When Opportunity Cost Fails

State the textbook definition of opportunity cost and the implicit assumption that it is universal. Pose the driving question: when does this frame fail?

• Opportunity cost = value of the next-best foregone alternative
• Implicit assumption: alternatives are known, comparable, and stable
• Driving question: when does reality refuse to cooperate with those assumptions?

Present three decision scenarios (job vs. grad school, stay in city vs. move abroad, scroll phone vs. sleep). Let the learner mark which scenarios they expect the textbook framework to handle correctly.

• Commit to a prediction before evidence
• Notice which scenarios feel 'easy' vs. 'messy'
• Identify the property that separates the mess

Show what real people actually do in each scenario and how that diverges from the textbook prediction. The job offer case: candidates anchor to the salary number, not to the foregone grad-school trajectory. The city case: status-quo bias dominates the move calculation. The sleep case: present bias overrides any long-horizon opportunity cost.

• Salary anchors crowd out multi-year opportunity comparisons
• Status-quo bias treats the current option as the reference, not the alternative
• Present bias makes future costs effectively zero in the moment

A simulator that lets the learner toggle three knobs — alternative clarity, comparability, and emotional stake — and watch a stylized decision-maker's choice drift away from the opportunity-cost optimum as each knob deteriorates.

• Watch the choice flip when alternatives become vague
• Watch it flip again when units stop being comparable
• Watch it flip a third time when identity is on the line

Explain the three failure conditions and what substitutes for opportunity cost inside each one. Unknown alternatives → reference-dependent reasoning. Non-commensurable alternatives → identity and narrative frames. Future-distant costs → present bias and hyperbolic discounting.

• Condition 1: alternatives are unknowable → reference-dependent anchors take over
• Condition 2: alternatives are non-commensurable → identity and narrative dominate
• Condition 3: costs are temporally distant → hyperbolic discounting collapses them
• The framework is locally valid and globally brittle

Be explicit about the boundary: opportunity cost remains accurate for small, repeated, monetary, low-identity decisions — coffee, route choice, small portfolio trades. It fails precisely as decisions become larger, rarer, and more identity-laden.

• Small repeated monetary choices: framework holds
• Large, rare, identity-laden choices: framework fails
• The transition is not gradual — there is a regime change

A single transfer question: given a new scenario (leaving a stable career to start a company), the learner must identify which failure condition is active and name the substitute heuristic at work.

• Diagnose the active failure condition
• Name the substitute heuristic
• Justify the substitution in one sentence

Resolve the driving question directly. Opportunity cost is not a universal tool; it is a tool conditioned on known, comparable, psychologically available alternatives. When those preconditions fail, decision-makers switch to reference points, identity frames, or hyperbolic discounting — and the textbook answer is wrong by construction.

• Direct answer to the driving question
• Three named preconditions, three named substitutes
• Practical rule: check the preconditions before trusting the framework