Into the seventeenth century, numerical reasoning bore no special weight in political life. Complex calculations were often regarded with suspicion, seen as the narrow province of navigators, bookkeepers, and astrologers, not gentlemen. This changed in the decades following the Glorious Revolution of 1688. Though Britons’ new quantitative enthusiasm coincided with major advances in natural science, financial capitalism, and the power of the British state, it was no automatic consequence of those developments, William Deringer argues. Rather, it was a product of politics—ugly, antagonistic, partisan politics. From parliamentary debates to cheap pamphlets, disputes over taxes, trade, and national debt were increasingly conducted through calculations. Some of the era’s most pivotal political moments, like the 1707 Union of England and Scotland and the 1720 South Sea Bubble, turned upon calculative conflicts.