Protect the downside before chasing the upside

Ask what the worst realistic outcome is and ensure you can survive it before evaluating the upside.

Why it works

Survivability is a prerequisite for long-run compounding: a severe loss requires a disproportionately large gain to recover (a 50% loss requires a 100% gain just to break even). In life decisions, catastrophic outcomes — financial ruin, broken relationships, health collapse — compound negatively in ways that make the expected value calculation misleading unless the downside is accounted for separately.

How to do it

1. For any major decision, explicitly describe the worst realistic outcome — not the worst possible, but the plausible bad case.
2. Ask: can I survive this outcome? Is recovery possible?
3. Only proceed if the downside is survivable and the upside is large enough to justify it.
4. Treat "can I survive the downside?" as a filter that must pass before "what is the upside?" becomes relevant.

Evidence

Loss aversion research (Kahneman & Tversky) demonstrates that losses are psychologically weighted more heavily than equivalent gains. The mathematical asymmetry of percentage losses and gains makes downside protection rational on pure expected-value grounds, independent of loss aversion. (observational)

Excessive downside focus can lead to excessive risk aversion; the goal is to ensure survivability, not to eliminate all downside risk.

Sources

• Kahneman & Tversky (1979), prospect theory, Econometrica

Common mistake

Evaluating the upside first and letting the excitement of it crowd out a sober assessment of the downside — the order of analysis matters.