Lecture Notes: The Tragedy of the Commons

Introduction: Thought Experiment

• Scenario: Living in a village depending on a local fish pond for food
• Shared by four villagers
• Pond starts with 12 fish; fish reproduce at a rate of one new fish per pair per night
• Goal: Maximize food supply by deciding how many fish to catch daily
• Solution: Each villager should catch one fish per day

Explanation of Solution

• If each villager catches one fish:
  • 8 fish left overnight
  • 4 pairs produce 4 babies, replenishing to 12 fish
• Catching more than one fish reduces reproductive pairs, leading to depletion
• Outcome: Overfishing leads to starvation

Concept: Tragedy of the Commons

• Origin:
  • Described by economist William Forster Lloyd (1833) regarding cattle overgrazing
  • Revived by ecologist Garrett Hardin to describe shared limited resources
• Situations involve:
  • Short-term self-interest vs. common good
  • Results: Overgrazing, overfishing, pollution, etc.

Key Features

• Opportunity for individual benefit while spreading negative effects
• Example: Fish pond scenario
  • Individual fishermen motivated to catch more fish
  • Decline in fish reproduction is a shared consequence
• Problem: Optimizing for self in short-term harms everyone in the long-term

Real-Life Examples

• Overuse of antibiotics
  • Short-term gains in livestock and illness treatment
  • Evolution of antibiotic-resistant bacteria
• Coal-fired power plants
  • Cheap electricity and profits
  • Long-term pollution effects
• Other examples: Littering, water shortages, deforestation, traffic jams, bottled water

Human Solutions

• Social contracts, communal agreements, electing governments, passing laws
• Aim to save collective selves from individual impulses
• Humans have the capability to solve these problems by remembering the lesson of the commons

Conclusion

• What’s good for all is good for each
• Encouragement to support TED-Ed on Patreon