A single tax is a system of taxation based mainly or exclusively on one tax, typically chosen for its special properties, often being a tax on land value.
Pierre Le Pesant, sieur de Boisguilbert and Sébastien Le Prestre de Vauban were early advocates for a single tax, but, rejecting the claim that land has certain economic properties which make it uniquely suitable for taxation, they instead proposed a flat tax on all incomes.
Henry George (September 2, 1839 – October 29, 1897) was an American political economist, social philosopher and journalist. His writing was immensely popular in 19th-century America and sparked several reform movements of the Progressive Era. He inspired the economic philosophy known as Georgism, the belief that people should own the value they produce themselves, but that the economic value of land (including natural resources) should belong equally to all members of society. George famously argued that a single tax on land values would create a more productive and just society.
His most famous work, Progress and Poverty (1879), sold millions of copies worldwide. The treatise investigates the paradox of increasing inequality and poverty amid economic and technological progress, the business cycle with its cyclic nature of industrialized economies, and the use of rent capture such as land value taxation and other anti-monopoly reforms as a remedy for these and other social problems. Other works by George defended free trade, the secret ballot, free (at marginal cost) public utilities/transportation provided by the capture of their resulting land rent uplift, Pigouvian taxation, and public ownership of other natural monopolies.