Whiggism is a political philosophy that grew out of the Parliamentarian faction in the Wars of the Three Kingdoms (1639–1651). The Whigs advocated the supremacy of Parliament, tolerance of Protestant dissenters, and opposition to a "Papist" on the throne, especially James II or his descendants. It is associated with early conservative liberalism.

The Exclusion Crisis ran from 1679 until 1681 in the reign of King Charles II of England, Scotland and Ireland. Three Exclusion Bills sought to exclude the King's brother and heir presumptive, James, Duke of York, from the thrones of England, Scotland and Ireland because he was a Roman Catholic. None became law. Two new parties formed. The Tories were opposed to this exclusion, while the "Country Party", who were soon to be called the Whigs, supported it. While the matter of James's exclusion was not decided in Parliament during Charles's reign, it would come to a head only three years after James took the throne, when he was deposed in the Glorious Revolution of 1688. Finally, the Act of Settlement 1701 decided definitively that Roman Catholics were to be excluded from the English, Scottish, and Irish thrones, later the British throne.