Externalities, Public Goods
The Vaccination Mandate
The Vaccination Mandate is an Externalities and Public Goods scenario. The core lesson: Vaccination is a classic externality problem where private benefit and public benefit diverge. You're the state health officer. A new vaccine for a highly infectious disease is available. DecisionPlay maps the players, payoffs, and equilibrium dynamics that shape how this situation typically resolves.
The situation
You're the state health officer. A new vaccine for a highly infectious disease is available. The disease kills 1 in 1000 unvaccinated people. The vaccine is 95% effective with minor side effects. Without widespread vaccination, the disease will spread widely.
Background
Vaccination creates a positive externality: getting vaccinated protects not just you but others who can't be vaccinated. This creates a free-rider incentive: individuals can benefit from herd immunity without taking on the vaccine's small risk. When enough people free-ride, herd immunity collapses and everyone is worse off.
What this reveals
The boundary between individual rights and collective welfare
Vaccination is among the clearest real-world examples of the externality problem: your decision has direct consequences for people who have no say in it. The people who most need herd immunity are those who can't be vaccinated, immunocompromised individuals, infants, transplant recipients. A pure individual-liberty framing ignores these third parties entirely. The policy question isn't 'should individuals have rights?', it's 'where do individual rights end when they impose costs on non-consenting third parties?'
How to counter it: When evaluating any individual-freedom argument, ask: who bears the cost if everyone makes this choice? If the cost falls primarily on people who didn't make the choice, the freedom claim is weaker than it looks.
A question to sit with
Where in your life are you relying on others to take action that protects you, without being required to take that action yourself?
Frequently asked questions
- What game theory concept does The Vaccination Mandate illustrate?
- The Vaccination Mandate illustrates Externalities, Public Goods. Vaccination is a classic externality problem where private benefit and public benefit diverge.
- What is the situation in The Vaccination Mandate?
- You're the state health officer. A new vaccine for a highly infectious disease is available. The disease kills 1 in 1000 unvaccinated people.
- What does The Vaccination Mandate reveal about how people decide?
- The boundary between individual rights and collective welfare. Vaccination is among the clearest real-world examples of the externality problem: your decision has direct consequences for people who have no say in it. The people who most need herd immunity are those who can't be vaccinated, immunocompromised individuals, infants, transplant recipients. A pure individual-liberty framing ignores these third parties entirely. The policy question isn't 'should individuals have rights?', it's 'where do individual rights end when they impose costs on non-consenting third parties?'
- How do you avoid the trap in The Vaccination Mandate?
- When evaluating any individual-freedom argument, ask: who bears the cost if everyone makes this choice? If the cost falls primarily on people who didn't make the choice, the freedom claim is weaker than it looks.
- What is the research behind The Vaccination Mandate?
- Vaccination creates a positive externality: getting vaccinated protects not just you but others who can't be vaccinated. This creates a free-rider incentive: individuals can benefit from herd immunity without taking on the vaccine's small risk. When enough people free-ride, herd immunity collapses and everyone is worse off.
- How long does The Vaccination Mandate take to play?
- About 10 min, at core difficulty, across 4 decision points. It runs in your browser with no account and no sign-in.
Keep exploring
More Civic & Policy scenarios, or browse all scenarios. New to this? Start with how DecisionPlay works or the game theory glossary.
Topics: vaccination, public-goods, externalities, policy