What is the purpose of a political party? Its basic function, in theory, is to facilitate voter choice. By representing distinct interests or worldviews, parties are supposed to offer electors a broad choice as to how they want to be governed.

Historically, parties in democratic countries did facilitate choice. They used to represent different sectional, demographic interests. In Britain, the Tories originally drew their support from the landed gentry; the Whigs from aristocrats and the wealthy middle class; Labour from unionized workers.

Parties also used to articulate different worldviews. The Tories, and later the Conservatives, stood for monarchism, protectionism, and the preservation of institutions; the Whigs, and later the Liberals, for religious nonconformity, free trade, and political reform; Labour for socialism and the expansion of the welfare state. Similarly, in ...