Sunk-Cost Fallacy.

01Overview

The sunk-cost fallacy is accounting by emotion: money, time, and effort already gone are treated as if they could be recovered by pushing further. Rationally, only future costs and benefits should decide the next step; behaviourally, past investments become obligations, and the urge not to 'waste' what was spent drives larger wastes still. Arkes and Blumer's experiments demonstrated it in trivial settings — theatre tickets, plane fares — and the professional versions are correspondingly more expensive: escalations of commitment in firms, militaries, and governments, and careers spent defending a path chosen at twenty.

02Key theorists

Thaler named the fallacy in 1980; Staw's earlier studies of organisational commitment showed decision-makers allocating more funds to failing projects they had personally backed. Arkes and Blumer's 1985 experiments produced the canonical demonstrations: season-ticket buyers who paid full price attended more games than discount buyers, and students who paid more for a ski trip persisted through worse weather. The pattern includes the classic 'plane fare' studies in which prior expenditure changed choice even when it was plainly spent, and the metaphor of the 'Concorde fallacy' captured it in engineering politics.

03How it works

1. 01Loss aversion applied to the past: abandoning a project means realising the loss
2. 02Self-justification: continuing defends the wisdom of the original decision and its decider
3. 03Public commitment: spectators make retreat feel like humiliation
4. 04Consistency motive: people prefer to appear consistent rather than proven wrong
5. 05Agency escalation: those who initiated are the least able to walk away
6. 06'Do not waste' heuristics: thrift norms misfire when applied to irreversible spend

04Where it shows up

Holding a bad investment to 'get the money back'; finishing terrible films, books and meals; armadas of projects sustained past their useful lives; wars of attrition justified by the dead already mourned; subscriptions and memberships continued because the joining fee is gone; careers defended because of the years already given.

05The propaganda link

Escalation is how official falsehoods become permanent: a regime that has repeated a lie long enough cannot afford to retract it, so the lie is defended as policy. The past investment in the claim — and the cost of admitting it — outweighs every future benefit of truth.

06How to resist

• Run the clean-slate test: from today, would you choose this with fresh money and time?
• Appoint kill criteria before starting, and make them external and dated
• Separate the decision from the decider: audit the project, not the ego behind it
• Log the spend as tuition rather than an asset; lessons retained, money not
• Reward people for stopping visibly, so retreat stops being humiliation