TWO BETS
When Uncertainty Pays You
A field rule for uncertain bets: size the total loss to survive, keep the upside genuinely open, pay the carrying cost, then test the curve over the relevant domain.
JENSEN
The chord is the test; a real bend can lift expected value
This is the actual convexity test over the relevant domain. Capped loss plus open upside neither proves convexity nor is required for it; those terms describe a practical asymmetric profile.
- Jensen, Acta Mathematica 30 (1906), pages 175-193
- For convex f: f(lambda x + (1-lambda)y) <= lambda f(x) + (1-lambda)f(y)
- The gain is strict only where the payoff actually bends
Terms screen the bet; curvature tests convexity; odds price it
Use probabilities where a reliable reference class exists. A loss cap and open upside screen for practical asymmetry, not mathematical convexity. Test curvature separately: over the relevant domain, the payoff at every weighted-average state must not exceed the same weighted average of endpoint payoffs.
THE BARBELL
Safe mass, wild slice, no middle
- 01Taleb, Antifragile (2012), chapter 11: keep the bulk low-risk and liquid
- 02Cut a slice you can lose entirely
- 03Scatter that slice across many open-ended bets
- 04Avoid the deceptively stable middle
Source: Taleb, Antifragile (2012), chapter 11, "Never Marry the Rock Star," section "Seneca's Barbell."
AFFORDABLE LOSS
Write off the whole stake before you start
- Sarasvathy, Academy of Management Review 26(2), 2001, page 252, doi:10.2307/259121
- Count cash, time, attention, guarantees, and reputation
- A capacity cap or partner veto cuts the ceiling, not the loss floor
Affordable loss is a sizing rule, not a curvature test. Sarasvathy states the principle on page 252: predetermine what loss is affordable. If total failure leaves you unable to try again, the stake was never affordable.
THE TURN
The curve works in clear weather; the rule earns its keep in fog
- Black & Scholes, Journal of Political Economy 81(3), 1973, pages 637-654
- Knight, Risk, Uncertainty and Profit (1921), Part III, chapter VII
- Known odds: price them. No reliable class: do not invent them
Knightian uncertainty is where no reliable reference class is available. Convexity does not create odds there. Affordable-loss sizing limits what a bad estimate can cost; curvature separately tells you whether dispersion can help.
BRING A VERIFIER
Price the proof into the bet
- Gross upside minus checking cost equals collectible upside
- Count verification time against the expiry clock
- A convex curve can still be a bad trade after checking cost
Verification has its own economics. For sizing, count the full cost of checking before you call the upside open.
Expiry turns attention into a carrying cost
Bowman and Hurry, Academy of Management Review 18(4), 1993, page 763: a shadow option must first be recognised before it can be struck. For sizing, fund the monitoring before the right expires unseen.