‘In politics, shared hatreds are almost always the basis of friendships.’ ALEXIS DE TOCQUEVILLE , Democracy in America (1835)
the way in which the political parties in a political system are grouped and structured. Possible variants that could apply to the UK include one-party dominant, two-party, two-and-a-half party and multi-party systems.
So fundamental are political parties to the operation of modern politics that their role and significance are often taken for granted. It is forgotten, for instance, that parties are a relatively recent invention. As political machines organized to win elections and wield government power, parties came into existence only in the early nineteenth century.
The best way of comparing and understanding political parties is to think of them as examples of contrasting party systems. By focusing on the number, variety, and roles of parties, the structure of a party system helps us understand how they interact with one another, and the impact of their interactions on the countries they govern
The most familiar way of distinguishing between different types of party system is by reference to the number of parties competing for power. On this basis, Duverger (1954) distinguished between ‘one-party’, ‘two-party’ and ‘multiparty’ systems. Although such a typology is commonly used, party systems cannot simply be reduced to a ‘numbers game. As important as the number of parties competing for power is their relative size, as reflected in their electoral and legislative strength. As Sartori (1976) pointed out, what is vital is to establish the ‘relevance’ of parties in relation to the formation of governments and, in particular, whether their size gives them the prospect of winning, or at least sharing, government power. This approach is often reflected in the distinction made between ‘major’, or government orientated, parties and more peripheral, ‘minor’ ones (although neither category can be defined with mathematical accuracy). A third consideration is how these ‘relevant’ parties relate to one another. Is the party system characterized by cooperation and consensus, or by conflict and polarization? This is closely linked to the ideological complexion of the party system, and the traditions and history of the parties that compose it.