that fits?"
→
If simpler fits…
Extra complexity needs explicit justification
burden of proof shifts to complexity
→
Prefer the simpler
Explanation and act on it with confidence
How Munger applied it
Investing
Skip complex valuation models. Ask one question: does this business earn high returns on capital durably? If yes and cheap — buy. If no — pass.
See's Candies test: simple moat, simple math, simple yes.
Business Models
Distrust complexity that obscures fees, incentives, or incompetence. If you can't explain the business model simply, something is being hidden — deliberately or not.
derivatives warning: complexity = hidden risk
Decisions
One-sentence test: if you can't state the reason for a decision simply and clearly, you probably don't understand it well enough to act on it.
clarity = understanding · confusion = danger
⚠ The limit — when NOT to razor
Reality is sometimes genuinely complex — evolution, markets, geopolitics. Occam's Razor is a starting bias, not a final answer. It tells you to begin with the simpler explanation and demand evidence before adding complexity — not to deny that complexity exists.
oversimplify → wrong model → costly errors. The razor cuts both ways.
"
I have a simpler set of rules. I don't use the Black-Scholes model. I don't use the Capital Asset Pricing Model. I don't use Modern Portfolio Theory. They're all too complicated and too likely to be wrong. I just ask: is this a good business at a fair price? That's about it.
— Charlie Munger, various interviews