Decision pattern comparison
Sunk Cost Fallacy vs. Escalation of Commitment
They often appear together, but they are not interchangeable. One describes the backward-looking reason. The other describes the repeated behavior that can follow.
The short answer
Sunk cost thinking uses irrecoverable time, money, or effort as evidence for what to do next. Escalation of commitment is the continued or increased allocation of resources to a chosen course after setbacks. Sunk costs can help drive escalation, but escalation also involves responsibility, self-justification, organizational incentives, and a series of choices.
How to tell them apart
| Question | Sunk cost fallacy | Escalation of commitment |
|---|---|---|
| Core idea | Past investment is treated as a reason to continue. | Resources keep being added to a course of action after negative feedback. |
| What it names | A judgment error about costs that cannot be recovered. | A sequence of decisions and the behavior that compounds commitment. |
| Typical signal | "I cannot let what I already spent go to waste." | "One more round of resources will prove the original choice was right." |
| Important driver | The prior investment itself and the desire not to appear wasteful. | Prior investment plus responsibility, self-justification, reputation, and repeated choice. |
| Best check | Would I choose this now if the earlier investment were zero? | What new evidence would make us stop, and who can make that call without defending the original choice? |
One project, two levels
A team says, “We have already spent six months on this, so stopping would waste the work.” That is sunk cost reasoning. The team then approves another budget, misses another checkpoint, and renews the project again while the evidence worsens. That repeated allocation is escalation of commitment.
Do not confuse either pattern with perseverance
Continuing can be reasonable when current evidence supports future value. The warning sign is not persistence itself. It is using what has already been spent, or the need to vindicate an earlier choice, instead of an updated forecast.
A two-part decision test
- 1. Remove the past
If you inherited this decision today with no responsibility for it, would you invest the next dollar or hour?
- 2. Predefine the stop
Name the evidence, date, or threshold that would trigger reassessment before making the next commitment.