Psychology & Behavior
ProSunk Cost Check
沉沒成本檢查 · Source: Richard Thaler / Daniel Kahneman
Detecting whether you're continuing something you shouldn't — because of what you've already invested
Core Concept
The sunk cost fallacy: continuing to invest because of what you've already spent — even when rational analysis says stop. "I've already put so much into this" is a dangerous rationale. Past costs are irrecoverable. The only thing that matters is future expected value.
✓ When to use this
When you consider continuing because "I have already invested so much." For projects, relationships, degrees, investments — time and money already spent are past tense, irrelevant to whether continuing is worthwhile now.
✗ When not to use this
Near-completion situations where remaining cost is less than completion value — continuing is rational, not a sunk-cost trap. Also unsuitable for relationships or moral commitments where commitment ethics matters, not pure accounting.
Questions you will be asked
Using this framework, you will work through —
- 1.What are you considering whether to continue?
- 2.What have you already invested? (Time, money, emotion, opportunity cost)
- 3.Key question: If you were encountering this opportunity for the first time today, would you choose to invest?
- …and 3 more
Related Frameworks
Investment & Finance
Commitment Escalation Check
Detecting whether you're escalating commitment to a failing bet — justified only by "I've invested too much"
Investment & Finance
Opportunity Cost Framework
Resource allocation decisions — how to deploy time, money, attention; especially when you're treating "do nothing" as a free option
Psychology & Behavior
Loss Aversion Check
Distinguishing between genuine risk assessment and your brain's irrational fear of loss