Sunk Cost Fallacy

Definition

Let:

• $P$ : A course of action or investment
• $R$ : Resources already invested in $P$ (time, money, effort)

Then an argument commits the Sunk Cost Fallacy if and only if it asserts:

$$\text{We’ve invested }R\text{ in }P⟹\text{We must continue with }P$$

NOTE

Sunk costs cannot be recovered and should not influence future decisions.