Perfect competition

What do we mean by perfect competition?

  • Firms are atomic

    All firms are small enough that one firm’s actions have no effect on other firms and very little effect on the total supply and total demand

  • The product is homogeneous

    All firms sell the exact same product

  • Firms and consumers have perfect information

    Both firms and consumers know the price in the market

  • Firms have equal access

    All firms have access to the same technology

  • Firms have free entry

    Firms can enter or exit the market at any time without incurring any cost

These are very strong assumptions!

These assumptions imply that all profit maximizing firms are price-takers in the market

  1. Thought experiment 1: suppose a firm sets their price above the market price
    • Equal access, atomicity, and homogeneous results in many other firms in the market who can sell the exact same product at the market price
  2. Thought experiment 2: suppose a firm sets their price below the market price
    • Then firms will be making less money than if they had priced at the market price, violating profit maximization