Cartels face an incentive to cheat

Collective monopoly profit conflicts with individual gain.

A cartel restricts combined output to raise price and joint profit. At the cartel price, however, an individual member can often sell extra units and gain if others maintain restraint. This prisoner’s-dilemma structure makes collusion unstable.

Collectively, cartel members behave like a monopolist: choose combined output where industry MR equals MC and divide production among members. The high price creates a margin for cheating. One member can secretly expand sales at that price and capture additional profit, while the resulting price effect is shared across the cartel.

If every member cheats, total output rises and price falls, eroding the cartel gain. The contradiction is between the group optimum and each member’s unilateral incentive. An agreement alone does not remove that incentive. Monitoring and punishment must make deviation unattractive.

Cooperation becomes easier when firms are few, products and costs are similar, orders are observable, demand is stable, entry is difficult, and interaction repeats. Punishment strategies can deter cheating when firms value future profit. Antitrust law also changes expected cost by penalizing explicit agreements.

Repeated interaction changes the payoff from one-time cheating. A firm may gain today but lose future cooperative profit if rivals punish it. Cooperation is more sustainable when firms expect to remain in the market, can detect deviations quickly, and value future earnings. Anonymous, volatile demand makes cheating harder to distinguish from ordinary sales changes.

Entry weakens a cartel because outsiders can sell at the elevated price and because more members make monitoring difficult. Differing costs create conflict over production quotas: low-cost members want larger shares. Product similarity makes price comparisons easier, while differentiated terms can conceal discounts.

Game questions sometimes ask what happens after a payoff changes. Recompute best responses rather than carrying the old equilibrium forward. A subsidy to one strategy, a penalty for collusion, or a change in future profit can remove a dominant strategy or create a different Nash equilibrium. The labels “cooperate” and “defect” do not determine the answer. The displayed payoffs do.

Cheating against a fixed quota

Two firms agree to produce 40 units each at a high cartel price. If Firm A alone adds 10 units while B keeps its quota, A gains sales before price falls much. If both add 10, market output rises enough to cut price and both earn less than under restraint. Secret expansion is individually attractive yet collectively destructive.

Explicit price fixing is not required for all parallel conduct. Firms may independently respond to the same demand and cost information. Antitrust analysis distinguishes agreement from conscious but independent behavior. A economics exam item usually states communication or a cartel when collusion is intended.

Do not assume a cartel eliminates deadweight loss. Its monopoly-like restriction usually creates underproduction. Successful coordination raises joint profit but lowers total surplus relative to competitive output under standard cost assumptions.

When a question asks why cartels collapse, select the incentive to deviate or entry mechanism rather than a vague claim that firms “dislike cooperation.” The economic reason is the payoff available from expanding while others restrain output.