# Sunk cost fallacy

*Also called: Concorde fallacy, escalation of commitment*

- **Cluster:** Values and premises — Hidden value claims doing the arguing
- **Page:** https://fallacy.wiki/fallacy/sunk-cost/
- **In Arabic:** https://fallacy.wiki/ar/fallacy/sunk-cost.md
- **Licence:** CC BY 4.0 — https://creativecommons.org/licenses/by/4.0/

## What it is

Letting money or effort already spent justify continuing, when only future returns matter.

## In the wild

> We have spent two years on it, so we must finish.

## How to answer it

Ask what you would decide if you were starting from today with nothing spent.

## Origin and naming

Hal Arkes and Catherine Blumer documented the effect in 1985 ('The Psychology of Sunk Cost') as the tendency to keep investing once money, effort, or time has been spent. It is also called the Concorde fallacy, after the British and French governments that kept funding the supersonic jet long after its commercial case had collapsed.

## More places it shows up

- The startup has burned eighteen months and two funding rounds on a feature nobody uses, and the board approves a third because 'we're too far in to stop now'.
- A reader finishes the thousand-page fantasy series they stopped enjoying at book two, because abandoning it now would waste the first eight hundred pages.
- In the meeting about the failing contractor, the project lead argues to keep them through phase three — 'we've already trained them on our systems'.
- He holds the losing stock from $40 down to $4, telling his broker he 'can't sell at a loss' — as if the $36 were still on the table to be recovered.

## How to spot it

- The justification is all in the past tense: money spent, years invested, effort poured — nothing about what comes next.
- Ask 'if you were starting from today, would you choose this?' and the answer changes the subject to what's already gone.
- The counterargument is always offered as proof of commitment, not as evidence the commitment is working.

## Nearby

- [Wishful thinking](https://fallacy.wiki/fallacy/wishful-thinking.md)
- [Slothful induction](https://fallacy.wiki/fallacy/slothful-induction.md)
- [Appeal to consequences](https://fallacy.wiki/fallacy/consequences.md)

## Read more

- [Wikipedia](https://en.wikipedia.org/wiki/Sunk_cost)
- [The Decision Lab](https://thedecisionlab.com/biases/the-sunk-cost-fallacy)

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From fallacy.wiki — a bilingual field guide to 91 logical fallacies, published by phi holdings. Licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/): reuse freely with attribution to fallacy.wiki.