Circle of Competence, explained.
A circle of competence is the boundary of situations whose economics and uncertainties a decision maker can evaluate. Buffett's formulation emphasises knowing that boundary rather than making it as large as possible.
Why it happens
An honest uncertainty range exposes possible adverse outcomes. A familiar model can have a narrower range, but price still matters and unfamiliar does not mean automatically worthless. Passing avoids a purchase without guaranteeing that its realised value would have been poor.
A circle of competence is the set of situations whose economics and uncertainties a decision maker understands well enough to evaluate. Knowing the boundary matters more than confidently claiming universal expertise.
Read the result
Review six offers, choose Buy or Pass, and read the revealed value and ledger. Compare worst-case net gain with expected value before choosing. The supplied uniform ranges are reliable teaching information, an advantage real investors rarely possess.
A worked example
A narrow range and a low ask
A fictional familiar deal has a stated value range of eighty to 120 and an asking price of seventy.
Every value in that supplied range exceeds the ask, while a different ask of 110 would allow a loss.
The label familiar is unchanged, but the price changes the decision. In the real world, scrutinise whether the range itself deserves confidence.
OPTIONAL DEEPER DETAILGo deeper: inside the model
Inside this model
Six seeded deals alternate stated value ranges of 80–120 and 30–170 tokens. Values are sampled uniformly within the range; asks range from 70 to 130. One unit can be bought or passed per card. Realised net gain accumulates and each decision remains visible in a ledger.
Where this idea is useful
A practical use
A narrower range can support a robust price comparison, but even an unfamiliar offer may be attractive under a sufficiently low price and explicitly stated assumptions.
A common misconception
“A familiar business must be a safe purchase at any price.”
Understanding a business does not remove valuation, financing, or operational risk. Competence supports evaluation; it does not erase the price paid or guarantee an outcome.
What this explanation leaves out
- The game supplies reliable ranges and probabilities that real investors seldom know. Passing does not guarantee a better realised result, and familiar is not the same as safe. It does not evaluate a real person's competence.
Does a missed profitable offer prove that passing was wrong?
A realised outcome alone does not determine the quality of a decision under uncertainty. Compare the evidence and possible outcomes available at the time.
Where can you explain the downside from evidence, and where are you borrowing confidence from a familiar story?
Associated thinkers
Associations marked provisional are awaiting source review.
Further reading
Explore the original research or the teaching reference behind this experiment.