Abstract
Adaptations to coordination problems endogenous to political parties have established the cartel party as the emerging equilibrium type in modern Western democracies. However, these factors alone are insufficient to maintain such an equilibrium given the threat of defection. That threat is mitigated by three factors: historical changes in party form, systemic changes in the global economy and changed ideas about governments. Together, these changes produce both a cartel of parties and the cartel party organisational form, without requiring overt conspiracy. These speculations are mapped onto actual experiences of the UK, the US and Sweden. The theory of the cartel party is advanced by emphasis on the 'cost of production' of policies and the constriction of the policy-space over which parties compete. We also explain why a cartel of parties might be stable, notwithstanding the temptation to defection often attributed to cartels as multi-player prisoners' dilemmas.