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Argument from Sunk Cost

Also Known As: sunk cost fallacy (as argument) Concorde fallacy argument escalation of commitment
Argumentation Scheme ID: argument_from_sunk_cost

Definition

The argument from sunk cost urges continuing a course of action primarily because of the irrecoverable resources already invested in it, rather than based on the future costs and benefits of continuing versus stopping. This scheme is closely related to the argument from waste but focuses specifically on the psychological difficulty of writing off past investments. It is almost always fallacious from a rational decision-making perspective, since sunk costs should be irrelevant to forward-looking decisions.

Examples

I have already spent four years and $200,000 on this law degree. Even though I have realized I hate the legal profession, I should finish the degree and practice law for at least a few years. Otherwise, all that time and money will have been for nothing.

Our team has been developing this software feature for eight months and spent 600 developer-hours on it. Even though user research now shows customers don't want it, we should ship it anyway so all that work isn't wasted.

I've been in this relationship for six years, so even though we've grown apart and are both unhappy, it makes no sense to break up now. Leaving would mean all that time together meant nothing.

Verification Steps
Verification Steps
Binary yes/no questions that an AI must answer to detect a reasoning pattern in a text.
Each of the 452 aspects has verification steps — simple yes/no questions designed to systematically detect whether a pattern appears in a text. For ad hominem: "Does the argument attack a person rather than their claim?" For false dichotomy: "Are only two options presented when more exist?" This ensures consistent, reproducible analysis.

Binary (yes/no) questions an LLM must answer to identify this aspect:

  1. 1

    Is past investment being cited as a reason to continue a course of action?

    Type: binary
  2. 2

    Would the decision be the same if no prior investment had been made?

    Type: binary
  3. 3

    Are future costs and benefits being properly evaluated independent of sunk costs?

    Type: binary
  4. 4

    Is emotional attachment to the investment influencing the reasoning?

    Type: binary
Deep Dive
The expandable detail section on each aspect page with examples, psychology, and counter-strategies.
The Deep Dive section provides in-depth information about each aspect: a real-world example showing the pattern in action, an explanation of why it works psychologically, practical advice on how to counter it, alternative names, and links to related aspects.